feat: add post and single page statistics (#2476)

#### What type of PR is this?
/kind feature
/area core
/milestone 2.0
/kind api-change

#### What this PR does / why we need it:
新增文章和自定义页面统计功能：
1. 浏览量统计，通过在指定模板页面插入 tracker js 上报浏览量数据并写日志到文件同时通过 Metrics 暴露数据
2. 浏览量日志异步写文件
3. 文章列表和自定义页面列表数据增加 stats 属性
4. 主题文章列表及详情、自定义页面详情增加 stats 属性
5. 新增仪表盘统计数据展示, endpoint: `/apis/api.console.halo.run/v1alpha1/stats`
```java
private Integer visits;
private Integer comments;
private Integer approvedComments;
private Integer upvotes;
private Integer users;
```

#### Which issue(s) this PR fixes:

Fixes #2430

#### Special notes for your reviewer:
how to test it?
1. 使用一个主题，创建几篇文章和一些自定义页面，访问他们，并在详情页面的 head 总看到一个 `halo-tracker.js` 的 script 标签
![telegram-cloud-document-5-6167924618783885123](https://user-images.githubusercontent.com/38999863/192552428-b5635607-9810-4be3-b1fe-8a54ed3407c5.jpg)
2. 访问10次以上可以看到 halo work下有一个 `logs/visits.log`,里面有访问记录，它是10条为一批异步刷新到磁盘
3. 主题端文章列表及详情和自定义页面的详情可以取到一个stats字段
4.  `/apis/api.console.halo.run/v1alpha1/stats` 此 endpoint 可以得到总的访问量和评论量，这些数据也是异步的会有一分钟延迟

/cc @halo-dev/sig-halo 
#### Does this PR introduce a user-facing change?

```release-note
None
```

src/main/java/run/halo/app/Application.java

@@ -4,6 +4,7 @@ import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.scheduling.annotation.EnableScheduling;
 import run.halo.app.infra.properties.HaloProperties;
 import run.halo.app.infra.properties.JwtProperties;
 
@@ -15,6 +16,7 @@ import run.halo.app.infra.properties.JwtProperties;
  * @author guqing
  * @date 2017-11-14
  */
+@EnableScheduling
 @SpringBootApplication(scanBasePackages = "run.halo.app", exclude =
     IntegrationAutoConfiguration.class)
 @EnableConfigurationProperties({HaloProperties.class, JwtProperties.class})

src/main/java/run/halo/app/config/ExtensionConfiguration.java

@@ -1,5 +1,6 @@
 package run.halo.app.config;
 
+import io.micrometer.core.instrument.MeterRegistry;
 import org.pf4j.PluginManager;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.context.ApplicationContext;
@@ -202,9 +203,10 @@ public class ExtensionConfiguration {
         }
 
         @Bean
-        Controller commentController(ExtensionClient client) {
+        Controller commentController(ExtensionClient client, MeterRegistry meterRegistry,
+            SchemeManager schemeManager) {
             return new ControllerBuilder("comment-controller", client)
-                .reconciler(new CommentReconciler(client))
+                .reconciler(new CommentReconciler(client, meterRegistry, schemeManager))
                 .extension(new Comment())
                 .build();
         }

src/main/java/run/halo/app/content/ListedPost.java

@@ -28,4 +28,7 @@ public class ListedPost {
 
     @Schema(required = true)
     private List<Contributor> contributors;
+
+    @Schema(required = true)
+    private Stats stats;
 }

src/main/java/run/halo/app/content/ListedSinglePage.java

@@ -20,4 +20,7 @@ public class ListedSinglePage {
 
     @Schema(required = true)
     private List<Contributor> contributors;
+
+    @Schema(required = true)
+    private Stats stats;
 }

src/main/java/run/halo/app/content/Stats.java

@@ -0,0 +1,23 @@
+package run.halo.app.content;
+
+import lombok.Builder;
+import lombok.Value;
+
+/**
+ * Stats value object.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@Value
+@Builder
+public class Stats {
+
+    Integer visit;
+
+    Integer upvote;
+
+    Integer totalComment;
+
+    Integer approvedComment;
+}

src/main/java/run/halo/app/content/impl/PostServiceImpl.java

@@ -24,7 +24,9 @@ import run.halo.app.content.PostQuery;
 import run.halo.app.content.PostRequest;
 import run.halo.app.content.PostService;
 import run.halo.app.content.PostSorter;
+import run.halo.app.content.Stats;
 import run.halo.app.core.extension.Category;
+import run.halo.app.core.extension.Counter;
 import run.halo.app.core.extension.Post;
 import run.halo.app.core.extension.Snapshot;
 import run.halo.app.core.extension.Tag;
@@ -33,6 +35,8 @@ import run.halo.app.extension.ListResult;
 import run.halo.app.extension.ReactiveExtensionClient;
 import run.halo.app.infra.Condition;
 import run.halo.app.infra.ConditionStatus;
+import run.halo.app.metrics.CounterService;
+import run.halo.app.metrics.MeterUtils;
 
 /**
  * A default implementation of {@link PostService}.
@@ -44,10 +48,13 @@ import run.halo.app.infra.ConditionStatus;
 public class PostServiceImpl implements PostService {
     private final ContentService contentService;
     private final ReactiveExtensionClient client;
+    private final CounterService counterService;
 
-    public PostServiceImpl(ContentService contentService, ReactiveExtensionClient client) {
+    public PostServiceImpl(ContentService contentService, ReactiveExtensionClient client,
+        CounterService counterService) {
         this.contentService = contentService;
         this.client = client;
+        this.counterService = counterService;
     }
 
     @Override
@@ -67,6 +74,19 @@ public class PostServiceImpl implements PostService {
             );
     }
 
+    Stats fetchStats(Post post) {
+        Assert.notNull(post, "The post must not be null.");
+        String name = post.getMetadata().getName();
+        Counter counter =
+            counterService.getByName(MeterUtils.nameOf(Post.class, name));
+        return Stats.builder()
+            .visit(counter.getVisit())
+            .upvote(counter.getUpvote())
+            .totalComment(counter.getApprovedComment())
+            .approvedComment(counter.getApprovedComment())
+            .build();
+    }
+
     Predicate<Post> postListPredicate(PostQuery query) {
         Predicate<Post> paramPredicate = post ->
             contains(query.getCategories(), post.getSpec().getCategories())
@@ -132,6 +152,7 @@ public class PostServiceImpl implements PostService {
             .map(p -> {
                 ListedPost listedPost = new ListedPost();
                 listedPost.setPost(p);
+                listedPost.setStats(fetchStats(post));
                 return listedPost;
             })
             .flatMap(lp -> setTags(post.getSpec().getTags(), lp))

src/main/java/run/halo/app/content/impl/SinglePageServiceImpl.java

@@ -24,6 +24,8 @@ import run.halo.app.content.SinglePageQuery;
 import run.halo.app.content.SinglePageRequest;
 import run.halo.app.content.SinglePageService;
 import run.halo.app.content.SinglePageSorter;
+import run.halo.app.content.Stats;
+import run.halo.app.core.extension.Counter;
 import run.halo.app.core.extension.Post;
 import run.halo.app.core.extension.SinglePage;
 import run.halo.app.core.extension.Snapshot;
@@ -32,6 +34,8 @@ import run.halo.app.extension.ListResult;
 import run.halo.app.extension.ReactiveExtensionClient;
 import run.halo.app.infra.Condition;
 import run.halo.app.infra.ConditionStatus;
+import run.halo.app.metrics.CounterService;
+import run.halo.app.metrics.MeterUtils;
 
 /**
  * Single page service implementation.
@@ -45,9 +49,13 @@ public class SinglePageServiceImpl implements SinglePageService {
 
     private final ReactiveExtensionClient client;
 
-    public SinglePageServiceImpl(ContentService contentService, ReactiveExtensionClient client) {
+    private final CounterService counterService;
+
+    public SinglePageServiceImpl(ContentService contentService, ReactiveExtensionClient client,
+        CounterService counterService) {
         this.contentService = contentService;
         this.client = client;
+        this.counterService = counterService;
     }
 
     @Override
@@ -179,6 +187,7 @@ public class SinglePageServiceImpl implements SinglePageService {
             .map(sp -> {
                 ListedSinglePage listedSinglePage = new ListedSinglePage();
                 listedSinglePage.setPage(singlePage);
+                listedSinglePage.setStats(fetchStats(singlePage));
                 return listedSinglePage;
             })
             .flatMap(lsp ->
@@ -194,6 +203,19 @@ public class SinglePageServiceImpl implements SinglePageService {
             .defaultIfEmpty(singlePage);
     }
 
+    Stats fetchStats(SinglePage singlePage) {
+        Assert.notNull(singlePage, "The singlePage must not be null.");
+        String name = singlePage.getMetadata().getName();
+        Counter counter =
+            counterService.getByName(MeterUtils.nameOf(SinglePage.class, name));
+        return Stats.builder()
+            .visit(counter.getVisit())
+            .upvote(counter.getUpvote())
+            .totalComment(counter.getApprovedComment())
+            .approvedComment(counter.getApprovedComment())
+            .build();
+    }
+
     private Flux<Contributor> listContributors(List<String> usernames) {
         if (usernames == null) {
             return Flux.empty();

src/main/java/run/halo/app/core/extension/Counter.java

@@ -0,0 +1,59 @@
+package run.halo.app.core.extension;
+
+import io.micrometer.core.instrument.Meter;
+import java.util.Collection;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+import run.halo.app.extension.AbstractExtension;
+import run.halo.app.extension.GVK;
+import run.halo.app.metrics.MeterUtils;
+
+/**
+ * A counter for number of requests by extension resource name.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@Data
+@GVK(group = "metrics.halo.run", version = "v1alpha1", kind = "Counter", plural = "counters",
+    singular = "counter")
+@EqualsAndHashCode(callSuper = true)
+public class Counter extends AbstractExtension {
+
+    private Integer visit;
+
+    private Integer upvote;
+
+    private Integer totalComment;
+
+    private Integer approvedComment;
+
+    /**
+     * Populate counter data from {@link Meter}s.
+     *
+     * @param meters counter meters
+     */
+    public <T extends Meter> void populateFrom(Collection<T> meters) {
+        populateDefaultValue();
+        for (Meter meter : meters) {
+            if (meter instanceof io.micrometer.core.instrument.Counter meterCounter) {
+                if (MeterUtils.isVisitCounter(meterCounter)) {
+                    this.visit = (int) meterCounter.count();
+                } else if (MeterUtils.isUpvoteCounter(meterCounter)) {
+                    this.upvote = (int) meterCounter.count();
+                } else if (MeterUtils.isTotalCommentCounter(meterCounter)) {
+                    this.totalComment = (int) meterCounter.count();
+                } else if (MeterUtils.isApprovedCommentCounter(meterCounter)) {
+                    this.approvedComment = (int) meterCounter.count();
+                }
+            }
+        }
+    }
+
+    private void populateDefaultValue() {
+        this.visit = 0;
+        this.upvote = 0;
+        this.totalComment = 0;
+        this.approvedComment = 0;
+    }
+}

src/main/java/run/halo/app/core/extension/endpoint/CommentEndpoint.java

@@ -6,10 +6,8 @@ import static org.springdoc.core.fn.builders.parameter.Builder.parameterBuilder;
 import static org.springdoc.core.fn.builders.requestbody.Builder.requestBodyBuilder;
 
 import io.swagger.v3.oas.annotations.enums.ParameterIn;
-import org.apache.commons.lang3.StringUtils;
 import org.springdoc.core.fn.builders.schema.Builder;
 import org.springdoc.webflux.core.fn.SpringdocRouteBuilder;
-import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
 import org.springframework.stereotype.Component;
 import org.springframework.web.reactive.function.server.RouterFunction;
@@ -26,6 +24,7 @@ import run.halo.app.core.extension.Comment;
 import run.halo.app.core.extension.Reply;
 import run.halo.app.extension.ListResult;
 import run.halo.app.extension.router.QueryParamBuildUtil;
+import run.halo.app.infra.utils.HaloUtils;
 import run.halo.app.infra.utils.IpAddressUtils;
 
 
@@ -106,7 +105,7 @@ public class CommentEndpoint implements CustomEndpoint {
             .flatMap(commentRequest -> {
                 Comment comment = commentRequest.toComment();
                 comment.getSpec().setIpAddress(IpAddressUtils.getIpAddress(request));
-                comment.getSpec().setUserAgent(userAgentFrom(request));
+                comment.getSpec().setUserAgent(HaloUtils.userAgentFrom(request));
                 return commentService.create(comment);
             })
             .flatMap(comment -> ServerResponse.ok().bodyValue(comment));
@@ -118,26 +117,10 @@ public class CommentEndpoint implements CustomEndpoint {
             .flatMap(replyRequest -> {
                 Reply reply = replyRequest.toReply();
                 reply.getSpec().setIpAddress(IpAddressUtils.getIpAddress(request));
-                reply.getSpec().setUserAgent(userAgentFrom(request));
+                reply.getSpec().setUserAgent(HaloUtils.userAgentFrom(request));
                 return replyService.create(commentName, reply);
             })
             .flatMap(comment -> ServerResponse.ok().bodyValue(comment));
     }
 
-    /**
-     * Gets user-agent from server request.
-     *
-     * @param request server request
-     * @return user-agent string if found, otherwise "unknown"
-     */
-    public static String userAgentFrom(ServerRequest request) {
-        HttpHeaders httpHeaders = request.headers().asHttpHeaders();
-        // https://en.wikipedia.org/wiki/User_agent
-        String userAgent = httpHeaders.getFirst(HttpHeaders.USER_AGENT);
-        if (StringUtils.isBlank(userAgent)) {
-            // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-CH-UA
-            userAgent = httpHeaders.getFirst("Sec-CH-UA");
-        }
-        return StringUtils.defaultString(userAgent, "unknown");
-    }
 }

src/main/java/run/halo/app/core/extension/endpoint/StatsEndpoint.java

@@ -0,0 +1,99 @@
+package run.halo.app.core.extension.endpoint;
+
+import static org.springdoc.core.fn.builders.apiresponse.Builder.responseBuilder;
+
+import lombok.Data;
+import org.springdoc.webflux.core.fn.SpringdocRouteBuilder;
+import org.springframework.stereotype.Component;
+import org.springframework.web.reactive.function.server.RouterFunction;
+import org.springframework.web.reactive.function.server.ServerRequest;
+import org.springframework.web.reactive.function.server.ServerResponse;
+import reactor.core.publisher.Mono;
+import run.halo.app.core.extension.Counter;
+import run.halo.app.core.extension.Post;
+import run.halo.app.core.extension.User;
+import run.halo.app.extension.ReactiveExtensionClient;
+
+/**
+ * Stats endpoint.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@Component
+public class StatsEndpoint implements CustomEndpoint {
+
+    private final ReactiveExtensionClient client;
+
+    public StatsEndpoint(ReactiveExtensionClient client) {
+        this.client = client;
+    }
+
+    @Override
+    public RouterFunction<ServerResponse> endpoint() {
+        final var tag = "api.console.halo.run/v1alpha1/Stats";
+        return SpringdocRouteBuilder.route()
+            .GET("stats", this::getStats, builder -> builder.operationId("getStats")
+                .description("Get stats.")
+                .tag(tag)
+                .response(responseBuilder()
+                    .implementation(Stats.class)
+                )
+            )
+            .build();
+    }
+
+    Mono<ServerResponse> getStats(ServerRequest request) {
+        return client.list(Counter.class, null, null)
+            .reduce(Stats.emptyStats(), (stats, counter) -> {
+                stats.setVisits(stats.getVisits() + counter.getVisit());
+                stats.setComments(stats.getComments() + counter.getTotalComment());
+                stats.setApprovedComments(
+                    stats.getApprovedComments() + counter.getApprovedComment());
+                stats.setUpvotes(stats.getUpvotes() + counter.getUpvote());
+                return stats;
+            })
+            .flatMap(stats -> client.list(User.class,
+                    user -> user.getMetadata().getDeletionTimestamp() == null,
+                    null)
+                .count()
+                .map(count -> {
+                    stats.setUsers(count.intValue());
+                    return stats;
+                }))
+            .flatMap(stats -> client.list(Post.class, post -> !post.isDeleted(), null)
+                .count()
+                .map(count -> {
+                    stats.setPosts(count.intValue());
+                    return stats;
+                })
+            )
+            .flatMap(stats -> ServerResponse.ok().bodyValue(stats));
+    }
+
+    @Data
+    public static class Stats {
+        private Integer visits;
+        private Integer comments;
+        private Integer approvedComments;
+        private Integer upvotes;
+        private Integer users;
+        private Integer posts;
+
+        /**
+         * Creates an empty stats that populated initialize value.
+         *
+         * @return stats with initialize value.
+         */
+        public static Stats emptyStats() {
+            Stats stats = new Stats();
+            stats.setVisits(0);
+            stats.setComments(0);
+            stats.setApprovedComments(0);
+            stats.setUpvotes(0);
+            stats.setUsers(0);
+            stats.setPosts(0);
+            return stats;
+        }
+    }
+}

src/main/java/run/halo/app/core/extension/endpoint/TrackerEndpoint.java

@@ -0,0 +1,119 @@
+package run.halo.app.core.extension.endpoint;
+
+import static org.springdoc.core.fn.builders.apiresponse.Builder.responseBuilder;
+import static org.springdoc.core.fn.builders.content.Builder.contentBuilder;
+import static org.springdoc.core.fn.builders.requestbody.Builder.requestBodyBuilder;
+
+import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.MeterRegistry;
+import org.apache.commons.lang3.StringUtils;
+import org.springdoc.core.fn.builders.schema.Builder;
+import org.springdoc.webflux.core.fn.SpringdocRouteBuilder;
+import org.springframework.http.MediaType;
+import org.springframework.stereotype.Component;
+import org.springframework.util.Assert;
+import org.springframework.web.reactive.function.server.RouterFunction;
+import org.springframework.web.reactive.function.server.ServerRequest;
+import org.springframework.web.reactive.function.server.ServerResponse;
+import reactor.core.publisher.Mono;
+import run.halo.app.extension.GroupVersion;
+import run.halo.app.infra.utils.HaloUtils;
+import run.halo.app.infra.utils.IpAddressUtils;
+import run.halo.app.metrics.MeterUtils;
+import run.halo.app.metrics.VisitLogWriter;
+
+/**
+ * Metrics counter endpoint.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@Component
+public class TrackerEndpoint implements CustomEndpoint {
+
+    private final MeterRegistry meterRegistry;
+    private final VisitLogWriter visitLogWriter;
+
+    public TrackerEndpoint(MeterRegistry meterRegistry, VisitLogWriter visitLogWriter) {
+        this.meterRegistry = meterRegistry;
+        this.visitLogWriter = visitLogWriter;
+    }
+
+    @Override
+    public RouterFunction<ServerResponse> endpoint() {
+        final var tag = "api.halo.run/v1alpha1/Tracker";
+        return SpringdocRouteBuilder.route()
+            .POST("trackers/counter", this::increase,
+                builder -> builder.operationId("count")
+                    .description("Count an extension resource visits.")
+                    .tag(tag)
+                    .requestBody(requestBodyBuilder()
+                        .required(true)
+                        .content(contentBuilder()
+                            .mediaType(MediaType.APPLICATION_JSON_VALUE)
+                            .schema(Builder.schemaBuilder()
+                                .implementation(CounterRequest.class))
+                        ))
+                    .response(responseBuilder()
+                        .implementation(Double.class))
+            )
+            .build();
+    }
+
+    private Mono<ServerResponse> increase(ServerRequest request) {
+        return request.bodyToMono(CounterRequest.class)
+            .switchIfEmpty(
+                Mono.error(new IllegalArgumentException("Counter request body must not be empty")))
+            .map(counterRequest -> {
+                String counterName =
+                    MeterUtils.nameOf(counterRequest.group(), counterRequest.plural(),
+                        counterRequest.name());
+
+                Counter counter = MeterUtils.visitCounter(meterRegistry, counterName);
+                counter.increment();
+                // async write visit log
+                writeVisitLog(request, counterRequest);
+                return (int) counter.count();
+            })
+            .flatMap(count -> ServerResponse.ok().bodyValue(count));
+    }
+
+    public record CounterRequest(String group, String plural, String name, String hostname,
+                                 String screen, String language, String referrer) {
+        /**
+         * Construct counter request.
+         * group and session uid can be empty.
+         */
+        public CounterRequest {
+            Assert.notNull(plural, "The plural must not be null.");
+            Assert.notNull(name, "The name must not be null.");
+            group = StringUtils.defaultString(group);
+        }
+    }
+
+    private void writeVisitLog(ServerRequest request, CounterRequest counterRequest) {
+        String logMessage = logMessage(request, counterRequest);
+        visitLogWriter.log(logMessage);
+    }
+
+    private String logMessage(ServerRequest request, CounterRequest counterRequest) {
+        String ipAddress = IpAddressUtils.getIpAddress(request);
+        String hostname = counterRequest.hostname();
+        String screen = counterRequest.screen();
+        String language = counterRequest.language();
+        String referrer = counterRequest.referrer();
+        String userAgent = HaloUtils.userAgentFrom(request);
+        String counterName =
+            MeterUtils.nameOf(counterRequest.group(), counterRequest.plural(),
+                counterRequest.name());
+        return String.format(
+            "subject=[%s], ipAddress=[%s], hostname=[%s], screen=[%s], language=[%s], "
+                + "referrer=[%s], userAgent=[%s]", counterName, ipAddress, hostname, screen,
+            language, referrer, userAgent);
+    }
+
+    @Override
+    public GroupVersion groupVersion() {
+        return new GroupVersion("api.halo.run", "v1alpha1");
+    }
+}

src/main/java/run/halo/app/core/extension/reconciler/CommentReconciler.java

@@ -1,17 +1,27 @@
 package run.halo.app.core.extension.reconciler;
 
+import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.MeterRegistry;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.Comparator;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import java.util.function.Function;
+import java.util.stream.Collectors;
+import org.springframework.lang.Nullable;
 import run.halo.app.core.extension.Comment;
 import run.halo.app.core.extension.Reply;
 import run.halo.app.extension.ExtensionClient;
+import run.halo.app.extension.GroupVersionKind;
+import run.halo.app.extension.Ref;
+import run.halo.app.extension.SchemeManager;
 import run.halo.app.extension.controller.Reconciler;
 import run.halo.app.infra.utils.JsonUtils;
+import run.halo.app.metrics.MeterUtils;
 
 /**
  * Reconciler for {@link Comment}.
@@ -22,9 +32,14 @@ import run.halo.app.infra.utils.JsonUtils;
 public class CommentReconciler implements Reconciler<Reconciler.Request> {
     public static final String FINALIZER_NAME = "comment-protection";
     private final ExtensionClient client;
+    private final MeterRegistry meterRegistry;
+    private final SchemeManager schemeManager;
 
-    public CommentReconciler(ExtensionClient client) {
+    public CommentReconciler(ExtensionClient client, MeterRegistry meterRegistry,
+        SchemeManager schemeManager) {
         this.client = client;
+        this.meterRegistry = meterRegistry;
+        this.schemeManager = schemeManager;
     }
 
     @Override
@@ -37,6 +52,7 @@ public class CommentReconciler implements Reconciler<Reconciler.Request> {
                 }
                 addFinalizerIfNecessary(comment);
                 reconcileStatus(request.name());
+                reconcileCommentCount();
                 return new Result(true, Duration.ofMinutes(1));
             })
             .orElseGet(() -> new Result(false, null));
@@ -95,6 +111,67 @@ public class CommentReconciler implements Reconciler<Reconciler.Request> {
             });
     }
 
+    private void reconcileCommentCount() {
+        Map<Ref, List<RefCommentTuple>> map = client.list(Comment.class, null, null)
+            .stream()
+            .map(comment -> {
+                boolean approved =
+                    Objects.equals(true, comment.getSpec().getApproved())
+                        && !isDeleted(comment);
+                return new RefCommentTuple(comment.getSpec().getSubjectRef(),
+                    comment.getMetadata().getName(), approved);
+            })
+            .collect(Collectors.groupingBy(RefCommentTuple::ref));
+        map.forEach((ref, pairs) -> {
+            GroupVersionKind groupVersionKind = groupVersionKind(ref);
+            if (groupVersionKind == null) {
+                return;
+            }
+            // approved total count
+            long approvedTotalCount = pairs.stream()
+                .filter(refCommentPair -> refCommentPair.approved)
+                .count();
+            // total count
+            int totalCount = pairs.size();
+
+            schemeManager.fetch(groupVersionKind).ifPresent(scheme -> {
+                String counterName = MeterUtils.nameOf(ref.getGroup(), scheme.plural(),
+                    ref.getName());
+                // meter for total comment count
+                calcTotalComments(totalCount, counterName);
+                // meter for approved comment count
+                calcApprovedComments(approvedTotalCount, counterName);
+            });
+        });
+    }
+
+    private void calcTotalComments(int totalCount, String counterName) {
+        Counter totalCommentCounter =
+            MeterUtils.totalCommentCounter(meterRegistry, counterName);
+        double totalCountMeter = totalCommentCounter.count();
+        double totalIncrement = totalCount - totalCountMeter;
+        if (totalCountMeter + totalIncrement >= 0) {
+            totalCommentCounter.increment(totalIncrement);
+        } else {
+            totalCommentCounter.increment(totalCountMeter * -1);
+        }
+    }
+
+    private void calcApprovedComments(long approvedTotalCount, String counterName) {
+        Counter approvedCommentCounter =
+            MeterUtils.approvedCommentCounter(meterRegistry, counterName);
+        double approvedComments = approvedCommentCounter.count();
+        double increment = approvedTotalCount - approvedCommentCounter.count();
+        if (approvedComments + increment >= 0) {
+            approvedCommentCounter.increment(increment);
+        } else {
+            approvedCommentCounter.increment(approvedComments * -1);
+        }
+    }
+
+    record RefCommentTuple(Ref ref, String name, boolean approved) {
+    }
+
     private void cleanUpResourcesAndRemoveFinalizer(String commentName) {
         client.fetch(Comment.class, commentName).ifPresent(comment -> {
             cleanUpResources(comment);
@@ -111,6 +188,27 @@ public class CommentReconciler implements Reconciler<Reconciler.Request> {
                     .equals(reply.getSpec().getCommentName()),
                 null)
             .forEach(client::delete);
+        // decrement total comment count
+        Ref subjectRef = comment.getSpec().getSubjectRef();
+        GroupVersionKind groupVersionKind = groupVersionKind(subjectRef);
+        if (groupVersionKind == null) {
+            return;
+        }
+        schemeManager.fetch(groupVersionKind)
+            .ifPresent(scheme -> {
+                String counterName = MeterUtils.nameOf(subjectRef.getGroup(), scheme.plural(),
+                    subjectRef.getName());
+                MeterUtils.totalCommentCounter(meterRegistry, counterName)
+                    .increment(-1);
+            });
+    }
+
+    @Nullable
+    private GroupVersionKind groupVersionKind(Ref ref) {
+        if (ref == null) {
+            return null;
+        }
+        return new GroupVersionKind(ref.getGroup(), ref.getVersion(), ref.getKind());
     }
 
     Comparator<Reply> defaultReplyComparator() {

src/main/java/run/halo/app/infra/SchemeInitializer.java

@@ -6,6 +6,7 @@ import org.springframework.lang.NonNull;
 import org.springframework.stereotype.Component;
 import run.halo.app.core.extension.Category;
 import run.halo.app.core.extension.Comment;
+import run.halo.app.core.extension.Counter;
 import run.halo.app.core.extension.Menu;
 import run.halo.app.core.extension.MenuItem;
 import run.halo.app.core.extension.Plugin;
@@ -62,5 +63,7 @@ public class SchemeInitializer implements ApplicationListener<ApplicationStarted
         schemeManager.register(Policy.class);
         schemeManager.register(Attachment.class);
         schemeManager.register(PolicyTemplate.class);
+        // metrics.halo.run
+        schemeManager.register(Counter.class);
     }
 }

src/main/java/run/halo/app/infra/utils/HaloUtils.java

@@ -4,8 +4,11 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.nio.charset.StandardCharsets;
 import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.lang3.StringUtils;
 import org.springframework.core.io.ClassPathResource;
+import org.springframework.http.HttpHeaders;
 import org.springframework.util.StreamUtils;
+import org.springframework.web.reactive.function.server.ServerRequest;
 
 /**
  * @author guqing
@@ -31,4 +34,20 @@ public class HaloUtils {
         }
     }
 
+    /**
+     * Gets user-agent from server request.
+     *
+     * @param request server request
+     * @return user-agent string if found, otherwise "unknown"
+     */
+    public static String userAgentFrom(ServerRequest request) {
+        HttpHeaders httpHeaders = request.headers().asHttpHeaders();
+        // https://en.wikipedia.org/wiki/User_agent
+        String userAgent = httpHeaders.getFirst(HttpHeaders.USER_AGENT);
+        if (StringUtils.isBlank(userAgent)) {
+            // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-CH-UA
+            userAgent = httpHeaders.getFirst("Sec-CH-UA");
+        }
+        return StringUtils.defaultString(userAgent, "unknown");
+    }
 }

src/main/java/run/halo/app/metrics/CounterMeterHandler.java

@@ -0,0 +1,137 @@
+package run.halo.app.metrics;
+
+import io.micrometer.core.instrument.Meter;
+import io.micrometer.core.instrument.MeterRegistry;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.DisposableBean;
+import org.springframework.boot.context.event.ApplicationReadyEvent;
+import org.springframework.context.event.EventListener;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Component;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+import run.halo.app.core.extension.Counter;
+import run.halo.app.extension.Metadata;
+import run.halo.app.extension.ReactiveExtensionClient;
+import run.halo.app.infra.utils.JsonUtils;
+
+/**
+ * Counter meter handler for {@link Counter}.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@Slf4j
+@Component
+public class CounterMeterHandler implements DisposableBean {
+
+    private final ReactiveExtensionClient client;
+    private final MeterRegistry meterRegistry;
+
+    public CounterMeterHandler(ReactiveExtensionClient client, MeterRegistry meterRegistry) {
+        this.client = client;
+        this.meterRegistry = meterRegistry;
+    }
+
+    /**
+     * Synchronize counter meters from {@link Counter}.
+     *
+     * @param event application ready event
+     */
+    @EventListener(ApplicationReadyEvent.class)
+    public Mono<Void> onApplicationReady(ApplicationReadyEvent event) {
+        return client.list(Counter.class, null, null)
+            .map(counter -> {
+                String name = counter.getMetadata().getName();
+                // visit counter
+                io.micrometer.core.instrument.Counter visitCounter =
+                    MeterUtils.visitCounter(meterRegistry, name);
+                visitCounter.increment(nullSafe(counter.getVisit()));
+
+                // upvote counter
+                io.micrometer.core.instrument.Counter upvoteCounter =
+                    MeterUtils.upvoteCounter(meterRegistry, name);
+                upvoteCounter.increment(nullSafe(counter.getUpvote()));
+
+                // total comment counter
+                io.micrometer.core.instrument.Counter totalCommentCounter =
+                    MeterUtils.totalCommentCounter(meterRegistry, name);
+                totalCommentCounter.increment(nullSafe(counter.getTotalComment()));
+
+                // approved comment counter
+                io.micrometer.core.instrument.Counter approvedCommentCounter =
+                    MeterUtils.approvedCommentCounter(meterRegistry, name);
+                approvedCommentCounter.increment(nullSafe(counter.getApprovedComment()));
+                return counter;
+            })
+            .then();
+    }
+
+    int nullSafe(Integer value) {
+        return Objects.requireNonNullElse(value, 0);
+    }
+
+    /**
+     * Synchronize memory counter meter to the database every minute.
+     */
+    @Scheduled(cron = "0 0/1 * * * ?")
+    public void counterPersistenceTask() {
+        log.debug("Regularly synchronize counter meters to the database.");
+        save().block();
+    }
+
+    Mono<Void> save() {
+        Map<String, List<Meter>> nameMeters = meterRegistry.getMeters().stream()
+            .filter(meter -> meter instanceof io.micrometer.core.instrument.Counter)
+            .filter(counter -> {
+                Meter.Id id = counter.getId();
+                return id.getTag(MeterUtils.METRICS_COMMON_TAG.getKey()) != null;
+            })
+            .collect(Collectors.groupingBy(meter -> meter.getId().getName()));
+        Stream<Mono<Counter>> monoStream = nameMeters.entrySet().stream()
+            .map(entry -> {
+                String name = entry.getKey();
+                List<Meter> meters = entry.getValue();
+                return client.fetch(Counter.class, name)
+                    .switchIfEmpty(Mono.defer(() -> {
+                        Counter counter = emptyCounter(name);
+                        return client.create(counter);
+                    }))
+                    .flatMap(counter -> {
+                        Counter oldCounter = JsonUtils.deepCopy(counter);
+                        counter.populateFrom(meters);
+                        if (oldCounter.equals(counter)) {
+                            return Mono.empty();
+                        }
+                        return Mono.just(counter);
+                    })
+                    .flatMap(client::update);
+            });
+        return Flux.fromStream(monoStream)
+            .flatMap(Function.identity())
+            .then();
+    }
+
+    static Counter emptyCounter(String name) {
+        Counter counter = new Counter();
+        counter.setMetadata(new Metadata());
+        counter.getMetadata().setName(name);
+        counter.setUpvote(0);
+        counter.setTotalComment(0);
+        counter.setApprovedComment(0);
+        counter.setVisit(0);
+        return counter;
+    }
+
+    @Override
+    public void destroy() {
+        log.debug("Persist counter meters to database before destroy...");
+        save().block();
+    }
+}

src/main/java/run/halo/app/metrics/CounterService.java

@@ -0,0 +1,12 @@
+package run.halo.app.metrics;
+
+import run.halo.app.core.extension.Counter;
+
+/**
+ * @author guqing
+ * @since 2.0.0
+ */
+public interface CounterService {
+
+    Counter getByName(String counterName);
+}

src/main/java/run/halo/app/metrics/CounterServiceImpl.java

@@ -0,0 +1,44 @@
+package run.halo.app.metrics;
+
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.Tag;
+import java.util.Collection;
+import org.springframework.stereotype.Service;
+import run.halo.app.core.extension.Counter;
+import run.halo.app.extension.Metadata;
+
+/**
+ * Counter service implementation.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@Service
+public class CounterServiceImpl implements CounterService {
+
+    private final MeterRegistry meterRegistry;
+
+    public CounterServiceImpl(MeterRegistry meterRegistry) {
+        this.meterRegistry = meterRegistry;
+    }
+
+    @Override
+    public Counter getByName(String counterName) {
+        Tag commonTag = MeterUtils.METRICS_COMMON_TAG;
+        Collection<io.micrometer.core.instrument.Counter> counters = meterRegistry.find(counterName)
+            .tag(commonTag.getKey(),
+                valueMatch -> commonTag.getValue().equals(valueMatch))
+            .counters();
+
+        Counter counter = emptyCounter(counterName);
+        counter.populateFrom(counters);
+        return counter;
+    }
+
+    private Counter emptyCounter(String name) {
+        Counter counter = new Counter();
+        counter.setMetadata(new Metadata());
+        counter.getMetadata().setName(name);
+        return counter;
+    }
+}

src/main/java/run/halo/app/metrics/MeterUtils.java

@@ -0,0 +1,111 @@
+package run.halo.app.metrics;
+
+import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.Tag;
+import io.micrometer.core.instrument.Tags;
+import org.apache.commons.lang3.StringUtils;
+import run.halo.app.extension.AbstractExtension;
+import run.halo.app.extension.GVK;
+
+/**
+ * Meter utils.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+public class MeterUtils {
+
+    public static final Tag METRICS_COMMON_TAG = Tag.of("metrics.halo.run", "true");
+    public static final String SCENE = "scene";
+    public static final String VISIT_SCENE = "visit";
+    public static final String UPVOTE_SCENE = "upvote";
+    public static final String TOTAL_COMMENT_SCENE = "total_comment";
+    public static final String APPROVED_COMMENT_SCENE = "approved_comment";
+
+    /**
+     * Build a counter name.
+     *
+     * @param group extension group
+     * @param plural extension plural
+     * @param name extension name
+     * @return counter name
+     */
+    public static String nameOf(String group, String plural, String name) {
+        if (StringUtils.isBlank(group)) {
+            return String.join("/", plural, name);
+        }
+        return String.join(".", plural, group) + "/" + name;
+    }
+
+    public static <T extends AbstractExtension> String nameOf(Class<T> clazz, String name) {
+        GVK annotation = clazz.getAnnotation(GVK.class);
+        return nameOf(annotation.group(), annotation.plural(), name);
+    }
+
+    public static Counter visitCounter(MeterRegistry registry, String name) {
+        return counter(registry, name, Tag.of(SCENE, VISIT_SCENE));
+    }
+
+    public static Counter upvoteCounter(MeterRegistry registry, String name) {
+        return counter(registry, name, Tag.of(SCENE, UPVOTE_SCENE));
+    }
+
+    public static Counter totalCommentCounter(MeterRegistry registry, String name) {
+        return counter(registry, name, Tag.of(SCENE, TOTAL_COMMENT_SCENE));
+    }
+
+    public static Counter approvedCommentCounter(MeterRegistry registry, String name) {
+        return counter(registry, name, Tag.of(SCENE, APPROVED_COMMENT_SCENE));
+    }
+
+    public static boolean isVisitCounter(Counter counter) {
+        String sceneValue = counter.getId().getTag(SCENE);
+        if (StringUtils.isBlank(sceneValue)) {
+            return false;
+        }
+        return VISIT_SCENE.equals(sceneValue);
+    }
+
+    public static boolean isUpvoteCounter(Counter counter) {
+        String sceneValue = counter.getId().getTag(SCENE);
+        if (StringUtils.isBlank(sceneValue)) {
+            return false;
+        }
+        return UPVOTE_SCENE.equals(sceneValue);
+    }
+
+    public static boolean isTotalCommentCounter(Counter counter) {
+        String sceneValue = counter.getId().getTag(SCENE);
+        if (StringUtils.isBlank(sceneValue)) {
+            return false;
+        }
+        return TOTAL_COMMENT_SCENE.equals(sceneValue);
+    }
+
+    public static boolean isApprovedCommentCounter(Counter counter) {
+        String sceneValue = counter.getId().getTag(SCENE);
+        if (StringUtils.isBlank(sceneValue)) {
+            return false;
+        }
+        return APPROVED_COMMENT_SCENE.equals(sceneValue);
+    }
+
+    /**
+     * Build a {@link Counter} for halo extension.
+     *
+     * @param registry meter registry
+     * @param name counter name,build by {@link #nameOf(String, String, String)}
+     * @return counter find by name from registry if exists, otherwise create a new one.
+     */
+    private static Counter counter(MeterRegistry registry, String name, Tag... tags) {
+        Tags withTags = Tags.of(METRICS_COMMON_TAG).and(tags);
+        Counter counter = registry.find(name)
+            .tags(withTags)
+            .counter();
+        if (counter == null) {
+            return registry.counter(name, withTags);
+        }
+        return counter;
+    }
+}

src/main/java/run/halo/app/metrics/VisitLogWriter.java

@@ -0,0 +1,171 @@
+package run.halo.app.metrics;
+
+import java.io.BufferedOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+import java.time.Instant;
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.ReentrantLock;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.lang3.exception.ExceptionUtils;
+import org.springframework.beans.factory.DisposableBean;
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.stereotype.Component;
+import run.halo.app.infra.properties.HaloProperties;
+import run.halo.app.infra.utils.FileUtils;
+
+/**
+ * Visit log writer.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@Slf4j
+@Component
+public class VisitLogWriter implements InitializingBean, DisposableBean {
+    private static final String LOG_FILE_NAME = "visits.log";
+    private static final String LOG_FILE_LOCATION = "logs";
+    private final AsyncLogWriter asyncLogWriter;
+    private volatile boolean interruptThread = false;
+
+    private final Path logFilePath;
+
+    private VisitLogWriter(HaloProperties haloProperties) throws IOException {
+        Path logsPath = haloProperties.getWorkDir()
+            .resolve(LOG_FILE_LOCATION);
+        if (!Files.exists(logsPath)) {
+            Files.createDirectories(logsPath);
+        }
+        this.logFilePath = logsPath.resolve(LOG_FILE_NAME);
+        this.asyncLogWriter = new AsyncLogWriter(logFilePath);
+    }
+
+    public synchronized void log(String logMsg) {
+        asyncLogWriter.put(logMsg);
+    }
+
+    public Path getLogFilePath() {
+        return logFilePath;
+    }
+
+    void start() {
+        log.debug("Starting write visit log...");
+        Thread thread = new Thread(() -> {
+            while (!interruptThread) {
+                asyncLogWriter.writeLog();
+            }
+        }, "visits-log-writer");
+        thread.start();
+    }
+
+    @Override
+    public void afterPropertiesSet() throws Exception {
+        start();
+    }
+
+    @Override
+    public void destroy() throws Exception {
+        asyncLogWriter.close();
+        interruptThread = true;
+    }
+
+    static class AsyncLogWriter {
+        private static final int MAX_LOG_SIZE = 10000;
+        private static final int BATCH_SIZE = 10;
+        private final ReentrantLock lock = new ReentrantLock();
+        private final Condition fullCondition = lock.newCondition();
+        private final Condition emptyCondition = lock.newCondition();
+        private final BufferedOutputStream writer;
+        private final Deque<String> logQueue;
+        private final AtomicInteger logBatch = new AtomicInteger(0);
+
+        public AsyncLogWriter(Path logFilePath) {
+            OutputStream outputStream;
+            try {
+                outputStream = Files.newOutputStream(logFilePath,
+                    StandardOpenOption.CREATE,
+                    StandardOpenOption.APPEND);
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+            this.writer = new BufferedOutputStream(outputStream);
+            this.logQueue = new ArrayDeque<>();
+        }
+
+        public void writeLog() {
+            lock.lock();
+            try {
+                // queue is empty, wait for new log
+                while (logQueue.isEmpty()) {
+                    try {
+                        emptyCondition.await();
+                    } catch (InterruptedException e) {
+                        e.printStackTrace();
+                    }
+                }
+                String logMessage = logQueue.poll();
+                writeToDisk(logMessage);
+                log.debug("Consumption visit log message: [{}]", logMessage);
+                // signal log producer
+                fullCondition.signal();
+            } finally {
+                lock.unlock();
+            }
+        }
+
+        void writeToDisk(String logMsg) {
+            String format = String.format("%s %s\n", Instant.now(), logMsg);
+            lock.lock();
+            try {
+                writer.write(format.getBytes(), 0, format.length());
+                int size = logBatch.incrementAndGet();
+                if (size >= BATCH_SIZE) {
+                    writer.flush();
+                    logBatch.set(0);
+                }
+            } catch (IOException e) {
+                log.warn("Record access log failure: ", ExceptionUtils.getRootCause(e));
+            } finally {
+                lock.unlock();
+            }
+        }
+
+        public void put(String logMessage) {
+            lock.lock();
+            try {
+                while (logQueue.size() == MAX_LOG_SIZE) {
+                    try {
+                        log.debug("Queue full, producer thread waiting...");
+                        fullCondition.await();
+                    } catch (InterruptedException e) {
+                        e.printStackTrace();
+                    }
+                }
+                // add log message to queue tail
+                logQueue.add(logMessage);
+                log.info("Production a log messages [{}]", logMessage);
+                // signal consumer thread
+                emptyCondition.signal();
+            } finally {
+                lock.unlock();
+            }
+        }
+
+        public void close() {
+            if (writer != null) {
+                try {
+                    writer.flush();
+                } catch (IOException e) {
+                    // ignore this
+                }
+                FileUtils.closeQuietly(writer);
+            }
+        }
+    }
+}

src/main/java/run/halo/app/theme/dialect/GlobalHeadInjectionProcessor.java

@@ -68,7 +68,7 @@ public class GlobalHeadInjectionProcessor extends AbstractElementModelProcessor
             getTemplateHeadProcessors(appCtx);
         for (TemplateHeadProcessor processor : templateHeadProcessors) {
             processor.process(context, modelToInsert, structureHandler)
-                .subscribe();
+                .block();
         }
 
         // add to target model

src/main/java/run/halo/app/theme/dialect/HaloTrackerProcessor.java

@@ -0,0 +1,63 @@
+package run.halo.app.theme.dialect;
+
+import org.apache.commons.lang3.StringUtils;
+import org.springframework.stereotype.Component;
+import org.thymeleaf.context.ITemplateContext;
+import org.thymeleaf.model.IModel;
+import org.thymeleaf.model.IModelFactory;
+import org.thymeleaf.processor.element.IElementModelStructureHandler;
+import reactor.core.publisher.Mono;
+import run.halo.app.extension.GroupVersionKind;
+import run.halo.app.infra.properties.HaloProperties;
+import run.halo.app.infra.utils.PathUtils;
+
+/**
+ * Get {@link GroupVersionKind} and {@code plural} from the view model to construct tracker
+ * script tag and insert it into the head tag.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@Component
+public class HaloTrackerProcessor implements TemplateHeadProcessor {
+
+    private final HaloProperties haloProperties;
+
+    public HaloTrackerProcessor(HaloProperties haloProperties) {
+        this.haloProperties = haloProperties;
+    }
+
+    @Override
+    public Mono<Void> process(ITemplateContext context, IModel model,
+        IElementModelStructureHandler structureHandler) {
+        final IModelFactory modelFactory = context.getModelFactory();
+        return Mono.just(getTrackerScript(context))
+            .filter(StringUtils::isNotBlank)
+            .map(trackerScript -> {
+                model.add(modelFactory.createText(trackerScript));
+                return trackerScript;
+            })
+            .then();
+    }
+
+    private String getTrackerScript(ITemplateContext context) {
+        String resourceName = (String) context.getVariable("name");
+        String externalUrl = haloProperties.getExternalUrl().getPath();
+        Object groupVersionKind = context.getVariable("groupVersionKind");
+        Object plural = context.getVariable("plural");
+        if (groupVersionKind == null || plural == null) {
+            return StringUtils.EMPTY;
+        }
+        if (!(groupVersionKind instanceof GroupVersionKind gvk)) {
+            return StringUtils.EMPTY;
+        }
+        return trackerScript(externalUrl, gvk.group(), (String) plural, resourceName);
+    }
+
+    private String trackerScript(String externalUrl, String group, String plural, String name) {
+        String jsSrc = PathUtils.combinePath(externalUrl, "/halo-tracker.js");
+        return """
+            <script async defer src="%s" data-group="%s" data-plural="%s" data-name="%s"></script>
+            """.formatted(jsSrc, group, plural, name);
+    }
+}

src/main/java/run/halo/app/theme/endpoint/CommentFinderEndpoint.java

@@ -26,13 +26,13 @@ import run.halo.app.content.comment.ReplyRequest;
 import run.halo.app.content.comment.ReplyService;
 import run.halo.app.core.extension.Comment;
 import run.halo.app.core.extension.Reply;
-import run.halo.app.core.extension.endpoint.CommentEndpoint;
 import run.halo.app.core.extension.endpoint.CustomEndpoint;
 import run.halo.app.extension.GroupVersion;
 import run.halo.app.extension.ListResult;
 import run.halo.app.extension.Ref;
 import run.halo.app.extension.router.IListRequest;
 import run.halo.app.extension.router.QueryParamBuildUtil;
+import run.halo.app.infra.utils.HaloUtils;
 import run.halo.app.infra.utils.IpAddressUtils;
 import run.halo.app.theme.finders.CommentFinder;
 import run.halo.app.theme.finders.vo.CommentVo;
@@ -145,7 +145,7 @@ public class CommentFinderEndpoint implements CustomEndpoint {
             .flatMap(commentRequest -> {
                 Comment comment = commentRequest.toComment();
                 comment.getSpec().setIpAddress(IpAddressUtils.getIpAddress(request));
-                comment.getSpec().setUserAgent(CommentEndpoint.userAgentFrom(request));
+                comment.getSpec().setUserAgent(HaloUtils.userAgentFrom(request));
                 return commentService.create(comment);
             })
             .flatMap(comment -> ServerResponse.ok().bodyValue(comment));
@@ -157,7 +157,7 @@ public class CommentFinderEndpoint implements CustomEndpoint {
             .flatMap(replyRequest -> {
                 Reply reply = replyRequest.toReply();
                 reply.getSpec().setIpAddress(IpAddressUtils.getIpAddress(request));
-                reply.getSpec().setUserAgent(CommentEndpoint.userAgentFrom(request));
+                reply.getSpec().setUserAgent(HaloUtils.userAgentFrom(request));
                 return replyService.create(commentName, reply);
             })
             .flatMap(comment -> ServerResponse.ok().bodyValue(comment));

src/main/java/run/halo/app/theme/finders/impl/PostFinderImpl.java

@@ -10,9 +10,12 @@ import org.apache.commons.lang3.ObjectUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.springframework.lang.NonNull;
 import run.halo.app.content.ContentService;
+import run.halo.app.core.extension.Counter;
 import run.halo.app.core.extension.Post;
 import run.halo.app.extension.ListResult;
 import run.halo.app.extension.ReactiveExtensionClient;
+import run.halo.app.metrics.CounterService;
+import run.halo.app.metrics.MeterUtils;
 import run.halo.app.theme.finders.CategoryFinder;
 import run.halo.app.theme.finders.ContributorFinder;
 import run.halo.app.theme.finders.Finder;
@@ -22,6 +25,7 @@ import run.halo.app.theme.finders.vo.CategoryVo;
 import run.halo.app.theme.finders.vo.ContentVo;
 import run.halo.app.theme.finders.vo.Contributor;
 import run.halo.app.theme.finders.vo.PostVo;
+import run.halo.app.theme.finders.vo.StatsVo;
 import run.halo.app.theme.finders.vo.TagVo;
 
 /**
@@ -47,16 +51,19 @@ public class PostFinderImpl implements PostFinder {
 
     private final ContributorFinder contributorFinder;
 
+    private final CounterService counterService;
+
     public PostFinderImpl(ReactiveExtensionClient client,
         ContentService contentService,
         TagFinder tagFinder,
         CategoryFinder categoryFinder,
-        ContributorFinder contributorFinder) {
+        ContributorFinder contributorFinder, CounterService counterService) {
         this.client = client;
         this.contentService = contentService;
         this.tagFinder = tagFinder;
         this.categoryFinder = categoryFinder;
         this.contributorFinder = contributorFinder;
+        this.counterService = counterService;
     }
 
     @Override
@@ -116,10 +123,23 @@ public class PostFinderImpl implements PostFinder {
         }
         List<PostVo> postVos = list.get()
             .map(this::getPostVo)
+            .peek(this::populateStats)
             .toList();
         return new ListResult<>(list.getPage(), list.getSize(), list.getTotal(), postVos);
     }
 
+    private void populateStats(PostVo postVo) {
+        Counter counter =
+            counterService.getByName(MeterUtils.nameOf(Post.class, postVo.getMetadata()
+                .getName()));
+        StatsVo statsVo = StatsVo.builder()
+            .visit(counter.getVisit())
+            .upvote(counter.getUpvote())
+            .comment(counter.getApprovedComment())
+            .build();
+        postVo.setStats(statsVo);
+    }
+
     private PostVo getPostVo(@NonNull Post post) {
         List<TagVo> tags = tagFinder.getByNames(post.getSpec().getTags());
         List<CategoryVo> categoryVos = categoryFinder.getByNames(post.getSpec().getCategories());
@@ -129,6 +149,7 @@ public class PostFinderImpl implements PostFinder {
         postVo.setCategories(categoryVos);
         postVo.setTags(tags);
         postVo.setContributors(contributors);
+        populateStats(postVo);
         return postVo;
     }
 

src/main/java/run/halo/app/theme/finders/impl/SinglePageFinderImpl.java

@@ -8,16 +8,20 @@ import java.util.function.Function;
 import java.util.function.Predicate;
 import org.apache.commons.lang3.ObjectUtils;
 import run.halo.app.content.ContentService;
+import run.halo.app.core.extension.Counter;
 import run.halo.app.core.extension.Post;
 import run.halo.app.core.extension.SinglePage;
 import run.halo.app.extension.ListResult;
 import run.halo.app.extension.ReactiveExtensionClient;
+import run.halo.app.metrics.CounterService;
+import run.halo.app.metrics.MeterUtils;
 import run.halo.app.theme.finders.ContributorFinder;
 import run.halo.app.theme.finders.Finder;
 import run.halo.app.theme.finders.SinglePageFinder;
 import run.halo.app.theme.finders.vo.ContentVo;
 import run.halo.app.theme.finders.vo.Contributor;
 import run.halo.app.theme.finders.vo.SinglePageVo;
+import run.halo.app.theme.finders.vo.StatsVo;
 
 /**
  * A default implementation of {@link SinglePage}.
@@ -39,11 +43,14 @@ public class SinglePageFinderImpl implements SinglePageFinder {
 
     private final ContributorFinder contributorFinder;
 
+    private final CounterService counterService;
+
     public SinglePageFinderImpl(ReactiveExtensionClient client, ContentService contentService,
-        ContributorFinder contributorFinder) {
+        ContributorFinder contributorFinder, CounterService counterService) {
         this.client = client;
         this.contentService = contentService;
         this.contributorFinder = contributorFinder;
+        this.counterService = counterService;
     }
 
     @Override
@@ -58,6 +65,7 @@ public class SinglePageFinderImpl implements SinglePageFinder {
         SinglePageVo pageVo = SinglePageVo.from(page);
         pageVo.setContributors(contributors);
         pageVo.setContent(content(pageName));
+        populateStats(pageVo);
         return pageVo;
     }
 
@@ -79,16 +87,29 @@ public class SinglePageFinderImpl implements SinglePageFinder {
         if (list == null) {
             return new ListResult<>(0, 0, 0, List.of());
         }
-        List<SinglePageVo> postVos = list.get()
+        List<SinglePageVo> pageVos = list.get()
             .map(sp -> {
                 List<Contributor> contributors =
                     contributorFinder.getContributors(sp.getStatus().getContributors());
                 SinglePageVo pageVo = SinglePageVo.from(sp);
                 pageVo.setContributors(contributors);
+                populateStats(pageVo);
                 return pageVo;
             })
             .toList();
-        return new ListResult<>(list.getPage(), list.getSize(), list.getTotal(), postVos);
+        return new ListResult<>(list.getPage(), list.getSize(), list.getTotal(), pageVos);
+    }
+
+    void populateStats(SinglePageVo pageVo) {
+        String name = pageVo.getMetadata().getName();
+        Counter counter =
+            counterService.getByName(MeterUtils.nameOf(SinglePage.class, name));
+        StatsVo statsVo = StatsVo.builder()
+            .visit(counter.getVisit())
+            .upvote(counter.getUpvote())
+            .comment(counter.getApprovedComment())
+            .build();
+        pageVo.setStats(statsVo);
     }
 
     static Comparator<SinglePage> defaultComparator() {

src/main/java/run/halo/app/theme/finders/vo/PostVo.java

@@ -35,6 +35,8 @@ public class PostVo {
 
     private List<Contributor> contributors;
 
+    private StatsVo stats;
+
     /**
      * Convert {@link Post} to {@link PostVo}.
      *

src/main/java/run/halo/app/theme/finders/vo/SinglePageVo.java

@@ -29,6 +29,8 @@ public class SinglePageVo {
 
     private ContentVo content;
 
+    private StatsVo stats;
+
     private List<Contributor> contributors;
 
     /**

src/main/java/run/halo/app/theme/finders/vo/StatsVo.java

@@ -0,0 +1,21 @@
+package run.halo.app.theme.finders.vo;
+
+import lombok.Builder;
+import lombok.Value;
+
+/**
+ * Stats value object.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@Value
+@Builder
+public class StatsVo {
+
+    Integer visit;
+
+    Integer upvote;
+
+    Integer comment;
+}

src/main/java/run/halo/app/theme/router/strategy/PostRouteStrategy.java

@@ -21,6 +21,7 @@ import reactor.core.publisher.Mono;
 import reactor.core.scheduler.Schedulers;
 import run.halo.app.content.permalinks.ExtensionLocator;
 import run.halo.app.core.extension.Post;
+import run.halo.app.extension.GVK;
 import run.halo.app.extension.GroupVersionKind;
 import run.halo.app.theme.DefaultTemplateEnum;
 import run.halo.app.theme.finders.PostFinder;
@@ -49,7 +50,7 @@ public class PostRouteStrategy implements TemplateRouterStrategy {
     public RouterFunction<ServerResponse> getRouteFunction(String template, String pattern) {
         PostRequestParamPredicate postParamPredicate =
             new PostRequestParamPredicate(pattern);
-
+        GVK gvk = Post.class.getAnnotation(GVK.class);
         if (postParamPredicate.isQueryParamPattern()) {
             String paramName = postParamPredicate.getParamName();
             String placeholderName = postParamPredicate.getPlaceholderName();
@@ -72,10 +73,14 @@ public class PostRouteStrategy implements TemplateRouterStrategy {
                     if (name == null) {
                         return ServerResponse.notFound().build();
                     }
+                    GroupVersionKind groupVersionKind =
+                        new GroupVersionKind(gvk.group(), gvk.version(), gvk.kind());
                     return ServerResponse.ok()
                         .render(DefaultTemplateEnum.POST.getValue(),
                             Map.of(PostRequestParamPredicate.NAME_PARAM, name,
-                                "post", postByName(name))
+                                "post", postByName(name),
+                                "groupVersionKind", groupVersionKind,
+                                "plural", gvk.plural())
                         );
                 });
         }
@@ -95,6 +100,8 @@ public class PostRouteStrategy implements TemplateRouterStrategy {
                         model.putAll(pathMatchInfo.getUriVariables());
                     }
                     model.put("post", postByName(locator.name()));
+                    model.put("groupVersionKind", locator.gvk());
+                    model.put("plural", gvk.plural());
                     return ServerResponse.ok()
                         .render(DefaultTemplateEnum.POST.getValue(), model);
                 });

src/main/java/run/halo/app/theme/router/strategy/SinglePageRouteStrategy.java

@@ -14,6 +14,7 @@ import org.springframework.web.reactive.function.server.ServerResponse;
 import reactor.core.publisher.Mono;
 import reactor.core.scheduler.Schedulers;
 import run.halo.app.core.extension.SinglePage;
+import run.halo.app.extension.GVK;
 import run.halo.app.extension.GroupVersionKind;
 import run.halo.app.theme.DefaultTemplateEnum;
 import run.halo.app.theme.finders.SinglePageFinder;
@@ -60,10 +61,17 @@ public class SinglePageRouteStrategy implements TemplateRouterStrategy {
                 return ServerResponse.ok()
                     .render(DefaultTemplateEnum.SINGLE_PAGE.getValue(),
                         Map.of("name", name,
+                            "groupVersionKind", gvk,
+                            "plural", getPlural(),
                             "singlePage", singlePageByName(name)));
             });
     }
 
+    private String getPlural() {
+        GVK annotation = SinglePage.class.getAnnotation(GVK.class);
+        return annotation.plural();
+    }
+
     private Mono<SinglePageVo> singlePageByName(String name) {
         return Mono.defer(() -> Mono.just(singlePageFinder.getByName(name)))
             .publishOn(Schedulers.boundedElastic());

src/main/resources/extensions/role-template-anonymous.yaml

@@ -9,3 +9,8 @@ rules:
   - apiGroups: [ "api.halo.run" ]
     resources: [ "comments", "comments/reply" ]
     verbs: [ "create", "get", "list" ]
+  - apiGroups: [ "api.halo.run" ]
+    resources: [ "*" ]
+    verbs: [ "*" ]
+  - nonResourceURLs: [ "/apis/api.halo.run/v1alpha1/trackers/counter" ]
+    verbs: [ "post" ]

src/main/resources/extensions/role-template-authenticated.yaml

@@ -49,3 +49,15 @@ rules:
     resources: [ "users/password" ]
     resourceNames: [ "-" ]
     verbs: [ "update" ]
+---
+apiVersion: v1alpha1
+kind: "Role"
+metadata:
+  name: role-template-stats
+  labels:
+    halo.run/role-template: "true"
+    halo.run/hidden: "true"
+rules:
+  - apiGroups: [ "api.console.halo.run" ]
+    resources: [ "stats" ]
+    verbs: [ "get", "list" ]

src/main/resources/static/halo-tracker.js

@@ -0,0 +1 @@
+!function(){"use strict";!function(t){var e=t.screen,r=e.width,n=e.height,a=t.navigator.language,o=t.location,i=t.localStorage,c=t.document,u=t.history,l=o.hostname,s=o.pathname,p=o.search,f=c.currentScript;if(f){var h=function(t,e,r){var n=t[e];return function(){for(var e=[],a=arguments.length;a--;)e[a]=arguments[a];return r.apply(null,e),n.apply(t,e)}},d=function(){return i&&i.getItem("haloTracker.disabled")||T&&function(){var e=t.doNotTrack,r=t.navigator,n=t.external,a="msTrackingProtectionEnabled",o=e||r.doNotTrack||r.msDoNotTrack||n&&a in n&&n[a]();return"1"==o||"yes"===o}()||j&&!w.includes(l)},g="data-",v=f.getAttribute.bind(f),m=v(g+"group")||"",k=v(g+"plural"),y=v(g+"name"),S=v(g+"host-url"),b="false"!==v(g+"auto-track"),T=v(g+"do-not-track"),j=v(g+"domains")||"",w=j.split(",").map((function(t){return t.trim()})),E=(S?S.replace(/\/$/,""):f.src.split("/").slice(0,-1).join("/"))+"/apis/api.halo.run/v1alpha1/trackers/counter",N=r+"x"+n,O=""+s+p,x=c.referrer,P=function(t,e){return void 0===t&&(t=O),void 0===e&&(e=x),function(t){if(!d())return fetch(E,{method:"POST",body:JSON.stringify(Object.assign({},t)),headers:{"Content-Type":"application/json"}}).then((function(t){return t.text()})).then((function(t){console.debug("Visit count:",t)}))}((r={group:m,plural:k,name:y,hostname:l,screen:N,language:a,url:O},n={url:t,referrer:e},Object.keys(n).forEach((function(t){void 0!==n[t]&&(r[t]=n[t])})),r));var r,n},V=function(t,e,r){if(r){x=O;var n=r.toString();(O="http"===n.substring(0,4)?"/"+n.split("/").splice(3).join("/"):n)!==x&&P()}};if(!t.haloTracker){var A=function(t){return trackEvent(t)};A.trackView=P,t.haloTracker=A}if(b&&!d()){u.pushState=h(u,"pushState",V),u.replaceState=h(u,"replaceState",V);var C=function(){"complete"===c.readyState&&P()};c.addEventListener("readystatechange",C,!0),C()}}}(window)}();

src/test/java/run/halo/app/content/impl/PostServiceImplTest.java

@@ -5,9 +5,9 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 import java.util.List;
 import java.util.Map;
-import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 import org.springframework.util.LinkedMultiValueMap;
@@ -32,13 +32,9 @@ class PostServiceImplTest {
     @Mock
     private ContentService contentService;
 
+    @InjectMocks
     private PostServiceImpl postService;
 
-    @BeforeEach
-    void setUp() {
-        postService = new PostServiceImpl(contentService, client);
-    }
-
     @Test
     void listPredicate() {
         MultiValueMap<String, String> multiValueMap = new LinkedMultiValueMap<>();

src/test/java/run/halo/app/core/extension/endpoint/UserEndpointTest.java

@@ -38,6 +38,7 @@ import run.halo.app.extension.ReactiveExtensionClient;
 import run.halo.app.extension.exception.ExtensionNotFoundException;
 import run.halo.app.infra.SystemConfigurableEnvironmentFetcher;
 import run.halo.app.infra.utils.JsonUtils;
+import run.halo.app.metrics.CounterMeterHandler;
 
 @SpringBootTest
 @AutoConfigureWebTestClient
@@ -56,6 +57,9 @@ class UserEndpointTest {
     @MockBean
     UserService userService;
 
+    @MockBean
+    CounterMeterHandler counterMeterHandler;
+
     @MockBean
     SystemConfigurableEnvironmentFetcher environmentFetcher;
 

src/test/java/run/halo/app/core/extension/reconciler/CommentReconcilerTest.java

@@ -6,24 +6,37 @@ import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.lenient;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
 
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
 import java.time.Duration;
 import java.time.Instant;
+import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.ArgumentCaptor;
-import org.mockito.InjectMocks;
 import org.mockito.Mock;
+import org.mockito.Mockito;
 import org.mockito.junit.jupiter.MockitoExtension;
 import run.halo.app.core.extension.Comment;
+import run.halo.app.core.extension.Post;
 import run.halo.app.core.extension.Reply;
 import run.halo.app.extension.ExtensionClient;
+import run.halo.app.extension.GroupVersionKind;
 import run.halo.app.extension.Metadata;
+import run.halo.app.extension.Ref;
+import run.halo.app.extension.Scheme;
+import run.halo.app.extension.SchemeManager;
 import run.halo.app.extension.controller.Reconciler;
+import run.halo.app.metrics.MeterUtils;
 
 /**
  * Tests for {@link CommentReconciler}.
@@ -37,11 +50,19 @@ class CommentReconcilerTest {
     @Mock
     private ExtensionClient client;
 
-    @InjectMocks
+    private final MeterRegistry meterRegistry = new SimpleMeterRegistry();
+    @Mock
+    SchemeManager schemeManager;
+
     private CommentReconciler commentReconciler;
 
     private final Instant now = Instant.now();
 
+    @BeforeEach
+    void setUp() {
+        commentReconciler = new CommentReconciler(client, meterRegistry, schemeManager);
+    }
+
     @Test
     void reconcile() {
         Comment comment = new Comment();
@@ -112,6 +133,94 @@ class CommentReconcilerTest {
             .contains(CommentReconciler.FINALIZER_NAME)).isFalse();
     }
 
+    @Test
+    void reconcileCommentCount() {
+        when(client.list(eq(Comment.class), any(), any()))
+            .thenReturn(commentList());
+        when(client.fetch(eq(Comment.class), eq("test")))
+            .thenReturn(Optional.of(getComment("test")));
+        lenient().when(client.list(eq(Reply.class), any(), any()))
+            .thenReturn(List.of());
+
+        Ref ref = getRef();
+        GroupVersionKind groupVersionKind =
+            new GroupVersionKind(ref.getGroup(), ref.getVersion(), ref.getKind());
+        Scheme scheme = new Scheme(Post.class, groupVersionKind, "posts", "post",
+            Mockito.mock(ObjectNode.class));
+        when(schemeManager.fetch(any())).thenReturn(Optional.of(scheme));
+
+        String fakePostCounterName =
+            MeterUtils.nameOf(ref.getGroup(), scheme.plural(), "fake-post");
+        String testPostCounterName =
+            MeterUtils.nameOf(ref.getGroup(), scheme.plural(), "test-post");
+
+        Counter approvedCommentCounter =
+            MeterUtils.approvedCommentCounter(meterRegistry, fakePostCounterName);
+        approvedCommentCounter.increment(5);
+
+        assertThat(approvedCommentCounter.count()).isEqualTo(5.0);
+
+        Counter testPostCounter =
+            MeterUtils.approvedCommentCounter(meterRegistry, testPostCounterName);
+        testPostCounter.increment(0);
+        assertThat(testPostCounter.count()).isEqualTo(0.0);
+
+        Counter totalCommentCounter =
+            MeterUtils.totalCommentCounter(meterRegistry, fakePostCounterName);
+        totalCommentCounter.increment(8);
+
+        commentReconciler.reconcile(new Reconciler.Request("test"));
+        assertThat(approvedCommentCounter.count()).isEqualTo(3.0);
+        assertThat(testPostCounter.count()).isEqualTo(1.0);
+        assertThat(totalCommentCounter.count()).isEqualTo(5.0);
+    }
+
+    List<Comment> commentList() {
+        final List<Comment> comments = new ArrayList<>();
+        final Comment commentA = getComment("A");
+        final Comment commentB = getComment("B");
+        final Comment commentC = getComment("C");
+
+        Comment commentD = getComment("D");
+        commentD.getSpec().getSubjectRef().setName("test-post");
+
+        final Comment commentE = getComment("E");
+        commentE.getSpec().setApproved(false);
+
+        final Comment commentF = getComment("F");
+        commentF.getSpec().setApproved(false);
+
+        comments.add(commentA);
+        comments.add(commentB);
+        comments.add(commentC);
+        comments.add(commentD);
+        comments.add(commentE);
+        comments.add(commentF);
+        return comments;
+    }
+
+    private Comment getComment(String name) {
+        final Ref ref = getRef();
+        Comment comment = new Comment();
+        comment.setMetadata(new Metadata());
+        comment.getMetadata().setName(name);
+        comment.setSpec(new Comment.CommentSpec());
+        comment.getSpec().setSubjectRef(ref);
+        comment.getSpec().setApproved(true);
+        comment.getSpec().setLastReadTime(now.plusSeconds(5));
+        comment.setStatus(new Comment.CommentStatus());
+        return comment;
+    }
+
+    private static Ref getRef() {
+        Ref ref = new Ref();
+        ref.setGroup("content.halo.run");
+        ref.setVersion("v1alpha1");
+        ref.setKind("Post");
+        ref.setName("fake-post");
+        return ref;
+    }
+
     List<Reply> replyList() {
         Reply replyA = new Reply();
         replyA.setMetadata(new Metadata());

src/test/java/run/halo/app/metrics/CounterMeterHandlerTest.java

@@ -0,0 +1,108 @@
+package run.halo.app.metrics;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.Mockito;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.boot.context.event.ApplicationReadyEvent;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
+import run.halo.app.core.extension.Counter;
+import run.halo.app.core.extension.Post;
+import run.halo.app.extension.Metadata;
+import run.halo.app.extension.ReactiveExtensionClient;
+
+/**
+ * Tests for {@link CounterMeterHandler}.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+@ExtendWith(MockitoExtension.class)
+class CounterMeterHandlerTest {
+
+    @Mock
+    private ReactiveExtensionClient client;
+
+    private final String counterName = MeterUtils.nameOf(Post.class, "fake-post");
+
+    @InjectMocks
+    private CounterMeterHandler counterMeterHandler;
+
+    private MeterRegistry meterRegistry;
+
+    @BeforeEach
+    void setUp() {
+        meterRegistry = new SimpleMeterRegistry();
+        counterMeterHandler = new CounterMeterHandler(client, meterRegistry);
+    }
+
+    @Test
+    void onApplicationReady() {
+        Counter counter = new Counter();
+        counter.setMetadata(new Metadata());
+        counter.getMetadata().setName(counterName);
+        counter.setVisit(1);
+        counter.setUpvote(3);
+        counter.setTotalComment(5);
+        counter.setApprovedComment(2);
+
+        Mockito.when(client.list(eq(Counter.class), any(), any()))
+            .thenReturn(Flux.just(counter));
+
+        counterMeterHandler.onApplicationReady(Mockito.mock(ApplicationReadyEvent.class))
+            .as(StepVerifier::create)
+            .verifyComplete();
+
+        assertThat((int) meterRegistry.find(counterName)
+            .tag(MeterUtils.SCENE, value -> value.equals(MeterUtils.VISIT_SCENE))
+            .counter().count()).isEqualTo(counter.getVisit());
+
+        assertThat((int) meterRegistry.find(counterName)
+            .tag(MeterUtils.SCENE, value -> value.equals(MeterUtils.UPVOTE_SCENE))
+            .counter().count()).isEqualTo(counter.getUpvote());
+        assertThat((int) meterRegistry.find(counterName)
+            .tag(MeterUtils.SCENE, value -> value.equals(MeterUtils.TOTAL_COMMENT_SCENE))
+            .counter().count()).isEqualTo(counter.getTotalComment());
+        assertThat((int) meterRegistry.find(counterName)
+            .tag(MeterUtils.SCENE, value -> value.equals(MeterUtils.APPROVED_COMMENT_SCENE))
+            .counter().count()).isEqualTo(counter.getApprovedComment());
+    }
+
+    @Test
+    void save() {
+        MeterUtils.visitCounter(meterRegistry, counterName).increment(2);
+        MeterUtils.upvoteCounter(meterRegistry, counterName).increment(3);
+
+        Mockito.when(client.create(any()))
+            .thenReturn(Mono.just(CounterMeterHandler.emptyCounter(counterName)));
+        Mockito.when(client.fetch(eq(Counter.class), eq(counterName)))
+            .thenReturn(Mono.empty());
+        Mockito.when(client.update(any(Counter.class)))
+            .thenAnswer(a -> {
+                ArgumentCaptor<Counter> captor =
+                    ArgumentCaptor.forClass(Counter.class);
+                Mockito.verify(client, Mockito.times(1)).update(captor.capture());
+                Counter value = captor.getValue();
+                assertThat(value.getVisit()).isEqualTo(2);
+                assertThat(value.getUpvote()).isEqualTo(3);
+                assertThat(value.getTotalComment()).isEqualTo(0);
+                assertThat(value.getApprovedComment()).isEqualTo(0);
+                return Mono.just(value);
+            });
+        counterMeterHandler.save()
+            .as(StepVerifier::create)
+            .verifyComplete();
+    }
+}

src/test/java/run/halo/app/metrics/CounterServiceImplTest.java

@@ -0,0 +1,41 @@
+package run.halo.app.metrics;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import run.halo.app.core.extension.Post;
+
+/**
+ * Tests for {@link CounterServiceImpl}.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+class CounterServiceImplTest {
+
+    private CounterServiceImpl counterService;
+
+    @BeforeEach
+    void setUp() {
+        SimpleMeterRegistry simpleMeterRegistry = new SimpleMeterRegistry();
+        counterService = new CounterServiceImpl(simpleMeterRegistry);
+        String counterName = MeterUtils.nameOf(Post.class, "fake-post");
+        MeterUtils.visitCounter(simpleMeterRegistry,
+            counterName).increment();
+
+        MeterUtils.approvedCommentCounter(simpleMeterRegistry, counterName)
+            .increment(2);
+    }
+
+    @Test
+    void getByName() {
+        run.halo.app.core.extension.Counter counter =
+            counterService.getByName(MeterUtils.nameOf(Post.class, "fake-post"));
+        assertThat(counter.getVisit()).isEqualTo(1);
+        assertThat(counter.getUpvote()).isEqualTo(0);
+        assertThat(counter.getTotalComment()).isEqualTo(0);
+        assertThat(counter.getApprovedComment()).isEqualTo(2);
+    }
+}

src/test/java/run/halo/app/metrics/MeterUtilsTest.java

@@ -0,0 +1,119 @@
+package run.halo.app.metrics;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.Meter;
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.search.RequiredSearch;
+import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import org.junit.jupiter.api.Test;
+import run.halo.app.core.extension.Post;
+
+/**
+ * Tests for {@link MeterUtils}.
+ *
+ * @author guqing
+ * @since 2.0.0
+ */
+class MeterUtilsTest {
+
+    @Test
+    void nameOf() {
+        String s = MeterUtils.nameOf(Post.class, "fake-post");
+        assertThat(s).isEqualTo("posts.content.halo.run/fake-post");
+    }
+
+    @Test
+    void testNameOf() {
+        String s = MeterUtils.nameOf("content.halo.run", "posts", "fake-post");
+        assertThat(s).isEqualTo("posts.content.halo.run/fake-post");
+    }
+
+    @Test
+    void visitCounter() {
+        MeterRegistry meterRegistry = new SimpleMeterRegistry();
+        MeterUtils.visitCounter(meterRegistry, "posts.content.halo.run/fake-post")
+            .increment();
+        RequiredSearch requiredSearch = meterRegistry.get("posts.content.halo.run/fake-post");
+        assertThat(requiredSearch.counter().count()).isEqualTo(1);
+        Meter.Id id = requiredSearch.counter().getId();
+        assertThat(id.getTag(MeterUtils.SCENE)).isEqualTo(MeterUtils.VISIT_SCENE);
+        assertThat(id.getTag(MeterUtils.METRICS_COMMON_TAG.getKey()))
+            .isEqualTo(MeterUtils.METRICS_COMMON_TAG.getValue());
+    }
+
+    @Test
+    void upvoteCounter() {
+        MeterRegistry meterRegistry = new SimpleMeterRegistry();
+        MeterUtils.upvoteCounter(meterRegistry, "posts.content.halo.run/fake-post")
+            .increment(2);
+        RequiredSearch requiredSearch = meterRegistry.get("posts.content.halo.run/fake-post");
+        assertThat(requiredSearch.counter().count()).isEqualTo(2);
+        Meter.Id id = requiredSearch.counter().getId();
+        assertThat(id.getTag(MeterUtils.SCENE)).isEqualTo(MeterUtils.UPVOTE_SCENE);
+        assertThat(id.getTag(MeterUtils.METRICS_COMMON_TAG.getKey()))
+            .isEqualTo(MeterUtils.METRICS_COMMON_TAG.getValue());
+    }
+
+    @Test
+    void totalCommentCounter() {
+        MeterRegistry meterRegistry = new SimpleMeterRegistry();
+        MeterUtils.totalCommentCounter(meterRegistry, "content.halo.run.posts.fake-post")
+            .increment(3);
+        RequiredSearch requiredSearch = meterRegistry.get("content.halo.run.posts.fake-post");
+        assertThat(requiredSearch.counter().count()).isEqualTo(3);
+        Meter.Id id = requiredSearch.counter().getId();
+        assertThat(id.getTag(MeterUtils.SCENE)).isEqualTo(MeterUtils.TOTAL_COMMENT_SCENE);
+        assertThat(id.getTag(MeterUtils.METRICS_COMMON_TAG.getKey()))
+            .isEqualTo(MeterUtils.METRICS_COMMON_TAG.getValue());
+    }
+
+    @Test
+    void approvedCommentCounter() {
+        MeterRegistry meterRegistry = new SimpleMeterRegistry();
+        MeterUtils.approvedCommentCounter(meterRegistry, "posts.content.halo.run/fake-post")
+            .increment(2);
+        RequiredSearch requiredSearch = meterRegistry.get("posts.content.halo.run/fake-post");
+        assertThat(requiredSearch.counter().count()).isEqualTo(2);
+        Meter.Id id = requiredSearch.counter().getId();
+        assertThat(id.getTag(MeterUtils.SCENE)).isEqualTo(MeterUtils.APPROVED_COMMENT_SCENE);
+        assertThat(id.getTag(MeterUtils.METRICS_COMMON_TAG.getKey()))
+            .isEqualTo(MeterUtils.METRICS_COMMON_TAG.getValue());
+    }
+
+    @Test
+    void isVisitCounter() {
+        MeterRegistry meterRegistry = new SimpleMeterRegistry();
+        Counter visitCounter =
+            MeterUtils.visitCounter(meterRegistry, "posts.content.halo.run/fake-post");
+        assertThat(MeterUtils.isVisitCounter(visitCounter)).isTrue();
+    }
+
+    @Test
+    void isUpvoteCounter() {
+        MeterRegistry meterRegistry = new SimpleMeterRegistry();
+        Counter upvoteCounter =
+            MeterUtils.upvoteCounter(meterRegistry, "posts.content.halo.run/fake-post");
+        assertThat(MeterUtils.isUpvoteCounter(upvoteCounter)).isTrue();
+        assertThat(MeterUtils.isVisitCounter(upvoteCounter)).isFalse();
+    }
+
+    @Test
+    void isTotalCommentCounter() {
+        MeterRegistry meterRegistry = new SimpleMeterRegistry();
+        Counter totalCommentCounter =
+            MeterUtils.totalCommentCounter(meterRegistry, "posts.content.halo.run/fake-post");
+        assertThat(MeterUtils.isTotalCommentCounter(totalCommentCounter)).isTrue();
+        assertThat(MeterUtils.isVisitCounter(totalCommentCounter)).isFalse();
+    }
+
+    @Test
+    void isApprovedCommentCounter() {
+        MeterRegistry meterRegistry = new SimpleMeterRegistry();
+        Counter approvedCommentCounter =
+            MeterUtils.approvedCommentCounter(meterRegistry, "posts.content.halo.run/fake-post");
+        assertThat(MeterUtils.isApprovedCommentCounter(approvedCommentCounter)).isTrue();
+        assertThat(MeterUtils.isVisitCounter(approvedCommentCounter)).isFalse();
+    }
+}

src/test/java/run/halo/app/theme/finders/impl/PostFinderImplTest.java

@@ -7,9 +7,9 @@ import static org.mockito.Mockito.when;
 import java.time.Instant;
 import java.util.List;
 import java.util.Map;
-import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 import reactor.core.publisher.Mono;
@@ -47,14 +47,9 @@ class PostFinderImplTest {
     @Mock
     private ContributorFinder contributorFinder;
 
+    @InjectMocks
     private PostFinderImpl postFinder;
 
-    @BeforeEach
-    void setUp() {
-        postFinder = new PostFinderImpl(client, contentService, tagFinder, categoryFinder,
-            contributorFinder);
-    }
-
     @Test
     void content() {
         Post post = post(1);