web: simplify prefix handling using util/route package.

util/route/route.go

@@ -60,8 +60,7 @@ func New() *Router {
 	return &Router{rtr: httprouter.New()}
 }
 
-// WithPrefix returns a router that prefixes all registered routes
-// with preifx.
+// WithPrefix returns a router that prefixes all registered routes with prefix.
 func (r *Router) WithPrefix(prefix string) *Router {
 	return &Router{rtr: r.rtr, prefix: r.prefix + prefix}
 }

web/api/api.go

@@ -23,6 +23,7 @@ import (
 	"github.com/prometheus/prometheus/promql"
 	"github.com/prometheus/prometheus/storage/local"
 	"github.com/prometheus/prometheus/util/httputil"
+	"github.com/prometheus/prometheus/util/route"
 )
 
 // MetricsService manages the /api HTTP endpoint.
@@ -33,19 +34,15 @@ type MetricsService struct {
 }
 
 // RegisterHandler registers the handler for the various endpoints below /api.
-func (msrv *MetricsService) RegisterHandler(mux *http.ServeMux, pathPrefix string) {
-	handler := func(h func(http.ResponseWriter, *http.Request)) http.Handler {
-		return httputil.CompressionHandler{
-			Handler: http.HandlerFunc(h),
-		}
+func (msrv *MetricsService) RegisterHandler(router *route.Router) {
+	router.Get("/query", handle("query", msrv.Query))
+	router.Get("/query_range", handle("query_range", msrv.QueryRange))
+	router.Get("/metrics", handle("metrics", msrv.Metrics))
+}
+
+func handle(name string, f http.HandlerFunc) http.HandlerFunc {
+	h := httputil.CompressionHandler{
+		Handler: f,
 	}
-	mux.Handle(pathPrefix+"/api/query", prometheus.InstrumentHandler(
-		pathPrefix+"/api/query", handler(msrv.Query),
-	))
-	mux.Handle(pathPrefix+"/api/query_range", prometheus.InstrumentHandler(
-		pathPrefix+"/api/query_range", handler(msrv.QueryRange),
-	))
-	mux.Handle(pathPrefix+"/api/metrics", prometheus.InstrumentHandler(
-		pathPrefix+"/api/metrics", handler(msrv.Metrics),
-	))
+	return prometheus.InstrumentHandler(name, h)
 }

web/api/api_test.go

@@ -25,6 +25,7 @@ import (
 
 	"github.com/prometheus/prometheus/promql"
 	"github.com/prometheus/prometheus/storage/local"
+	"github.com/prometheus/prometheus/util/route"
 )
 
 // This is a bit annoying. On one hand, we have to choose a current timestamp
@@ -97,9 +98,10 @@ func TestQuery(t *testing.T) {
 		Storage:     storage,
 		QueryEngine: promql.NewEngine(storage),
 	}
-	api.RegisterHandler(http.DefaultServeMux, "")
+	rtr := route.New()
+	api.RegisterHandler(rtr.WithPrefix("/api"))
 
-	server := httptest.NewServer(http.DefaultServeMux)
+	server := httptest.NewServer(rtr)
 	defer server.Close()
 
 	for i, s := range scenarios {

web/blob/blob.go

@@ -9,6 +9,8 @@ import (
 	"strings"
 
 	"github.com/prometheus/log"
+
+	"github.com/prometheus/prometheus/util/route"
 )
 
 // Sub-directories for templates and static content.
@@ -46,7 +48,9 @@ func GetFile(bucket string, name string) ([]byte, error) {
 type Handler struct{}
 
 func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	name := r.URL.Path
+	ctx := route.Context(r)
+
+	name := strings.Trim(route.Param(ctx, "filepath"), "/")
 	if name == "" {
 		name = "index.html"
 	}

web/consoles.go

@@ -22,8 +22,10 @@ import (
 	"path/filepath"
 
 	clientmodel "github.com/prometheus/client_golang/model"
+
 	"github.com/prometheus/prometheus/promql"
 	"github.com/prometheus/prometheus/template"
+	"github.com/prometheus/prometheus/util/route"
 )
 
 var (
@@ -38,7 +40,10 @@ type ConsolesHandler struct {
 }
 
 func (h *ConsolesHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	file, err := http.Dir(*consoleTemplatesPath).Open(r.URL.Path)
+	ctx := route.Context(r)
+	name := route.Param(ctx, "filepath")
+
+	file, err := http.Dir(*consoleTemplatesPath).Open(name)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusNotFound)
 		return
@@ -67,10 +72,10 @@ func (h *ConsolesHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}{
 		RawParams: rawParams,
 		Params:    params,
-		Path:      r.URL.Path,
+		Path:      name,
 	}
 
-	tmpl := template.NewTemplateExpander(string(text), "__console_"+r.URL.Path, data, clientmodel.Now(), h.QueryEngine, h.PathPrefix)
+	tmpl := template.NewTemplateExpander(string(text), "__console_"+name, data, clientmodel.Now(), h.QueryEngine, h.PathPrefix)
 	filenames, err := filepath.Glob(*consoleLibrariesPath + "/*.lib")
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)

web/web.go

@@ -28,6 +28,7 @@ import (
 
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/log"
+	"github.com/prometheus/prometheus/util/route"
 
 	clientmodel "github.com/prometheus/client_golang/model"
 
@@ -50,7 +51,7 @@ var (
 // WebService handles the HTTP endpoints with the exception of /api.
 type WebService struct {
 	QuitChan chan struct{}
-	mux      *http.ServeMux
+	router   *route.Router
 }
 
 type WebServiceOptions struct {
@@ -64,61 +65,46 @@ type WebServiceOptions struct {
 
 // NewWebService returns a new WebService.
 func NewWebService(o *WebServiceOptions) *WebService {
-	mux := http.NewServeMux()
+	router := route.New()
 
 	ws := &WebService{
-		mux:      mux,
+		router:   router,
 		QuitChan: make(chan struct{}),
 	}
 
-	mux.HandleFunc("/", prometheus.InstrumentHandlerFunc(o.PathPrefix, func(rw http.ResponseWriter, req *http.Request) {
-		// The "/" pattern matches everything, so we need to check
-		// that we're at the root here.
-		if req.URL.Path == o.PathPrefix+"/" {
-			o.StatusHandler.ServeHTTP(rw, req)
-		} else if req.URL.Path == o.PathPrefix {
-			http.Redirect(rw, req, o.PathPrefix+"/", http.StatusFound)
-		} else if !strings.HasPrefix(req.URL.Path, o.PathPrefix+"/") {
-			// We're running under a prefix but the user requested something
-			// outside of it. Let's see if this page exists under the prefix.
-			http.Redirect(rw, req, o.PathPrefix+req.URL.Path, http.StatusFound)
-		} else {
-			http.NotFound(rw, req)
-		}
-	}))
-	mux.Handle(o.PathPrefix+"/alerts", prometheus.InstrumentHandler(
-		o.PathPrefix+"/alerts", o.AlertsHandler,
-	))
-	mux.Handle(o.PathPrefix+"/consoles/", prometheus.InstrumentHandler(
-		o.PathPrefix+"/consoles/", http.StripPrefix(o.PathPrefix+"/consoles/", o.ConsolesHandler),
-	))
-	mux.Handle(o.PathPrefix+"/graph", prometheus.InstrumentHandler(
-		o.PathPrefix+"/graph", o.GraphsHandler,
-	))
-	mux.Handle(o.PathPrefix+"/heap", prometheus.InstrumentHandler(
-		o.PathPrefix+"/heap", http.HandlerFunc(dumpHeap),
-	))
-
-	o.MetricsHandler.RegisterHandler(mux, o.PathPrefix)
-	mux.Handle(o.PathPrefix+*metricsPath, prometheus.Handler())
+	if o.PathPrefix != "" {
+		// If the prefix is missing for the root path, append it.
+		router.Get("/", func(w http.ResponseWriter, r *http.Request) {
+			http.Redirect(w, r, o.PathPrefix, 301)
+		})
+		router = router.WithPrefix(o.PathPrefix)
+	}
+
+	instr := prometheus.InstrumentHandler
+
+	router.Get("/", instr("status", o.StatusHandler))
+	router.Get("/alerts", instr("alerts", o.AlertsHandler))
+	router.Get("/graph", instr("graph", o.GraphsHandler))
+	router.Get("/heap", instr("heap", http.HandlerFunc(dumpHeap)))
+
+	router.Get(*metricsPath, prometheus.Handler().ServeHTTP)
+
+	o.MetricsHandler.RegisterHandler(router.WithPrefix("/api"))
+
+	router.Get("/consoles/*filepath", instr("consoles", o.ConsolesHandler))
+
 	if *useLocalAssets {
-		mux.Handle(o.PathPrefix+"/static/", prometheus.InstrumentHandler(
-			o.PathPrefix+"/static/", http.StripPrefix(o.PathPrefix+"/static/", http.FileServer(http.Dir("web/static"))),
-		))
+		router.Get("/static/*filepath", instr("static", route.FileServe("web/static")))
 	} else {
-		mux.Handle(o.PathPrefix+"/static/", prometheus.InstrumentHandler(
-			o.PathPrefix+"/static/", http.StripPrefix(o.PathPrefix+"/static/", new(blob.Handler)),
-		))
+		router.Get("/static/*filepath", instr("static", blob.Handler{}))
 	}
 
 	if *userAssetsPath != "" {
-		mux.Handle(o.PathPrefix+"/user/", prometheus.InstrumentHandler(
-			o.PathPrefix+"/user/", http.StripPrefix(o.PathPrefix+"/user/", http.FileServer(http.Dir(*userAssetsPath))),
-		))
+		router.Get("/user/*filepath", instr("user", route.FileServe(*userAssetsPath)))
 	}
 
 	if *enableQuit {
-		mux.Handle(o.PathPrefix+"/-/quit", http.HandlerFunc(ws.quitHandler))
+		router.Post("/-/quit", ws.quitHandler)
 	}
 
 	return ws
@@ -130,7 +116,7 @@ func (ws *WebService) Run() {
 
 	// If we cannot bind to a port, retry after 30 seconds.
 	for {
-		err := http.ListenAndServe(*listenAddress, ws.mux)
+		err := http.ListenAndServe(*listenAddress, ws.router)
 		if err != nil {
 			log.Errorf("Could not listen on %s: %s", *listenAddress, err)
 		}
@@ -139,12 +125,6 @@ func (ws *WebService) Run() {
 }
 
 func (ws *WebService) quitHandler(w http.ResponseWriter, r *http.Request) {
-	if r.Method != "POST" {
-		w.Header().Add("Allow", "POST")
-		w.WriteHeader(http.StatusMethodNotAllowed)
-		return
-	}
-
 	fmt.Fprintf(w, "Requesting termination... Goodbye!")
 
 	close(ws.QuitChan)