Add topology HTTP endpoint

agent/consul/state/config_entry.go

@@ -434,7 +434,7 @@ func (s *Store) discoveryChainSources(ws memdb.WatchSet, tx ReadTxn, dc string,
 
 	// Only return the services that directly target the destination
 	seenSource := make(map[structs.ServiceName]bool)
-	for sn, _ := range seenLink {
+	for sn := range seenLink {
 		req := discoverychain.CompileRequest{
 			ServiceName:         sn.Name,
 			EvaluateInNamespace: sn.NamespaceOrDefault(),

agent/http_register.go

@@ -99,6 +99,7 @@ func init() {
 	registerEndpoint("/v1/internal/ui/services", []string{"GET"}, (*HTTPHandlers).UIServices)
 	registerEndpoint("/v1/internal/ui/gateway-services-nodes/", []string{"GET"}, (*HTTPHandlers).UIGatewayServicesNodes)
 	registerEndpoint("/v1/internal/ui/gateway-intentions/", []string{"GET"}, (*HTTPHandlers).UIGatewayIntentions)
+	registerEndpoint("/v1/internal/ui/service-topology/", []string{"GET"}, (*HTTPHandlers).UIServiceTopology)
 	registerEndpoint("/v1/internal/acl/authorize", []string{"POST"}, (*HTTPHandlers).ACLAuthorize)
 	registerEndpoint("/v1/kv/", []string{"GET", "PUT", "DELETE"}, (*HTTPHandlers).KVSEndpoint)
 	registerEndpoint("/v1/operator/raft/configuration", []string{"GET"}, (*HTTPHandlers).OperatorRaftConfiguration)

agent/ui_endpoint.go

@@ -16,30 +16,51 @@ import (
 // to extract this.
 const metaExternalSource = "external-source"
 
+// ServiceSummary is used to summarize a service
+type ServiceSummary struct {
+	Kind              structs.ServiceKind `json:",omitempty"`
+	Name              string
+	Datacenter        string
+	Tags              []string
+	Nodes             []string
+	ExternalSources   []string
+	externalSourceSet map[string]struct{} // internal to track uniqueness
+	checks            map[string]*structs.HealthCheck
+	InstanceCount     int
+	ChecksPassing     int
+	ChecksWarning     int
+	ChecksCritical    int
+	GatewayConfig     GatewayConfig
+
+	structs.EnterpriseMeta
+}
+
+func (s *ServiceSummary) LessThan(other *ServiceSummary) bool {
+	if s.EnterpriseMeta.LessThan(&other.EnterpriseMeta) {
+		return true
+	}
+	return s.Name < other.Name
+}
+
+type ServiceListingSummary struct {
+	ServiceSummary
+
+	ConnectedWithProxy   bool
+	ConnectedWithGateway bool
+}
+
 type GatewayConfig struct {
 	AssociatedServiceCount int      `json:",omitempty"`
 	Addresses              []string `json:",omitempty"`
+
 	// internal to track uniqueness
 	addressesSet map[string]struct{}
 }
 
-// ServiceSummary is used to summarize a service
-type ServiceSummary struct {
-	Kind                 structs.ServiceKind `json:",omitempty"`
-	Name                 string
-	Tags                 []string
-	Nodes                []string
-	InstanceCount        int
-	ChecksPassing        int
-	ChecksWarning        int
-	ChecksCritical       int
-	ExternalSources      []string
-	externalSourceSet    map[string]struct{} // internal to track uniqueness
-	GatewayConfig        GatewayConfig       `json:",omitempty"`
-	ConnectedWithProxy   bool
-	ConnectedWithGateway bool
-
-	structs.EnterpriseMeta
+type ServiceTopology struct {
+	Upstreams      []*ServiceSummary
+	Downstreams    []*ServiceSummary
+	FilteredByACLs bool
 }
 
 // UINodes is used to list the nodes in a given datacenter. We return a
@@ -163,9 +184,39 @@ RPC:
 		return nil, err
 	}
 
-	// Generate the summary
-	// TODO (gateways) (freddy) Have Internal.ServiceDump return ServiceDump instead. Need to add bexpr filtering for type.
-	return summarizeServices(out.Nodes.ToServiceDump(), out.Gateways, s.agent.config, args.Datacenter), nil
+	// Store the names of the gateways associated with each service
+	var (
+		serviceGateways   = make(map[structs.ServiceName][]structs.ServiceName)
+		numLinkedServices = make(map[structs.ServiceName]int)
+	)
+	for _, gs := range out.Gateways {
+		serviceGateways[gs.Service] = append(serviceGateways[gs.Service], gs.Gateway)
+		numLinkedServices[gs.Gateway] += 1
+	}
+
+	summaries, hasProxy := summarizeServices(out.Nodes.ToServiceDump(), nil, "")
+	sorted := prepSummaryOutput(summaries, false)
+
+	var result []*ServiceListingSummary
+	for _, svc := range sorted {
+		sum := ServiceListingSummary{ServiceSummary: *svc}
+
+		sn := structs.NewServiceName(svc.Name, &svc.EnterpriseMeta)
+		if hasProxy[sn] {
+			sum.ConnectedWithProxy = true
+		}
+
+		// Verify that at least one of the gateways linked by config entry has an instance registered in the catalog
+		for _, gw := range serviceGateways[sn] {
+			if s := summaries[gw]; s != nil && sum.InstanceCount > 0 {
+				sum.ConnectedWithGateway = true
+			}
+		}
+		sum.GatewayConfig.AssociatedServiceCount = numLinkedServices[sn]
+
+		result = append(result, &sum)
+	}
+	return result, nil
 }
 
 // UIGatewayServices is used to query all the nodes for services associated with a gateway along with their gateway config
@@ -200,17 +251,56 @@ RPC:
 		return nil, err
 	}
 
-	return summarizeServices(out.Dump, nil, s.agent.config, args.Datacenter), nil
+	summaries, _ := summarizeServices(out.Dump, s.agent.config, args.Datacenter)
+	return prepSummaryOutput(summaries, false), nil
 }
 
-// TODO (freddy): Refactor to split up for the two use cases
-func summarizeServices(dump structs.ServiceDump, gateways structs.GatewayServices, cfg *config.RuntimeConfig, dc string) []*ServiceSummary {
-	// Collect the summary information
-	var services []structs.ServiceName
-	summary := make(map[structs.ServiceName]*ServiceSummary)
+func (s *HTTPHandlers) UIServiceTopology(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
+	// Parse arguments
+	args := structs.ServiceSpecificRequest{}
+	if done := s.parse(resp, req, &args.Datacenter, &args.QueryOptions); done {
+		return nil, nil
+	}
+	if err := s.parseEntMeta(req, &args.EnterpriseMeta); err != nil {
+		return nil, err
+	}
 
-	linkedGateways := make(map[structs.ServiceName][]structs.ServiceName)
-	hasProxy := make(map[structs.ServiceName]bool)
+	args.ServiceName = strings.TrimPrefix(req.URL.Path, "/v1/internal/ui/service-topology/")
+	if args.ServiceName == "" {
+		resp.WriteHeader(http.StatusBadRequest)
+		fmt.Fprint(resp, "Missing service name")
+		return nil, nil
+	}
+
+	// Make the RPC request
+	var out structs.IndexedServiceTopology
+	defer setMeta(resp, &out.QueryMeta)
+RPC:
+	if err := s.agent.RPC("Internal.ServiceTopology", &args, &out); err != nil {
+		// Retry the request allowing stale data if no leader
+		if strings.Contains(err.Error(), structs.ErrNoLeader.Error()) && !args.AllowStale {
+			args.AllowStale = true
+			goto RPC
+		}
+		return nil, err
+	}
+
+	upstreams, _ := summarizeServices(out.ServiceTopology.Upstreams.ToServiceDump(), nil, "")
+	downstreams, _ := summarizeServices(out.ServiceTopology.Downstreams.ToServiceDump(), nil, "")
+
+	sum := ServiceTopology{
+		Upstreams:      prepSummaryOutput(upstreams, true),
+		Downstreams:    prepSummaryOutput(downstreams, true),
+		FilteredByACLs: out.FilteredByACLs,
+	}
+	return sum, nil
+}
+
+func summarizeServices(dump structs.ServiceDump, cfg *config.RuntimeConfig, dc string) (map[structs.ServiceName]*ServiceSummary, map[structs.ServiceName]bool) {
+	var (
+		summary  = make(map[structs.ServiceName]*ServiceSummary)
+		hasProxy = make(map[structs.ServiceName]bool)
+	)
 
 	getService := func(service structs.ServiceName) *ServiceSummary {
 		serv, ok := summary[service]
@@ -223,22 +313,12 @@ func summarizeServices(dump structs.ServiceDump, gateways structs.GatewayService
 				InstanceCount: 0,
 			}
 			summary[service] = serv
-			services = append(services, service)
 		}
 		return serv
 	}
 
-	// Collect the list of services linked to each gateway up front
-	// THis also allows tracking whether a service name is associated with a gateway
-	gsCount := make(map[structs.ServiceName]int)
-
-	for _, gs := range gateways {
-		gsCount[gs.Gateway] += 1
-		linkedGateways[gs.Service] = append(linkedGateways[gs.Service], gs.Gateway)
-	}
-
 	for _, csn := range dump {
-		if csn.GatewayService != nil {
+		if cfg != nil && csn.GatewayService != nil {
 			gwsvc := csn.GatewayService
 			sum := getService(gwsvc.Service)
 			modifySummaryForGatewayService(cfg, dc, sum, gwsvc)
@@ -248,15 +328,27 @@ func summarizeServices(dump structs.ServiceDump, gateways structs.GatewayService
 		if csn.Service == nil {
 			continue
 		}
-		sid := structs.NewServiceName(csn.Service.Service, &csn.Service.EnterpriseMeta)
-		sum := getService(sid)
+		sn := structs.NewServiceName(csn.Service.Service, &csn.Service.EnterpriseMeta)
+		sum := getService(sn)
 
 		svc := csn.Service
 		sum.Nodes = append(sum.Nodes, csn.Node.Node)
 		sum.Kind = svc.Kind
+		sum.Datacenter = csn.Node.Datacenter
 		sum.InstanceCount += 1
 		if svc.Kind == structs.ServiceKindConnectProxy {
-			hasProxy[structs.NewServiceName(svc.Proxy.DestinationServiceName, &svc.EnterpriseMeta)] = true
+			sn := structs.NewServiceName(svc.Proxy.DestinationServiceName, &svc.EnterpriseMeta)
+			hasProxy[sn] = true
+
+			destination := getService(sn)
+			for _, check := range csn.Checks {
+				cid := structs.NewCheckID(check.CheckID, &check.EnterpriseMeta)
+				uid := structs.UniqueID(csn.Node.Node, cid.String())
+				if destination.checks == nil {
+					destination.checks = make(map[string]*structs.HealthCheck)
+				}
+				destination.checks[uid] = check
+			}
 		}
 		for _, tag := range svc.Tags {
 			found := false
@@ -266,7 +358,6 @@ func summarizeServices(dump structs.ServiceDump, gateways structs.GatewayService
 					break
 				}
 			}
-
 			if !found {
 				sum.Tags = append(sum.Tags, tag)
 			}
@@ -288,7 +379,28 @@ func summarizeServices(dump structs.ServiceDump, gateways structs.GatewayService
 		}
 
 		for _, check := range csn.Checks {
-			switch check.Status {
+			cid := structs.NewCheckID(check.CheckID, &check.EnterpriseMeta)
+			uid := structs.UniqueID(csn.Node.Node, cid.String())
+			if sum.checks == nil {
+				sum.checks = make(map[string]*structs.HealthCheck)
+			}
+			sum.checks[uid] = check
+		}
+	}
+
+	return summary, hasProxy
+}
+
+func prepSummaryOutput(summaries map[structs.ServiceName]*ServiceSummary, excludeSidecars bool) []*ServiceSummary {
+	var resp []*ServiceSummary
+
+	// Collect and sort resp for display
+	for _, sum := range summaries {
+		sort.Strings(sum.Nodes)
+		sort.Strings(sum.Tags)
+
+		for _, chk := range sum.checks {
+			switch chk.Status {
 			case api.HealthPassing:
 				sum.ChecksPassing++
 			case api.HealthWarning:
@@ -297,34 +409,15 @@ func summarizeServices(dump structs.ServiceDump, gateways structs.GatewayService
 				sum.ChecksCritical++
 			}
 		}
-	}
-
-	// Return the services in sorted order
-	sort.Slice(services, func(i, j int) bool {
-		return services[i].LessThan(&services[j])
-	})
-
-	output := make([]*ServiceSummary, len(summary))
-	for idx, service := range services {
-		sum := summary[service]
-		if hasProxy[service] {
-			sum.ConnectedWithProxy = true
-		}
-
-		// Verify that at least one of the gateways linked by config entry has an instance registered in the catalog
-		for _, gw := range linkedGateways[service] {
-			if s := summary[gw]; s != nil && s.InstanceCount > 0 {
-				sum.ConnectedWithGateway = true
-			}
+		if excludeSidecars && sum.Kind != structs.ServiceKindTypical {
+			continue
 		}
-		sum.GatewayConfig.AssociatedServiceCount = gsCount[service]
-
-		// Sort the nodes and tags
-		sort.Strings(sum.Nodes)
-		sort.Strings(sum.Tags)
-		output[idx] = sum
+		resp = append(resp, sum)
 	}
-	return output
+	sort.Slice(resp, func(i, j int) bool {
+		return resp[i].LessThan(resp[j])
+	})
+	return resp
 }
 
 func modifySummaryForGatewayService(

agent/ui_endpoint_test.go

@@ -223,6 +223,7 @@ func TestUiServices(t *testing.T) {
 			Service: &structs.NodeService{
 				Kind:    structs.ServiceKindTypical,
 				Service: "api",
+				ID:      "api-1",
 				Tags:    []string{"tag1", "tag2"},
 			},
 			Checks: structs.HealthChecks{
@@ -230,18 +231,20 @@ func TestUiServices(t *testing.T) {
 					Node:        "foo",
 					Name:        "api svc check",
 					ServiceName: "api",
+					ServiceID:   "api-1",
 					Status:      api.HealthWarning,
 				},
 			},
 		},
-		// register web svc on node foo
+		// register api-proxy svc on node foo
 		{
 			Datacenter:     "dc1",
 			Node:           "foo",
 			SkipNodeUpdate: true,
 			Service: &structs.NodeService{
 				Kind:    structs.ServiceKindConnectProxy,
-				Service: "web",
+				Service: "api-proxy",
+				ID:      "api-proxy-1",
 				Tags:    []string{},
 				Meta:    map[string]string{metaExternalSource: "k8s"},
 				Port:    1234,
@@ -252,8 +255,9 @@ func TestUiServices(t *testing.T) {
 			Checks: structs.HealthChecks{
 				&structs.HealthCheck{
 					Node:        "foo",
-					Name:        "web svc check",
-					ServiceName: "web",
+					Name:        "api proxy listening",
+					ServiceName: "api-proxy",
+					ServiceID:   "api-proxy-1",
 					Status:      api.HealthPassing,
 				},
 			},
@@ -264,14 +268,12 @@ func TestUiServices(t *testing.T) {
 			Node:       "bar",
 			Address:    "127.0.0.2",
 			Service: &structs.NodeService{
-				Kind:    structs.ServiceKindConnectProxy,
+				Kind:    structs.ServiceKindTypical,
 				Service: "web",
+				ID:      "web-1",
 				Tags:    []string{},
 				Meta:    map[string]string{metaExternalSource: "k8s"},
 				Port:    1234,
-				Proxy: structs.ConnectProxyConfig{
-					DestinationServiceName: "api",
-				},
 			},
 			Checks: []*structs.HealthCheck{
 				{
@@ -279,6 +281,7 @@ func TestUiServices(t *testing.T) {
 					Name:        "web svc check",
 					Status:      api.HealthCritical,
 					ServiceName: "web",
+					ServiceID:   "web-1",
 				},
 			},
 		},
@@ -366,76 +369,107 @@ func TestUiServices(t *testing.T) {
 		assertIndex(t, resp)
 
 		// Should be 2 nodes, and all the empty lists should be non-nil
-		summary := obj.([]*ServiceSummary)
-		require.Len(t, summary, 5)
+		summary := obj.([]*ServiceListingSummary)
+		require.Len(t, summary, 6)
 
 		// internal accounting that users don't see can be blown away
 		for _, sum := range summary {
 			sum.externalSourceSet = nil
+			sum.checks = nil
 		}
 
-		expected := []*ServiceSummary{
+		expected := []*ServiceListingSummary{
 			{
-				Kind:                 structs.ServiceKindTypical,
-				Name:                 "api",
-				Tags:                 []string{"tag1", "tag2"},
-				Nodes:                []string{"foo"},
-				InstanceCount:        1,
-				ChecksPassing:        2,
-				ChecksWarning:        1,
-				ChecksCritical:       0,
+				ServiceSummary: ServiceSummary{
+					Kind:           structs.ServiceKindTypical,
+					Name:           "api",
+					Datacenter:     "dc1",
+					Tags:           []string{"tag1", "tag2"},
+					Nodes:          []string{"foo"},
+					InstanceCount:  1,
+					ChecksPassing:  2,
+					ChecksWarning:  1,
+					ChecksCritical: 0,
+					EnterpriseMeta: *structs.DefaultEnterpriseMeta(),
+				},
 				ConnectedWithProxy:   true,
 				ConnectedWithGateway: true,
-				EnterpriseMeta:       *structs.DefaultEnterpriseMeta(),
 			},
 			{
-				Kind:                 structs.ServiceKindTypical,
-				Name:                 "cache",
-				Tags:                 nil,
-				Nodes:                []string{"zip"},
-				InstanceCount:        1,
-				ChecksPassing:        0,
-				ChecksWarning:        0,
-				ChecksCritical:       0,
+				ServiceSummary: ServiceSummary{
+					Kind:            structs.ServiceKindConnectProxy,
+					Name:            "api-proxy",
+					Datacenter:      "dc1",
+					Tags:            nil,
+					Nodes:           []string{"foo"},
+					InstanceCount:   1,
+					ChecksPassing:   2,
+					ChecksWarning:   0,
+					ChecksCritical:  0,
+					ExternalSources: []string{"k8s"},
+					EnterpriseMeta:  *structs.DefaultEnterpriseMeta(),
+				},
+			},
+			{
+				ServiceSummary: ServiceSummary{
+					Kind:           structs.ServiceKindTypical,
+					Name:           "cache",
+					Datacenter:     "dc1",
+					Tags:           nil,
+					Nodes:          []string{"zip"},
+					InstanceCount:  1,
+					ChecksPassing:  0,
+					ChecksWarning:  0,
+					ChecksCritical: 0,
+					EnterpriseMeta: *structs.DefaultEnterpriseMeta(),
+				},
 				ConnectedWithGateway: true,
-				EnterpriseMeta:       *structs.DefaultEnterpriseMeta(),
 			},
 			{
-				Kind:            structs.ServiceKindConnectProxy,
-				Name:            "web",
-				Tags:            nil,
-				Nodes:           []string{"bar", "foo"},
-				InstanceCount:   2,
-				ChecksPassing:   2,
-				ChecksWarning:   1,
-				ChecksCritical:  1,
-				ExternalSources: []string{"k8s"},
-				EnterpriseMeta:  *structs.DefaultEnterpriseMeta(),
+				ServiceSummary: ServiceSummary{
+					Kind:           structs.ServiceKindTypical,
+					Name:           "consul",
+					Datacenter:     "dc1",
+					Tags:           nil,
+					Nodes:          []string{a.Config.NodeName},
+					InstanceCount:  1,
+					ChecksPassing:  1,
+					ChecksWarning:  0,
+					ChecksCritical: 0,
+					EnterpriseMeta: *structs.DefaultEnterpriseMeta(),
+				},
 			},
 			{
-				Kind:           structs.ServiceKindTypical,
-				Name:           "consul",
-				Tags:           nil,
-				Nodes:          []string{a.Config.NodeName},
-				InstanceCount:  1,
-				ChecksPassing:  1,
-				ChecksWarning:  0,
-				ChecksCritical: 0,
-				EnterpriseMeta: *structs.DefaultEnterpriseMeta(),
+				ServiceSummary: ServiceSummary{
+					Kind:           structs.ServiceKindTerminatingGateway,
+					Name:           "terminating-gateway",
+					Datacenter:     "dc1",
+					Tags:           nil,
+					Nodes:          []string{"foo"},
+					InstanceCount:  1,
+					ChecksPassing:  1,
+					ChecksWarning:  0,
+					ChecksCritical: 0,
+					GatewayConfig:  GatewayConfig{AssociatedServiceCount: 2},
+					EnterpriseMeta: *structs.DefaultEnterpriseMeta(),
+				},
 			},
 			{
-				Kind:           structs.ServiceKindTerminatingGateway,
-				Name:           "terminating-gateway",
-				Tags:           nil,
-				Nodes:          []string{"foo"},
-				InstanceCount:  1,
-				ChecksPassing:  2,
-				ChecksWarning:  1,
-				GatewayConfig:  GatewayConfig{AssociatedServiceCount: 2},
-				EnterpriseMeta: *structs.DefaultEnterpriseMeta(),
+				ServiceSummary: ServiceSummary{
+					Kind:            structs.ServiceKindTypical,
+					Name:            "web",
+					Datacenter:      "dc1",
+					Tags:            nil,
+					Nodes:           []string{"bar"},
+					InstanceCount:   1,
+					ChecksPassing:   0,
+					ChecksWarning:   0,
+					ChecksCritical:  1,
+					ExternalSources: []string{"k8s"},
+					EnterpriseMeta:  *structs.DefaultEnterpriseMeta(),
+				},
 			},
 		}
-
 		require.ElementsMatch(t, expected, summary)
 	})
 
@@ -448,39 +482,46 @@ func TestUiServices(t *testing.T) {
 		assertIndex(t, resp)
 
 		// Should be 2 nodes, and all the empty lists should be non-nil
-		summary := obj.([]*ServiceSummary)
+		summary := obj.([]*ServiceListingSummary)
 		require.Len(t, summary, 2)
 
 		// internal accounting that users don't see can be blown away
 		for _, sum := range summary {
 			sum.externalSourceSet = nil
+			sum.checks = nil
 		}
 
-		expected := []*ServiceSummary{
+		expected := []*ServiceListingSummary{
 			{
-				Kind:                 structs.ServiceKindTypical,
-				Name:                 "api",
-				Tags:                 []string{"tag1", "tag2"},
-				Nodes:                []string{"foo"},
-				InstanceCount:        1,
-				ChecksPassing:        2,
-				ChecksWarning:        1,
-				ChecksCritical:       0,
-				ConnectedWithProxy:   true,
+				ServiceSummary: ServiceSummary{
+					Kind:           structs.ServiceKindTypical,
+					Name:           "api",
+					Datacenter:     "dc1",
+					Tags:           []string{"tag1", "tag2"},
+					Nodes:          []string{"foo"},
+					InstanceCount:  1,
+					ChecksPassing:  1,
+					ChecksWarning:  1,
+					ChecksCritical: 0,
+					EnterpriseMeta: *structs.DefaultEnterpriseMeta(),
+				},
+				ConnectedWithProxy:   false,
 				ConnectedWithGateway: false,
-				EnterpriseMeta:       *structs.DefaultEnterpriseMeta(),
 			},
 			{
-				Kind:            structs.ServiceKindConnectProxy,
-				Name:            "web",
-				Tags:            nil,
-				Nodes:           []string{"bar", "foo"},
-				InstanceCount:   2,
-				ChecksPassing:   2,
-				ChecksWarning:   1,
-				ChecksCritical:  1,
-				ExternalSources: []string{"k8s"},
-				EnterpriseMeta:  *structs.DefaultEnterpriseMeta(),
+				ServiceSummary: ServiceSummary{
+					Kind:            structs.ServiceKindTypical,
+					Name:            "web",
+					Datacenter:      "dc1",
+					Tags:            nil,
+					Nodes:           []string{"bar"},
+					InstanceCount:   1,
+					ChecksPassing:   0,
+					ChecksWarning:   0,
+					ChecksCritical:  1,
+					ExternalSources: []string{"k8s"},
+					EnterpriseMeta:  *structs.DefaultEnterpriseMeta(),
+				},
 			},
 		}
 		require.ElementsMatch(t, expected, summary)
@@ -582,7 +623,14 @@ func TestUIGatewayServiceNodes_Terminating(t *testing.T) {
 	assert.Nil(t, err)
 	assertIndex(t, resp)
 
-	dump := obj.([]*ServiceSummary)
+	summary := obj.([]*ServiceSummary)
+
+	// internal accounting that users don't see can be blown away
+	for _, sum := range summary {
+		sum.externalSourceSet = nil
+		sum.checks = nil
+	}
+
 	expect := []*ServiceSummary{
 		{
 			Name:           "redis",
@@ -590,6 +638,7 @@ func TestUIGatewayServiceNodes_Terminating(t *testing.T) {
 		},
 		{
 			Name:           "db",
+			Datacenter:     "dc1",
 			Tags:           []string{"backup", "primary"},
 			Nodes:          []string{"bar", "baz"},
 			InstanceCount:  2,
@@ -599,7 +648,7 @@ func TestUIGatewayServiceNodes_Terminating(t *testing.T) {
 			EnterpriseMeta: *structs.DefaultEnterpriseMeta(),
 		},
 	}
-	assert.ElementsMatch(t, expect, dump)
+	assert.ElementsMatch(t, expect, summary)
 }
 
 func TestUIGatewayServiceNodes_Ingress(t *testing.T) {
@@ -748,6 +797,7 @@ func TestUIGatewayServiceNodes_Ingress(t *testing.T) {
 		},
 		{
 			Name:           "db",
+			Datacenter:     "dc1",
 			Tags:           []string{"backup", "primary"},
 			Nodes:          []string{"bar", "baz"},
 			InstanceCount:  2,
@@ -767,6 +817,7 @@ func TestUIGatewayServiceNodes_Ingress(t *testing.T) {
 	// internal accounting that users don't see can be blown away
 	for _, sum := range dump {
 		sum.GatewayConfig.addressesSet = nil
+		sum.checks = nil
 	}
 	assert.ElementsMatch(t, expect, dump)
 }
@@ -878,3 +929,386 @@ func TestUIEndpoint_modifySummaryForGatewayService_UseRequestedDCInsteadOfConfig
 	expected := serviceCanonicalDNSName("test", "ingress", "dc2", "consul", nil) + ":42"
 	require.Equal(t, expected, sum.GatewayConfig.Addresses[0])
 }
+
+func TestUIServiceTopology(t *testing.T) {
+	t.Parallel()
+
+	a := NewTestAgent(t, "")
+	defer a.Shutdown()
+
+	// Register terminating gateway and config entry linking it to postgres + redis
+	{
+		registrations := map[string]*structs.RegisterRequest{
+			"Node foo": {
+				Datacenter: "dc1",
+				Node:       "foo",
+				Address:    "127.0.0.2",
+				Checks: structs.HealthChecks{
+					&structs.HealthCheck{
+						Node:    "foo",
+						CheckID: "foo:alive",
+						Name:    "foo-liveness",
+						Status:  api.HealthPassing,
+					},
+				},
+			},
+			"Service api on foo": {
+				Datacenter:     "dc1",
+				Node:           "foo",
+				SkipNodeUpdate: true,
+				Service: &structs.NodeService{
+					Kind:    structs.ServiceKindTypical,
+					ID:      "api",
+					Service: "api",
+					Port:    9090,
+					Address: "198.18.1.2",
+				},
+				Checks: structs.HealthChecks{
+					&structs.HealthCheck{
+						Node:        "foo",
+						CheckID:     "foo:api",
+						Name:        "api-liveness",
+						Status:      api.HealthPassing,
+						ServiceID:   "api",
+						ServiceName: "api",
+					},
+				},
+			},
+			"Service api-proxy": {
+				Datacenter:     "dc1",
+				Node:           "foo",
+				SkipNodeUpdate: true,
+				Service: &structs.NodeService{
+					Kind:    structs.ServiceKindConnectProxy,
+					ID:      "api-proxy",
+					Service: "api-proxy",
+					Port:    8443,
+					Address: "198.18.1.2",
+					Proxy: structs.ConnectProxyConfig{
+						DestinationServiceName: "api",
+						Upstreams: structs.Upstreams{
+							{
+								DestinationName: "web",
+								LocalBindPort:   8080,
+							},
+						},
+					},
+				},
+				Checks: structs.HealthChecks{
+					&structs.HealthCheck{
+						Node:        "foo",
+						CheckID:     "foo:api-proxy",
+						Name:        "api proxy listening",
+						Status:      api.HealthPassing,
+						ServiceID:   "api-proxy",
+						ServiceName: "api-proxy",
+					},
+				},
+			},
+			"Node bar": {
+				Datacenter: "dc1",
+				Node:       "bar",
+				Address:    "127.0.0.3",
+				Checks: structs.HealthChecks{
+					&structs.HealthCheck{
+						Node:    "bar",
+						CheckID: "bar:alive",
+						Name:    "bar-liveness",
+						Status:  api.HealthPassing,
+					},
+				},
+			},
+			"Service web on bar": {
+				Datacenter:     "dc1",
+				Node:           "bar",
+				SkipNodeUpdate: true,
+				Service: &structs.NodeService{
+					Kind:    structs.ServiceKindTypical,
+					ID:      "web",
+					Service: "web",
+					Port:    80,
+					Address: "198.18.1.20",
+				},
+				Checks: structs.HealthChecks{
+					&structs.HealthCheck{
+						Node:        "bar",
+						CheckID:     "bar:web",
+						Name:        "web-liveness",
+						Status:      api.HealthWarning,
+						ServiceID:   "web",
+						ServiceName: "web",
+					},
+				},
+			},
+			"Service web-proxy on bar": {
+				Datacenter:     "dc1",
+				Node:           "bar",
+				SkipNodeUpdate: true,
+				Service: &structs.NodeService{
+					Kind:    structs.ServiceKindConnectProxy,
+					ID:      "web-proxy",
+					Service: "web-proxy",
+					Port:    8443,
+					Address: "198.18.1.20",
+					Proxy: structs.ConnectProxyConfig{
+						DestinationServiceName: "web",
+						Upstreams: structs.Upstreams{
+							{
+								DestinationName: "redis",
+								LocalBindPort:   123,
+							},
+						},
+					},
+				},
+				Checks: structs.HealthChecks{
+					&structs.HealthCheck{
+						Node:        "bar",
+						CheckID:     "bar:web-proxy",
+						Name:        "web proxy listening",
+						Status:      api.HealthCritical,
+						ServiceID:   "web-proxy",
+						ServiceName: "web-proxy",
+					},
+				},
+			},
+			"Node baz": {
+				Datacenter: "dc1",
+				Node:       "baz",
+				Address:    "127.0.0.4",
+				Checks: structs.HealthChecks{
+					&structs.HealthCheck{
+						Node:    "baz",
+						CheckID: "baz:alive",
+						Name:    "baz-liveness",
+						Status:  api.HealthPassing,
+					},
+				},
+			},
+			"Service web on baz": {
+				Datacenter:     "dc1",
+				Node:           "baz",
+				SkipNodeUpdate: true,
+				Service: &structs.NodeService{
+					Kind:    structs.ServiceKindTypical,
+					ID:      "web",
+					Service: "web",
+					Port:    80,
+					Address: "198.18.1.40",
+				},
+				Checks: structs.HealthChecks{
+					&structs.HealthCheck{
+						Node:        "baz",
+						CheckID:     "baz:web",
+						Name:        "web-liveness",
+						Status:      api.HealthPassing,
+						ServiceID:   "web",
+						ServiceName: "web",
+					},
+				},
+			},
+			"Service web-proxy on baz": {
+				Datacenter:     "dc1",
+				Node:           "baz",
+				SkipNodeUpdate: true,
+				Service: &structs.NodeService{
+					Kind:    structs.ServiceKindConnectProxy,
+					ID:      "web-proxy",
+					Service: "web-proxy",
+					Port:    8443,
+					Address: "198.18.1.40",
+					Proxy: structs.ConnectProxyConfig{
+						DestinationServiceName: "web",
+						Upstreams: structs.Upstreams{
+							{
+								DestinationName: "redis",
+								LocalBindPort:   123,
+							},
+						},
+					},
+				},
+				Checks: structs.HealthChecks{
+					&structs.HealthCheck{
+						Node:        "baz",
+						CheckID:     "baz:web-proxy",
+						Name:        "web proxy listening",
+						Status:      api.HealthCritical,
+						ServiceID:   "web-proxy",
+						ServiceName: "web-proxy",
+					},
+				},
+			},
+			"Node zip": {
+				Datacenter: "dc1",
+				Node:       "zip",
+				Address:    "127.0.0.5",
+				Checks: structs.HealthChecks{
+					&structs.HealthCheck{
+						Node:    "zip",
+						CheckID: "zip:alive",
+						Name:    "zip-liveness",
+						Status:  api.HealthPassing,
+					},
+				},
+			},
+			"Service redis on zip": {
+				Datacenter:     "dc1",
+				Node:           "zip",
+				SkipNodeUpdate: true,
+				Service: &structs.NodeService{
+					Kind:    structs.ServiceKindTypical,
+					ID:      "redis",
+					Service: "redis",
+					Port:    6379,
+					Address: "198.18.1.60",
+				},
+				Checks: structs.HealthChecks{
+					&structs.HealthCheck{
+						Node:        "zip",
+						CheckID:     "zip:redis",
+						Name:        "redis-liveness",
+						Status:      api.HealthPassing,
+						ServiceID:   "redis",
+						ServiceName: "redis",
+					},
+				},
+			},
+			"Service redis-proxy on zip": {
+				Datacenter:     "dc1",
+				Node:           "zip",
+				SkipNodeUpdate: true,
+				Service: &structs.NodeService{
+					Kind:    structs.ServiceKindConnectProxy,
+					ID:      "redis-proxy",
+					Service: "redis-proxy",
+					Port:    8443,
+					Address: "198.18.1.60",
+					Proxy: structs.ConnectProxyConfig{
+						DestinationServiceName: "redis",
+					},
+				},
+				Checks: structs.HealthChecks{
+					&structs.HealthCheck{
+						Node:        "zip",
+						CheckID:     "zip:redis-proxy",
+						Name:        "redis proxy listening",
+						Status:      api.HealthCritical,
+						ServiceID:   "redis-proxy",
+						ServiceName: "redis-proxy",
+					},
+				},
+			},
+		}
+		for _, args := range registrations {
+			var out struct{}
+			require.NoError(t, a.RPC("Catalog.Register", args, &out))
+		}
+	}
+
+	t.Run("api", func(t *testing.T) {
+		// Request topology for api
+		req, _ := http.NewRequest("GET", "/v1/internal/ui/service-topology/api", nil)
+		resp := httptest.NewRecorder()
+		obj, err := a.srv.UIServiceTopology(resp, req)
+		assert.Nil(t, err)
+		assertIndex(t, resp)
+
+		expect := ServiceTopology{
+			Upstreams: []*ServiceSummary{
+				{
+					Name:           "web",
+					Datacenter:     "dc1",
+					Nodes:          []string{"bar", "baz"},
+					InstanceCount:  2,
+					ChecksPassing:  3,
+					ChecksWarning:  1,
+					ChecksCritical: 2,
+				},
+			},
+			FilteredByACLs: false,
+		}
+		result := obj.(ServiceTopology)
+
+		// Internal accounting that is not returned in JSON response
+		for _, u := range result.Upstreams {
+			u.externalSourceSet = nil
+			u.checks = nil
+		}
+		require.Equal(t, expect, result)
+	})
+
+	t.Run("web", func(t *testing.T) {
+		// Request topology for web
+		req, _ := http.NewRequest("GET", "/v1/internal/ui/service-topology/web", nil)
+		resp := httptest.NewRecorder()
+		obj, err := a.srv.UIServiceTopology(resp, req)
+		assert.Nil(t, err)
+		assertIndex(t, resp)
+
+		expect := ServiceTopology{
+			Upstreams: []*ServiceSummary{
+				{
+					Name:           "redis",
+					Datacenter:     "dc1",
+					Nodes:          []string{"zip"},
+					InstanceCount:  1,
+					ChecksPassing:  2,
+					ChecksCritical: 1,
+				},
+			},
+			Downstreams: []*ServiceSummary{
+				{
+					Name:          "api",
+					Datacenter:    "dc1",
+					Nodes:         []string{"foo"},
+					InstanceCount: 1,
+					ChecksPassing: 3,
+				},
+			},
+			FilteredByACLs: false,
+		}
+		result := obj.(ServiceTopology)
+
+		// Internal accounting that is not returned in JSON response
+		for _, u := range result.Upstreams {
+			u.externalSourceSet = nil
+			u.checks = nil
+		}
+		for _, d := range result.Downstreams {
+			d.externalSourceSet = nil
+			d.checks = nil
+		}
+		require.Equal(t, expect, result)
+	})
+
+	t.Run("redis", func(t *testing.T) {
+		// Request topology for redis
+		req, _ := http.NewRequest("GET", "/v1/internal/ui/service-topology/redis", nil)
+		resp := httptest.NewRecorder()
+		obj, err := a.srv.UIServiceTopology(resp, req)
+		assert.Nil(t, err)
+		assertIndex(t, resp)
+
+		expect := ServiceTopology{
+			Downstreams: []*ServiceSummary{
+				{
+					Name:           "web",
+					Datacenter:     "dc1",
+					Nodes:          []string{"bar", "baz"},
+					InstanceCount:  2,
+					ChecksPassing:  3,
+					ChecksWarning:  1,
+					ChecksCritical: 2,
+				},
+			},
+			FilteredByACLs: false,
+		}
+		result := obj.(ServiceTopology)
+
+		// Internal accounting that is not returned in JSON response
+		for _, d := range result.Downstreams {
+			d.externalSourceSet = nil
+			d.checks = nil
+		}
+		require.Equal(t, expect, result)
+	})
+}