retrieval/scrape.go

@@ -124,8 +124,9 @@ type scrapePool struct {
 	client *http.Client
 	// Targets and loops must always be synchronized to have the same
 	// set of hashes.
-	targets map[uint64]*Target
-	loops   map[uint64]loop
+	targets        map[uint64]*Target
+	droppedTargets []*Target
+	loops          map[uint64]loop
 	// Constructor for new scrape loops. This is settable for testing convenience.
 	newLoop func(*Target, scraper) loop
@@ -251,7 +252,13 @@ func (sp *scrapePool) Sync(tgs []*config.TargetGroup) {
 			level.Error(sp.logger).Log("msg", "creating targets failed", "err", err)
 			continue
 		}
-		all = append(all, targets...)
+		for _, t := range targets {
+			if t.Labels().Len() > 0 {
+				all = append(all, t)
+			} else if t.DiscoveredLabels().Len() > 0 {
+				sp.droppedTargets = append(sp.droppedTargets, t)
+			}
+		}
 	}
 	sp.sync(all)

retrieval/target.go

@@ -251,7 +251,7 @@ func (app *timeLimitAppender) AddFast(lset labels.Labels, ref uint64, t int64, v
 // populateLabels builds a label set from the given label set and scrape configuration.
 // It returns a label set before relabeling was applied as the second return value.
-// Returns a nil label set if the target is dropped during relabeling.
+// Returns the original discovered label set found before relabelling was applied if the target is dropped during relabeling.
 func populateLabels(lset labels.Labels, cfg *config.ScrapeConfig) (res, orig labels.Labels, err error) {
 	// Copy labels into the labelset for the target if they are not set already.
 	scrapeLabels := []labels.Label{
@@ -278,7 +278,7 @@ func populateLabels(lset labels.Labels, cfg *config.ScrapeConfig) (res, orig lab
 	// Check if the target was dropped.
 	if lset == nil {
-		return nil, nil, nil
+		return nil, preRelabelLabels, nil
 	}
 	if v := lset.Get(model.AddressLabel); v == "" {
 		return nil, nil, fmt.Errorf("no address")
@@ -362,7 +362,7 @@ func targetsFromGroup(tg *config.TargetGroup, cfg *config.ScrapeConfig) ([]*Targ
 		if err != nil {
 			return nil, fmt.Errorf("instance %d in group %s: %s", i, tg, err)
 		}
-		if lbls != nil {
+		if lbls != nil || origLabels != nil {
 			targets = append(targets, NewTarget(lbls, origLabels, cfg.Params))
 		}
 	}

retrieval/targetmanager.go

@@ -143,6 +143,23 @@ func (tm *TargetManager) reload() {
 	}
 }
+// TargetMap returns map of active and dropped targets and their corresponding scrape config job name.
+func (tm *TargetManager) TargetMap() map[string][]*Target {
+	tm.mtx.RLock()
+	defer tm.mtx.RUnlock()
+
+	targetsMap := make(map[string][]*Target)
+	for jobName, ps := range tm.targetSets {
+		ps.sp.mtx.RLock()
+		for _, t := range ps.sp.targets {
+			targetsMap[jobName] = append(targetsMap[jobName], t)
+		}
+		targetsMap[jobName] = append(targetsMap[jobName], ps.sp.droppedTargets...)
+		ps.sp.mtx.RUnlock()
+	}
+	return targetsMap
+}
+
 // Targets returns the targets currently being scraped.
 func (tm *TargetManager) Targets() []*Target {
 	tm.mtx.RLock()

web/ui/templates/_base.html

@@ -49,6 +49,7 @@
                 <li><a href="{{ pathPrefix }}/config">Configuration</a></li>
                 <li><a href="{{ pathPrefix }}/rules">Rules</a></li>
                 <li><a href="{{ pathPrefix }}/targets">Targets</a></li>
+                <li><a href="{{ pathPrefix }}/service-discovery">Service Discovery</a></li>
               </ul>
             </li>
             <li>

web/ui/templates/service-discovery.html

+{{define "head"}}
+<link type="text/css" rel="stylesheet" href="{{ pathPrefix }}/static/css/targets.css?v={{ buildVersion }}">
+<script src="{{ pathPrefix }}/static/js/targets.js?v={{ buildVersion }}"></script>
+{{end}}
+
+<style>
+  *[id]:before {
+    display: block;
+    content: " ";
+    margin-top: -65px;
+    height: 65px;
+    visibility: hidden;
+  }
+</style>
+
+{{define "content"}}
+  <div class="container-fluid">
+
+    <h1>Service Discovery</h1>
+    <div class="table-container">
+      <table class="table table-condensed table-bordered table-striped table-hover">
+      <ul>
+        {{range $i, $job := .Index}}
+          <li>
+            <a href="#job-{{$job}}">{{$job}}</a>
+          </li>
+        {{end}}
+      </ul>
+    </div>
+
+    {{$targets := .Targets}}
+    {{range $job := .Index}}
+
+    <div class="table-container">
+      <h2 id="job-{{$job}}">
+        {{$job}}
+        <button type="button" class="targets collapsed-table btn btn-primary">show more</button>
+      </h2>
+      <table class="table table-condensed table-bordered table-striped table-hover" style="display:none">
+        <thead class="job_details">
+          <tr>
+            <th>Discovered Labels</th>
+            <th>Target Labels</th>
+          </tr>
+        </thead>
+        <tbody>
+
+        {{range index $targets $job}}
+          <tr>
+            <td class="labels">
+                {{$labels := .DiscoveredLabels.Map }}
+                <ul style="list-style-type:none">
+                  {{range $label, $value := $labels}}
+                    <li>
+                      <span class="label label-primary">{{$label}}="{{$value}}"</span>
+                    </li>
+                  {{else}}
+                  <li>
+                    <span class="label label-default">none</span>
+                  </li>
+                  {{end}}
+                </ul>
+            </td>
+            <td class="labels">
+                {{$labels := .Labels.Map }}
+                <ul style="list-style-type:none">
+                  {{range $label, $value := $labels}}
+                    <li>
+                      <span class="label label-primary">{{$label}}="{{$value}}"</span>
+                    </li>
+                  {{else}}
+                    <li>
+                      <span class="label label-default">Dropped</span>
+                    </li>
+                  {{end}}
+                </ul>
+            </td>
+          </tr>
+        {{end}}
+        </tbody>
+      </table>
+    </div>
+    {{ end }}
+  </div>
+
+{{end}}

web/ui/templates/targets.html

@@ -13,7 +13,7 @@
       </button>
     </div>
-    {{range $job, $pool := .TargetPools }}
+    {{range $job, $pool := .TargetPools}}
     {{$healthy := numHealthy $pool}}
     {{$total := len $pool}}

web/web.go

@@ -216,6 +216,7 @@ func New(logger log.Logger, o *Options) *Handler {
 	router.Get("/rules", readyf(instrf("rules", h.rules)))
 	router.Get("/targets", readyf(instrf("targets", h.targets)))
 	router.Get("/version", readyf(instrf("version", h.version)))
+	router.Get("/service-discovery", readyf(instrf("servicediscovery", h.serviceDiscovery)))
 	router.Get("/heap", instrf("heap", h.dumpHeap))
@@ -584,6 +585,23 @@ func (h *Handler) rules(w http.ResponseWriter, r *http.Request) {
 	h.executeTemplate(w, "rules.html", h.ruleManager)
 }
+func (h *Handler) serviceDiscovery(w http.ResponseWriter, r *http.Request) {
+	var index []string
+	targets := h.targetManager.TargetMap()
+	for job := range targets {
+		index = append(index, job)
+	}
+	sort.Strings(index)
+	scrapeConfigData := struct {
+		Index   []string
+		Targets map[string][]*retrieval.Target
+	}{
+		Index:   index,
+		Targets: targets,
+	}
+	h.executeTemplate(w, "service-discovery.html", scrapeConfigData)
+}
+
 func (h *Handler) targets(w http.ResponseWriter, r *http.Request) {
 	// Bucket targets by job label
 	tps := map[string][]*retrieval.Target{}