Web: Add pre-relabel labels to status page.

Figuring out what's going on with the new service discovery
and labels is difficult. Add a popover with the labels
to the target table to make things simpler, and help
discovery of potentially useful labels.

retrieval/target.go

@@ -156,6 +156,8 @@ type Target struct {
 	sync.RWMutex
 	// url is the URL to be scraped. Its host is immutable.
 	url *url.URL
+	// Labels before any processing.
+	metaLabels clientmodel.LabelSet
 	// Any base labels that are added to this target and its metrics.
 	baseLabels clientmodel.LabelSet
 	// What is the deadline for the HTTP or HTTPS against this endpoint.
@@ -165,7 +167,7 @@ type Target struct {
 }
 
 // NewTarget creates a reasonably configured target for querying.
-func NewTarget(cfg *config.ScrapeConfig, baseLabels clientmodel.LabelSet) *Target {
+func NewTarget(cfg *config.ScrapeConfig, baseLabels, metaLabels clientmodel.LabelSet) *Target {
 	t := &Target{
 		url: &url.URL{
 			Host: string(baseLabels[clientmodel.AddressLabel]),
@@ -174,7 +176,7 @@ func NewTarget(cfg *config.ScrapeConfig, baseLabels clientmodel.LabelSet) *Targe
 		scraperStopping: make(chan struct{}),
 		scraperStopped:  make(chan struct{}),
 	}
-	t.Update(cfg, baseLabels)
+	t.Update(cfg, baseLabels, metaLabels)
 	return t
 }
 
@@ -185,7 +187,7 @@ func (t *Target) Status() *TargetStatus {
 
 // Update overwrites settings in the target that are derived from the job config
 // it belongs to.
-func (t *Target) Update(cfg *config.ScrapeConfig, baseLabels clientmodel.LabelSet) {
+func (t *Target) Update(cfg *config.ScrapeConfig, baseLabels, metaLabels clientmodel.LabelSet) {
 	t.Lock()
 	defer t.Unlock()
 
@@ -199,6 +201,7 @@ func (t *Target) Update(cfg *config.ScrapeConfig, baseLabels clientmodel.LabelSe
 	t.deadline = time.Duration(cfg.ScrapeTimeout)
 	t.httpClient = httputil.NewDeadlineClient(time.Duration(cfg.ScrapeTimeout))
 
+	t.metaLabels = metaLabels
 	t.baseLabels = clientmodel.LabelSet{}
 	// All remaining internal labels will not be part of the label set.
 	for name, val := range baseLabels {
@@ -400,6 +403,17 @@ func (t *Target) BaseLabels() clientmodel.LabelSet {
 	return lset
 }
 
+// MetaLabels returns a copy of the target's labels before any processing.
+func (t *Target) MetaLabels() clientmodel.LabelSet {
+	t.RLock()
+	defer t.RUnlock()
+	lset := make(clientmodel.LabelSet, len(t.metaLabels))
+	for ln, lv := range t.metaLabels {
+		lset[ln] = lv
+	}
+	return lset
+}
+
 func recordScrapeHealth(
 	sampleAppender storage.SampleAppender,
 	timestamp clientmodel.Timestamp,

retrieval/targetmanager.go

@@ -225,14 +225,14 @@ func (tm *TargetManager) updateTargetGroup(tgroup *config.TargetGroup, cfg *conf
 					break
 				}
 			}
-			// Update the exisiting target and discard the new equivalent.
+			// Update the existing target and discard the new equivalent.
 			// Otherwise start scraping the new target.
 			if match != nil {
 				// Updating is blocked during a scrape. We don't want those wait times
 				// to build up.
 				wg.Add(1)
 				go func(t *Target) {
-					match.Update(cfg, t.fullLabels())
+					match.Update(cfg, t.fullLabels(), t.metaLabels)
 					wg.Done()
 				}(tnew)
 				newTargets[i] = match
@@ -351,6 +351,8 @@ func (tm *TargetManager) targetsFromGroup(tg *config.TargetGroup, cfg *config.Sc
 			return nil, fmt.Errorf("instance %d in target group %s has no address", i, tg)
 		}
 
+		preRelabelLabels := labels
+
 		labels, err := Relabel(labels, cfg.RelabelConfigs...)
 		if err != nil {
 			return nil, fmt.Errorf("error while relabeling instance %d in target group %s: %s", i, tg, err)
@@ -367,7 +369,7 @@ func (tm *TargetManager) targetsFromGroup(tg *config.TargetGroup, cfg *config.Sc
 				delete(labels, ln)
 			}
 		}
-		tr := NewTarget(cfg, labels)
+		tr := NewTarget(cfg, labels, preRelabelLabels)
 		targets = append(targets, tr)
 	}
 

web/templates/_base.html

@@ -4,11 +4,17 @@
     <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
     <title>Prometheus Time Series Collection and Processing Server</title>
     <script src="{{ pathPrefix }}/static/vendor/js/jquery.min.js"></script>
+    <script src="{{ pathPrefix }}/static/vendor/bootstrap-3.3.1/js/bootstrap.min.js"></script>
 
     <link type="text/css" rel="stylesheet" href="{{ pathPrefix }}/static/vendor/bootstrap-3.3.1/css/bootstrap.min.css">
     <link type="text/css" rel="stylesheet" href="{{ pathPrefix }}/static/css/prometheus.css">
 
-    <script>var PATH_PREFIX = "{{ pathPrefix }}";</script>
+    <script>
+      var PATH_PREFIX = "{{ pathPrefix }}";
+      $(function () {
+        $('[data-toggle="tooltip"]').tooltip()
+      })
+    </script>
 
     {{template "head" .}}
   </head>

web/templates/status.html

@@ -56,7 +56,9 @@
                 </span>
               </td>
               <td>
-                {{stripLabels .BaseLabels "job" "instance"}}
+                <a href="#" data-toggle="tooltip" title="" data-original-title="Before Relabel: {{.MetaLabels}}">
+                  {{or (stripLabels .BaseLabels "job" "instance") "{}"}}
+                </a>
               </td>
               <td>
                 {{if .Status.LastScrape.IsZero}}Never{{else}}{{since .Status.LastScrape}} ago{{end}}