fixes

internal/component/discovery/target.go

@@ -41,22 +41,23 @@ func ComponentTargetsToPromTargetGroups(jobName string, tgs []Target) map[string
 		targetsWithCommonGroupLabels[fp] = append(targetsWithCommonGroupLabels[fp], t)
 	}
 
-	allGroups := make(map[string][]*targetgroup.Group, len(targetsWithCommonGroupLabels))
+	allGroups := make([]*targetgroup.Group, 0, len(targetsWithCommonGroupLabels))
 
 	groupIndex := 0
 	for _, targetsInGroup := range targetsWithCommonGroupLabels {
-		groupName := fmt.Sprintf("%s_%d", jobName, groupIndex)
-		groupTargets := make([]commonlabels.LabelSet, len(targetsInGroup))
+		sharedLabels := targetsInGroup[0].group // all have the same group labels.
+		individualLabels := make([]commonlabels.LabelSet, len(targetsInGroup))
 		for i, target := range targetsInGroup {
-			groupTargets[i] = target.own
+			individualLabels[i] = target.own
 		}
 		promGroup := &targetgroup.Group{
-			Source: groupName,
-			Labels: targetsInGroup[0].group,
+			Source:  fmt.Sprintf("%s_part_%d", jobName, groupIndex),
+			Labels:  sharedLabels,
+			Targets: individualLabels,
 		}
-		allGroups[groupName] = append(allGroups[groupName], promGroup)
+		allGroups = append(allGroups, promGroup)
 	}
-	return allGroups
+	return map[string][]*targetgroup.Group{jobName: allGroups}
 }
 
 var EmptyTarget = Target{

internal/component/prometheus/scrape/scrape.go

@@ -480,16 +480,26 @@ func (c *Component) DebugInfo() interface{} {
 }
 
 func (c *Component) populatePromLabels(targets []discovery.Target, jobName string, args Arguments) []*scrape.Target {
+	// We need to call scrape.TargetsFromGroup to reuse the rather complex logic of populating labels on targets.
+	allTargets := make([]*scrape.Target, 0, len(targets))
 	lb := labels.NewBuilder(labels.EmptyLabels())
-	promTargets, errs := scrape.TargetsFromGroup(
-		discovery.ComponentTargetsToPromTargetGroups(jobName, targets)[jobName][0],
-		getPromScrapeConfigs(c.opts.ID, args),
-		false,                                /* noDefaultScrapePort - always false in this component */
-		make([]*scrape.Target, len(targets)), /* targets slice to reuse */
-		lb,
-	)
-	for _, err := range errs {
-		level.Warn(c.opts.Logger).Log("msg", "error while populating labels of targets using prom config", "err", err)
+	groups := discovery.ComponentTargetsToPromTargetGroups(jobName, targets)
+	for _, tgs := range groups {
+		for _, tg := range tgs {
+			promTargets, errs := scrape.TargetsFromGroup(
+				tg,
+				getPromScrapeConfigs(jobName, args),
+				false,                                /* noDefaultScrapePort - always false in this component */
+				make([]*scrape.Target, len(targets)), /* targets slice to reuse */
+				lb,
+			)
+			lb.Reset(labels.EmptyLabels())
+			for _, err := range errs {
+				level.Warn(c.opts.Logger).Log("msg", "error while populating labels of targets using prom config", "err", err)
+			}
+			allTargets = append(allTargets, promTargets...)
+		}
 	}
-	return promTargets
+
+	return allTargets
 }