feat: add new metric kafka_consumergroup_topicmembers

.gitignore

@@ -24,3 +24,5 @@ kafka_exporter
 # Test configuration
 test/
 .DS_Store
+
+*.strimzi

.promu.yml

@@ -11,3 +11,9 @@ build:
 tarball:
     files:
         - LICENSE
+crossbuild:
+    platforms:
+        - linux/amd64
+        - linux/s390x
+        - linux/arm64
+        - linux/ppc64le

Makefile

@@ -48,10 +48,12 @@ docker: build
 	@docker build -t "$(DOCKER_IMAGE_NAME):$(DOCKER_IMAGE_TAG)" --build-arg BIN_DIR=. .
 
 push: crossbuild
-	@echo ">> building and pushing multi-arch docker images, $(DOCKER_USERNAME),$(DOCKER_IMAGE_NAME),$(GIT_TAG_NAME)"
+ifneq (, $(DOCKER_PASSWORD))
 	@docker login -u $(DOCKER_USERNAME) -p $(DOCKER_PASSWORD)
+endif
+	@echo ">> building and pushing multi-arch docker images, $(DOCKER_USERNAME),$(DOCKER_IMAGE_NAME),$(GIT_TAG_NAME)"
 	@docker buildx create --use
-	@docker buildx build -t "$(DOCKER_USERNAME)/$(DOCKER_IMAGE_NAME):$(GIT_TAG_NAME)" \
+	@docker buildx build -t "$(DOCKER_IMAGE_NAME):$(DOCKER_IMAGE_TAG)" \
 		--output "$(PUSHTAG)" \
 		--platform "$(DOCKER_PLATFORMS)" \
 		.
@@ -106,8 +108,8 @@ lint: golangci-lint
 golangci-lint:
 ifeq (, $(shell which golangci-lint))
 	@GOOS=$(shell uname -s | tr A-Z a-z) \
-    		GOARCH=$(subst x86_64,amd64,$(patsubst i%86,386,$(shell uname -m))) \
-    		$(GO) install github.com/golangci/golangci-lint/cmd/golangci-lint@v1.52.2
+	GOARCH=$(subst x86_64,amd64,$(patsubst i%86,386,$(shell uname -m))) \
+	$(GO) install github.com/golangci/golangci-lint/cmd/golangci-lint@v1.52.2
 GOLANG_LINT=$(shell go env GOPATH)/bin/golangci-lint
 else
 GOLANG_LINT=$(shell which golangci-lint)

kafka_exporter.go

@@ -56,6 +56,7 @@ var (
 	consumergroupLagSum                *prometheus.Desc
 	consumergroupLagZookeeper          *prometheus.Desc
 	consumergroupMembers               *prometheus.Desc
+	consumergroupTopicMembers          *prometheus.Desc
 )
 
 // Exporter collects Kafka stats from the given server and exports them using
@@ -594,9 +595,29 @@ func (e *Exporter) collect(ch chan<- prometheus.Metric) {
 					}
 				}
 			}
+
 			ch <- prometheus.MustNewConstMetric(
 				consumergroupMembers, prometheus.GaugeValue, float64(len(group.Members)), group.GroupId,
 			)
+
+			uniqueTopics := make(map[string]int)
+			for _, member := range group.Members {
+				assignment, err := member.GetMemberAssignment()
+				if err != nil || assignment == nil {
+					klog.Errorf("Cannot get GetMemberAssignment of group member %v : %v", member, err)
+					continue
+				}
+				for topic := range assignment.Topics {
+					uniqueTopics[topic]++
+				}
+			}
+
+			for topic, count := range uniqueTopics {
+				ch <- prometheus.MustNewConstMetric(
+					consumergroupTopicMembers, prometheus.GaugeValue, float64(count), group.GroupId, topic,
+				)
+			}
+
 			offsetFetchResponse, err := broker.FetchOffset(&offsetFetchRequest)
 			if err != nil {
 				klog.Errorf("Cannot get offset of group %s: %v", group.GroupId, err)
@@ -896,6 +917,12 @@ func setup(
 		[]string{"consumergroup"}, labels,
 	)
 
+	consumergroupTopicMembers = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "consumergroup", "topicmembers"),
+		"Amount of members in a consumer group against a topic",
+		[]string{"consumergroup", "topic"}, labels,
+	)
+
 	if logSarama {
 		sarama.Logger = log.New(os.Stdout, "[sarama] ", log.LstdFlags)
 	}