feat: Show zero lag consumer groups and include group state in lagCmd…

… output

cmd/kaf/topic.go

@@ -335,6 +335,7 @@ var deleteTopicCmd = &cobra.Command{
 		}
 	},
 }
+
 var lagCmd = &cobra.Command{
 	Use:   "lag",
 	Short: "Display the total lags for each consumer group",
@@ -344,49 +345,68 @@ var lagCmd = &cobra.Command{
 		admin := getClusterAdmin()
 		defer admin.Close()
 
-		topicDetails, err := admin.DescribeTopics([]string{args[0]})
-		if err != nil {
+		// Describe the topic
+		topicDetails, err := admin.DescribeTopics([]string{topic})
+		if err != nil || len(topicDetails) == 0 {
 			errorExit("Unable to describe topics: %v\n", err)
 		}
+
+		// Get the list of partitions for the topic
 		partitions := make([]int32, 0, len(topicDetails[0].Partitions))
 		for _, partition := range topicDetails[0].Partitions {
 			partitions = append(partitions, partition.ID)
 		}
-		highWatermarks := getHighWatermarks(args[0], partitions)
+		highWatermarks := getHighWatermarks(topic, partitions)
 
-		var groups []string
+		// List all consumer groups
 		consumerGroups, err := admin.ListConsumerGroups()
 		if err != nil {
 			errorExit("Unable to list consumer groups: %v\n", err)
 		}
+
+		var groups []string
 		for group := range consumerGroups {
 			groups = append(groups, group)
 		}
+
+		// Describe all consumer groups
 		groupsInfo, err := admin.DescribeConsumerGroups(groups)
 		if err != nil {
 			errorExit("Unable to describe consumer groups: %v\n", err)
 		}
-		var lagInfo = make(map[string]int64)
-		for _, v := range groupsInfo {
+
+		// Calculate lag for each group
+		lagInfo := make(map[string]int64)
+		groupStates := make(map[string]string) // To store the state of each group
+		for _, group := range groupsInfo {
 			var sum int64
-			for _, member := range v.Members {
+			show := false
+			for _, member := range group.Members {
 				assignment, err := member.GetMemberAssignment()
 				if err != nil || assignment == nil {
 					continue
 				}
+
+				metadata, err := member.GetMemberMetadata()
+				if err != nil || metadata == nil {
+					continue
+				}
+
 				if topicPartitions, exist := assignment.Topics[topic]; exist {
-					resp, err := admin.ListConsumerGroupOffsets(v.GroupId, map[string][]int32{topic: topicPartitions})
+					show = true
+					resp, err := admin.ListConsumerGroupOffsets(group.GroupId, map[string][]int32{topic: topicPartitions})
 					if err != nil {
-						fmt.Fprintf(os.Stderr, "Error fetching offsets for group %s: %v\n", v.GroupId, err)
+						fmt.Fprintf(os.Stderr, "Error fetching offsets for group %s: %v\n", group.GroupId, err)
 						continue
 					}
+
 					if blocks, ok := resp.Blocks[topic]; ok {
 						for pid, block := range blocks {
 							if hwm, ok := highWatermarks[pid]; ok {
 								if block.Offset > hwm {
-									fmt.Fprintf(os.Stderr, "Warning: Consumer offset (%d) is greater than high watermark (%d) for partition %d in group %s\n", block.Offset, hwm, pid, v.GroupId)
-									// You might choose to set the lag to 0 in this case
-									// sum += 0
+									fmt.Fprintf(os.Stderr, "Warning: Consumer offset (%d) is greater than high watermark (%d) for partition %d in group %s\n", block.Offset, hwm, pid, group.GroupId)
+								} else if block.Offset < 0 {
+									// Skip partitions with negative offsets
 								} else {
 									sum += hwm - block.Offset
 								}
@@ -395,16 +415,20 @@ var lagCmd = &cobra.Command{
 					}
 				}
 			}
-			if sum > 0 {
-				lagInfo[v.GroupId] = sum
+
+			if show && sum >= 0 {
+				lagInfo[group.GroupId] = sum
+				groupStates[group.GroupId] = group.State // Store the state of the group
 			}
 		}
+
+		// Print the lag information along with group state
 		w := tabwriter.NewWriter(outWriter, tabwriterMinWidth, tabwriterWidth, tabwriterPadding, tabwriterPadChar, tabwriterFlags)
 		if !noHeaderFlag {
-			fmt.Fprintf(w, "GROUP ID\tLAG\n")
+			fmt.Fprintf(w, "GROUP ID\tSTATE\tLAG\n")
 		}
 		for group, lag := range lagInfo {
-			fmt.Fprintf(w, "%v\t%v\n", group, lag)
+			fmt.Fprintf(w, "%v\t%v\t%v\n", group, groupStates[group], lag)
 		}
 		w.Flush()
 	},