Support redis cluster

- Added `--redis-cluster-nodes` flag
- Display cluster information in redis info page

redis_info_handlers.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/go-redis/redis/v8"
+	"github.com/hibiken/asynq"
 )
 
 // ****************************************************************************
@@ -18,21 +19,86 @@ type RedisInfoResponse struct {
 	Addr    string            `json:"address"`
 	Info    map[string]string `json:"info"`
 	RawInfo string            `json:"raw_info"`
+	Cluster bool              `json:"cluster"`
+
+	// Following fields are only set when connected to redis cluster.
+	RawClusterNodes string               `json:"raw_cluster_nodes"`
+	QueueLocations  []*QueueLocationInfo `json:"queue_locations"`
 }
 
-func newRedisInfoHandlerFunc(rdb *redis.Client) http.HandlerFunc {
+type QueueLocationInfo struct {
+	Queue   string   `json:"queue"`   // queue name
+	KeySlot int64    `json:"keyslot"` // cluster key slot for the queue
+	Nodes   []string `json:"nodes"`   // list of cluster node addresses
+}
+
+func newRedisInfoHandlerFunc(client *redis.Client) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		ctx := context.Background()
-		res, err := rdb.Info(ctx).Result()
+		res, err := client.Info(ctx).Result()
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return
 		}
 		info := parseRedisInfo(res)
 		resp := RedisInfoResponse{
-			Addr:    rdb.Options().Addr,
+			Addr:    client.Options().Addr,
 			Info:    info,
 			RawInfo: res,
+			Cluster: false,
+		}
+		if err := json.NewEncoder(w).Encode(resp); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+	}
+}
+
+func newRedisClusterInfoHandlerFunc(client *redis.ClusterClient, inspector *asynq.Inspector) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		ctx := context.Background()
+		rawClusterInfo, err := client.ClusterInfo(ctx).Result()
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		info := parseRedisInfo(rawClusterInfo)
+		rawClusterNodes, err := client.ClusterNodes(ctx).Result()
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		queues, err := inspector.Queues()
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		var queueLocations []*QueueLocationInfo
+		for _, qname := range queues {
+			q := QueueLocationInfo{Queue: qname}
+			q.KeySlot, err = inspector.ClusterKeySlot(qname)
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+			nodes, err := inspector.ClusterNodes(qname)
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+			for _, n := range nodes {
+				q.Nodes = append(q.Nodes, n.Addr)
+			}
+			queueLocations = append(queueLocations, &q)
+		}
+
+		resp := RedisInfoResponse{
+			Addr:            strings.Join(client.Options().Addrs, ","),
+			Info:            info,
+			RawInfo:         rawClusterInfo,
+			Cluster:         true,
+			RawClusterNodes: rawClusterNodes,
+			QueueLocations:  queueLocations,
 		}
 		if err := json.NewEncoder(w).Encode(resp); err != nil {
 			http.Error(w, err.Error(), http.StatusInternalServerError)