Make Cluster-bus port configurable with new cluster-port config (#9389)

Make Cluster-bus port configurable with new cluster-port config

redis.conf

@@ -1450,6 +1450,11 @@ lua-time-limit 5000
 #
 # cluster-node-timeout 15000
 
+# The cluster port is the port that the cluster bus will listen for inbound connections on. When set 
+# to the default value, 0, it will be bound to the command port + 10000. Setting this value requires 
+# you to specify the cluster bus port when executing cluster meet.
+# cluster-port 0
+
 # A replica of a failing master will avoid to start a failover if its data
 # looks too old.
 #

src/cluster.c

@@ -489,7 +489,8 @@ void deriveAnnouncedPorts(int *announced_port, int *announced_pport,
     /* Default announced ports. */
     *announced_port = port;
     *announced_pport = server.tls_cluster ? server.port : 0;
-    *announced_cport = port + CLUSTER_PORT_INCR;
+    *announced_cport = server.cluster_port ? server.cluster_port : port + CLUSTER_PORT_INCR;
+    
     /* Config overriding announced ports. */
     if (server.tls_cluster && server.cluster_announce_tls_port) {
         *announced_port = server.cluster_announce_tls_port;
@@ -570,7 +571,7 @@ void clusterInit(void) {
      * The other handshake port check is triggered too late to stop
      * us from trying to use a too-high cluster port number. */
     int port = server.tls_cluster ? server.tls_port : server.port;
-    if (port > (65535-CLUSTER_PORT_INCR)) {
+    if (!server.cluster_port && port > (65535-CLUSTER_PORT_INCR)) {
         serverLog(LL_WARNING, "Redis port number too high. "
                    "Cluster communication port is 10,000 port "
                    "numbers higher than your Redis port. "
@@ -581,9 +582,11 @@ void clusterInit(void) {
         serverLog(LL_WARNING, "No bind address is configured, but it is required for the Cluster bus.");
         exit(1);
     }
-    if (listenToPort(port+CLUSTER_PORT_INCR, &server.cfd) == C_ERR) {
+    int cport = server.cluster_port ? server.cluster_port : port + CLUSTER_PORT_INCR;
+    if (listenToPort(cport, &server.cfd) == C_ERR ) {
         exit(1);
     }
+    
     if (createSocketAcceptHandler(&server.cfd, clusterAcceptHandler) != C_OK) {
         serverPanic("Unrecoverable error creating Redis Cluster socket accept handler.");
     }

src/cluster.h

@@ -6,9 +6,9 @@
  *----------------------------------------------------------------------------*/
 
 #define CLUSTER_SLOTS 16384
-#define CLUSTER_OK 0          /* Everything looks ok */
-#define CLUSTER_FAIL 1        /* The cluster can't work */
-#define CLUSTER_NAMELEN 40    /* sha1 hex length */
+#define CLUSTER_OK 0            /* Everything looks ok */
+#define CLUSTER_FAIL 1          /* The cluster can't work */
+#define CLUSTER_NAMELEN 40      /* sha1 hex length */
 #define CLUSTER_PORT_INCR 10000 /* Cluster port = baseport + PORT_INCR */
 
 /* The following defines are amount of time, sometimes expressed as

src/config.c

@@ -2645,6 +2645,7 @@ standardConfig configs[] = {
     createIntConfig("timeout", NULL, MODIFIABLE_CONFIG, 0, INT_MAX, server.maxidletime, 0, INTEGER_CONFIG, NULL, NULL), /* Default client timeout: infinite */
     createIntConfig("replica-announce-port", "slave-announce-port", MODIFIABLE_CONFIG, 0, 65535, server.slave_announce_port, 0, INTEGER_CONFIG, NULL, NULL),
     createIntConfig("tcp-backlog", NULL, IMMUTABLE_CONFIG, 0, INT_MAX, server.tcp_backlog, 511, INTEGER_CONFIG, NULL, NULL), /* TCP listen backlog. */
+    createIntConfig("cluster-port", NULL, IMMUTABLE_CONFIG, 0, 65535, server.cluster_port, 0, INTEGER_CONFIG, NULL, NULL),    
     createIntConfig("cluster-announce-bus-port", NULL, MODIFIABLE_CONFIG, 0, 65535, server.cluster_announce_bus_port, 0, INTEGER_CONFIG, NULL, NULL), /* Default: Use +10000 offset. */
     createIntConfig("cluster-announce-port", NULL, MODIFIABLE_CONFIG, 0, 65535, server.cluster_announce_port, 0, INTEGER_CONFIG, NULL, NULL), /* Use server.port */
     createIntConfig("cluster-announce-tls-port", NULL, MODIFIABLE_CONFIG, 0, 65535, server.cluster_announce_tls_port, 0, INTEGER_CONFIG, NULL, NULL), /* Use server.tls_port */

src/server.h

@@ -1631,6 +1631,7 @@ struct redisServer {
                                    xor of NOTIFY_... flags. */
     /* Cluster */
     int cluster_enabled;      /* Is cluster enabled? */
+    int cluster_port;         /* Set the cluster port for a node. */
     mstime_t cluster_node_timeout; /* Cluster node timeout. */
     char *cluster_configfile; /* Cluster auto-generated config file name. */
     struct clusterState *cluster;  /* State of the cluster */

tests/unit/introspection.tcl

@@ -158,6 +158,7 @@ start_server {tags {"introspection"}} {
             bgsave_cpulist
             set-proc-title
             cluster-config-file
+            cluster-port
         }
 
         if {!$::tls} {