fix: [CCPOKR-12770] Redis support for services to start under docker or localhost when running locally. (#3170)

* fix: Add a way to provide different redis host depending on whether it is running inside docker or localhost.

* fix: Getting the envar in RedisConfig didn't work so explicitly fetching it in RedisClusterModule and setting the hostname accordingly which works.

Author: nssherpa

misk-redis/src/main/kotlin/misk/redis/RedisClusterModule.kt

@@ -90,10 +90,15 @@ class RedisClusterModule @JvmOverloads constructor(
       //CLIENT SETINFO is only supported in Redis v7.2+
       .clientSetInfoConfig(ClientSetInfoConfig.DISABLED)
       .build()
+
+    // We want to support services running both under docker and localhost when running locally and this is a way to support that.
+    // If a hostname is provided, it will always take precedence over the environment variable.
+    val redisHost = replicationGroup.configuration_endpoint.hostname?.takeUnless { it.isNullOrBlank() } ?: System.getenv("REDIS_HOST") ?: "127.0.0.1"
+
     return JedisCluster(
       setOf(
         HostAndPort(
-          replicationGroup.configuration_endpoint.hostname,
+          redisHost,
           replicationGroup.configuration_endpoint.port
         )
       ),

misk-redis/src/main/kotlin/misk/redis/RedisConfig.kt

@@ -18,6 +18,6 @@ data class RedisReplicationGroupConfig @JvmOverloads constructor(
 )
 
 data class RedisNodeConfig(
-  val hostname: String,
+  val hostname: String?,
   val port: Int
 )