Support redis cluster readfrom strategy

[vaibhav-jain-exp]

Add configurable Redis read routing strategy

Changes

• Added readFrom configuration field for Redis Cluster mode
• Default changed from hardcoded REPLICA_PREFERRED to ANY for better load distribution
• Supports two options:
  • ANY (default): Distributes reads across all nodes (masters + replicas)
  • REPLICA_PREFERRED: Prefers replicas, falls back to master

Configuration

redis:
uri: "redis://cluster:6379"
useCluster: true
readFrom: "ANY" # or "REPLICA_PREFERRED"

[macroscopeapp]

Add Redis Cluster read routing control and document configuration in com.amplitude.util.redis.createRedisConnections

Introduce readFrom in com.amplitude.RedisConfiguration, read AMPLITUDE_REDIS_READ_FROM in fromEnv, parse values with com.amplitude.util.redis.parseReadFrom, and apply the strategy in cluster connections; update docs in README.md.

📍Where to Start

Start with com.amplitude.util.redis.createRedisConnections in core/src/main/kotlin/util/redis/RedisConnections.kt.

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Macroscope summarized 8283e8c.

[bgiori]

Since we have two options ANY and REPLICA_PREFERRED can we just make this a boolean that defaults false. E.g. readFromReplica where false=ANY and true=REPLICA_PREFERRED?

[vaibhav-jain-exp]

This could be extended to support more values if need arises in the future.