Routes writes to a Redis primary and eligible reads to replicas.

Redis.ReplicaSet can use explicitly configured replicas:

{:ok, redis} = Redis.ReplicaSet.start_link(
  primary: {"redis-primary", 6379},
  replicas: [{"redis-replica-1", 6379}, {"redis-replica-2", 6379}],
  read_preference: :prefer_replica
)

When :replicas is omitted, the process discovers online replicas from the primary's INFO REPLICATION response and periodically refreshes them:

Redis.ReplicaSet.start_link(
  primary: "redis://redis-primary:6379",
  read_preference: :replica
)

Redis' COMMAND metadata determines which commands are read-only. Unknown commands are routed to the primary. Module or application-specific commands can be added with :read_only_commands.

Read preferences

• :master (default) - route every command to the primary
• :replica - route reads to replicas. If replicas are configured but all fail, return the replica error. If none are available, use the primary.
• :prefer_replica - route reads to replicas and fall back to the primary when replica execution fails

Writes, mixed pipelines, transactions, and unknown commands always use the primary. Reads are distributed round-robin across connected replicas.

Options

• :primary - primary node as {host, port}, "host:port", Redis URI, or connection keyword list (required)
• :replicas - explicit list of replica nodes; omit for INFO discovery
• :read_preference - :master, :replica, or :prefer_replica
• :read_only_commands - extra command names that are safe on replicas
• :topology_refresh_interval - INFO refresh interval in milliseconds (default: 30_000; applies only to discovered topology)

Normal Redis.Connection options such as authentication, TLS, protocol, database, credential provider, and timeout are shared by all nodes. A node expressed as a keyword list or URI may override shared options.

Command, pipeline, and transaction calls accept response: :typed; see Redis.Response.