Module cluster 

Runtime state shared across replicas through Redis (18.22.0). Runtime state shared across replicas (18.22.0, #76).

With [cluster] redis = "host:port" (else [acme] redis), changes made on one replica through the admin API, rws ctl or the MCP tools — the IP blocklist, maintenance mode, drained backends, feature flags and cache purges — reach every replica within about a second.

How: one JSON document per cluster (<prefix>state) holds the shared state and a version. A change is applied locally first, then sent to Redis as an operation that a Lua script applies to the document atomically (Redis’s cjson), so concurrent changes on different replicas never overwrite each other. Every replica reads the document once a second and, when its version moved, makes its own state match. With Redis down, local changes still apply and are sent once it’s back; a replica that starts adopts the document. Each replica also writes a heartbeat into <prefix>nodes, which GET /admin/api/v1/status lists.

The admin operations (crate::admin::ops) publish; code that changes crate::blocklist::global or the feature store directly stays local.

Structs

ClusterSync

One replica’s view of the cluster: the store, what it applied last, and operations waiting for the store to come back.

MemoryStore

The document in memory: for tests (several replicas in one process) and as a reference for the Lua script’s rules.

ProcessState

The process-wide blocklist, maintenance switch, upstream drains, feature flags and named caches.

RedisStore

The document in Redis.

State

The shared document.

Enums

Op

One change to the shared state.

Constants

HEARTBEAT

How often a heartbeat is written; nodes silent for 60 s drop out.

POLL

How often the shared document is read.

PURGES_KEPT

Purges kept in the document (older ones have been applied by then).

RWS_CONFIG_CLUSTER_PREFIX

RWS_CONFIG_CLUSTER_REDIS

[cluster] settings.

RWS_CONFIG_CLUSTER_REDIS_PASSWORD

Traits

Local

Makes this process’s runtime state match a State; the default applies to the process-wide stores.

Store

Where the shared document lives.

Functions

publish

Send a change made on this replica to the others (no-op without [cluster]).

start_from_env

The binary’s entry point: with [cluster] redis (or [acme] redis), start syncing on a thread of its own.

status_json

The cluster status for the admin API, or None without [cluster].