Acceptance Criteria

• We need to go over all the commands we emit and make sure they are idempotent, otherwise retrying could result in a corrupted state, lost tests etc.
• The redis gem has the necessary elements for that it's mostly just configuration.

Context

Sometimes our Redis server that handle the ci-queue workload experience a failover or some other availability issues.

When this happens it break builds even though it recovers pretty fast.

Examples

Error connecting to Redis on redacted.svc.cluster.local.:6379 (SocketError) (Redis::CannotConnectError)

./tmp/bundle/ruby/3.1.0/gems/redis-4.8.0/lib/redis/client.rb:162:in `call': MASTERDOWN Link with MASTER is down and replica-serve-stale-data is set to 'no'. (Redis::CommandError)

(that later one need to be better categorized by the redis gem though)

Solution

Ideally we'd be resilient to these small transient errors, this means retrying all or most commands and possibly waiting a bit before retrying. The redis gem has the necessary elements for that it's mostly just configuration.

However we need to go over all the commands we emit and make sure they are idempotent, otherwise retrying could result in a corrupted state, lost tests etc.

cc @ChrisBr