node level circuit breakers

[justinreddit]

Is it possible to configure circuit breakers at the request level for a node? In cases of node degradation, we'd like to continue serving traffic for other nodes in the cluster and partition off bad nodes till they recover.

[rueian]

The closest we have is the combination of SendToReplicas and ReplicaSelector. This allows you to specify which replica to send data to for each slot whenever the cluster topology in rueidis needs to be updated, such as due to a network error.

client, err := rueidis.NewClient(rueidis.ClientOption{
	InitAddress:         []string{"address.example.com:6379"},
	SendToReplicas: func(cmd rueidis.Completed) bool {
		return cmd.IsReadOnly()
	},
	ReplicaSelector: func(slot uint16, replicas []rueidis.ReplicaInfo) int {
		for i, replica := range replicas {
			return i // return the index of a healthy replica
		}
		return -1 // or send to the primary.
	},
})