Trigger Specification

Redis 5.0 introduced Redis Streams which is an append-only log data structure.

One of its features includes Consumer Groups, that allows a group of clients to co-operate consuming a different portion of the same stream of messages.

This specification describes the redis-cluster-streams trigger that scales based on the Pending Entries List (see XPENDING) for a specific Consumer Group of a Redis Stream and supports Redis Cluster topology.

triggers: - type: redis-cluster-streams  metadata:  addresses: localhost:6379 # Required if hosts and ports are not provided. Format - comma separated list of host:port  hosts: localhost # Comma separated lists of hosts. Required if address is not provided  ports: "6379" # Comma separated lists of ports. Required if addresses are not provided and hosts has been provided.  passwordFromEnv: REDIS_PASSWORD # optional (can also use authenticationRef)  stream: my-stream # Required - name of the Redis Stream  consumerGroup: my-consumer-group # Required - name of consumer group associated with Redis Stream  pendingEntriesCount: "10" # Required - number of entries in the Pending Entries List for the specified consumer group in the Redis Stream  enableTLS: "false" # optional  # Alternatively, you can use existing environment variables to read configuration from:  # See details in "Parameter list" section  addressesFromEnv: REDIS_ADDRESSES # Optional. You can use this instead of `addresses` parameter  hostsFromEnv: REDIS_HOSTS # Optional. You can use this instead of `hosts` parameter  portsFromEnv: REDIS_PORTS # Optional. You can use this instead of `ports` parameter 

Parameter list:

• addresses - Comma separated list of hosts and ports of Redis Cluster nodes in the format host:port for example node1:6379, node2:6379, node3:6379.

As an alternative to the addresses field, the user can specify hosts and ports parameters.

• hosts - Comma separated list of hosts of Redis Cluster nodes.

It is not required if addresses has been provided.

• ports: Comma separated list of ports for corresponding hosts of Redis Cluster nodes.

It is only to be used along with the hosts/hostsFromEnv attribute and not required if addresses has been provided.

• passwordFromEnv - Name of the environment variable your deployment uses to get the Redis password. (Optional)

• stream - Name of the Redis Stream.

• consumerGroup - Name of the Consumer group associated with Redis Stream.

• pendingEntriesCount - Threshold for the number of Pending Entries List. This is the average target value to scale the workload. (Default: 5, Optional)

• enableTLS - Allow a connection to Redis using tls. (Values: true, false, Default: false, Optional)

⚠️ WARNING: In this version, enableTLS: true automatically skips the certificate verification which is insecure. Use v2.9 or above to properly verify the server certificate.

Some parameters could be provided using environmental variables, instead of setting them directly in metadata. Here is a list of parameters you can use to retrieve values from environment variables:

• addressesFromEnv - The hosts and corresponding ports of Redis Cluster nodes, similar to addresses, but reads it from an environment variable on the scale target. Name of the environment variable your deployment uses to get the URLs of Redis Cluster nodes. The resolved hosts should follow a format like node1:6379, node2:6379, node3:6379 ....
• hostsFromEnv - The hosts of the Redis Cluster nodes, similar to hosts, but reads it from an environment variable on the scale target.
• portsFromEnv - The corresponding ports for the hosts of Redis Cluster nodes, similar to ports, but reads it from an environment variable on the scale target.

Authentication Parameters

The scaler supports two modes of authentication:

Password Authentication:

• password - Redis password to authenticate with.

Using password authentication

Use the password field in the metadata to specify the name of an environment variable that your deployment uses to get the Redis password.

This is usually resolved from a Secret V1 or a ConfigMap V1 collections. env and envFrom are both supported.

Here is an example:

apiVersion: keda.sh/v1alpha1 kind: ScaledObject metadata:  name: redis-streams-scaledobject  namespace: default spec:  scaleTargetRef:  name: redis-streams-consumer  pollingInterval: 15  cooldownPeriod: 200  maxReplicaCount: 25  minReplicaCount: 1  triggers:  - type: redis-cluster-streams  metadata:  addressesFromEnv: REDIS_ADDRESSES  passwordFromEnv: REDIS_PASSWORD # name of the environment variable in the Deployment  stream: my-stream  consumerGroup: consumer-group-1  pendingEntriesCount: "10" 

Using TriggerAuthentication

You can use TriggerAuthentication CRD to configure the authentication. For example:

apiVersion: v1 kind: Secret metadata:  name: redis-streams-password type: Opaque data:  redis_password: <encoded redis password> --- apiVersion: keda.sh/v1alpha1 kind: TriggerAuthentication metadata:  name: keda-redis-stream-triggerauth spec:  secretTargetRef:  - parameter: password  name: redis-streams-password # name of the Secret  key: redis_password # name of the key in the Secret --- apiVersion: keda.sh/v1alpha1 kind: ScaledObject metadata:  name: redis-streams-scaledobject  namespace: default spec:  scaleTargetRef:  name: redis-streams-consumer  pollingInterval: 15  cooldownPeriod: 200  maxReplicaCount: 25  minReplicaCount: 1  triggers:  - type: redis-cluster-streams  metadata:  address: node1:6379, node2:6379, node3:6379  stream: my-stream  consumerGroup: consumer-group-1  pendingEntriesCount: "10"  authenticationRef:  name: keda-redis-stream-triggerauth # name of the TriggerAuthentication resource