+++ title = "Redis Streams" availability = "v1.5+" maintainer = "Community" description = "Scale applications based on Redis Streams." go_file = "redis_streams_scaler" +++ ### Trigger Specification Redis 5.0 introduced [Redis Streams](https://redis.io/topics/streams-intro) which is an append-only log data structure. One of its features includes [`Consumer Groups`](https://redis.io/topics/streams-intro#consumer-groups), that allows a group of clients to co-operate consuming a different portion of the same stream of messages. There are three ways to configure `redis-streams` trigger: 1. Based on the *Pending Entries List* (see [`XPENDING`](https://redis.io/commands/xpending)) for a specific Consumer Group of a Redis Stream 2. Based on the *Stream Length* (see [`XLEN`](https://redis.io/commands/xlen)) 3. Based on the *Consumer Group Lag* (see [`XINFO GROUPS`](https://redis.io/commands/xinfo-groups/)). This is the only configuration that supports scaling down to 0. IMPORTANT: Redis 7+ is required for this feature to run. ```yaml triggers: - type: redis-streams metadata: address: localhost:6379 # Required if host and port are not provided. Format - host:port host: localhost # Required if address is not provided port: "6379" # Required if address is not provided and host has been provided. usernameFromEnv: REDIS_USERNAME # optional (can also use authenticationRef) passwordFromEnv: REDIS_PASSWORD # optional (can also use authenticationRef) stream: my-stream # Required - name of the Redis Stream consumerGroup: my-consumer-group # optional - name of consumer group associated with Redis Stream pendingEntriesCount: "10" # optional - number of entries in the Pending Entries List for the specified consumer group in the Redis Stream streamLength: "50" # optional - Redis stream length, alternative to pendingEntriesCount scaler trigger lagCount: "5" # optional - number of lagging entries in the consumer group, alternative to pendingEntriesCount scaler trigger activationLagCount: "3" # required if lagCount is provided - lag count at which scaler triggers enableTLS: "false" # optional unsafeSsl: "false" # optional databaseIndex: "0" # optional # Alternatively, you can use existing environment variables to read configuration from: # See details in "Parameter list" section addressFromEnv: REDIS_ADDRESS # Optional. You can use this instead of `address` parameter hostFromEnv: REDIS_HOST # Optional. You can use this instead of `host` parameter portFromEnv: REDIS_PORT # Optional. You can use this instead of `port` parameter ``` **Parameter list:** - `address` - The host and port of the Redis server in the format `host:port`, for example `my-redis:6379`. > As an alternative to the `address` field, the user can specify `host` and `port` parameters. - `host` - The host of the Redis server. > It is not required if `address` has been provided. - `port` - The port of the Redis server. > It is only to be used along with the `host`/`hostFromEnv` attribute and not required if `address` has been provided. - `usernameFromEnv` - Name of the environment variable your deployment uses to get the Redis username. (Optional) - `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. > Setting the `consumerGroup` causes the scaler to operate on `pendingEntriesCount`. Lack of `consumerGroup` will cause the scaler to be based on `streamLength` - `pendingEntriesCount` - Threshold for the number of `Pending Entries List`. This is the average target value to scale the workload. (Default: `5`, Optional) - `streamLength` - Threshold for stream length, alternative average target value to scale workload. (Default: `5`, Optional) - `databaseIndex` - The Redis database index. Defaults to `0` if not specified. - `lagCount` - Threshold for the consumer group lag number, alternative average target value to scale workload. (Default: `5`, Optional) - `activationLagCount` - Lag count threshold at which to start scaling. Any average lag count below this value will not trigger the scaler. (Default: `0`, Optional) - `enableTLS` - Allow a connection to Redis using tls. (Values: `true`, `false`, Default: `false`, Optional) - `unsafeSsl` - Used for skipping certificate check e.g: using self-signed certs. (Values: `true`,`false`, Default: `false`, Optional, This requires `enableTLS: true`) 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: - `addressFromEnv` - The host and port of the Redis server, similar to `address`, but reads it from an environment variable on the scale target. Name of the environment variable your deployment uses to get the Redis server URL. The resolved host should follow a format like `my-redis:6379`. - `hostFromEnv` - The host of the Redis server, similar to `host`, but reads it from an environment variable on the scale target. - `portFromEnv` - The port of the Redis server, similar to `port`, but reads it from an environment variable on the scale target. ### Authentication Parameters The scaler supports two modes of authentication: #### Using username/password authentication Use the `username` and `password` field in the `metadata` to specify the name of an environment variable that your deployment uses to get the Redis username/password. This is usually resolved from a `Secret V1` or a `ConfigMap V1` collections. `env` and `envFrom` are both supported. Here is an example: ```yaml 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-streams metadata: addressFromEnv: REDIS_HOST usernameFromEnv: REDIS_USERNAME # name of the environment variable in the Deployment 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: ```yaml apiVersion: v1 kind: Secret metadata: name: redis-streams-auth type: Opaque data: redis_username: redis_password: --- apiVersion: keda.sh/v1alpha1 kind: TriggerAuthentication metadata: name: keda-redis-stream-triggerauth spec: secretTargetRef: - parameter: username name: redis-streams-auth # name of the Secret key: redis_username # name of the key in the Secret - parameter: password name: redis-streams-auth # 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-streams metadata: address: localhost:6379 stream: my-stream consumerGroup: consumer-group-1 pendingEntriesCount: "10" authenticationRef: name: keda-redis-stream-triggerauth # name of the TriggerAuthentication resource ``` #### Using `streamLength` To scale based on redis stream `XLEN` don't set `consumerGroup`. Example: ```yaml apiVersion: keda.sh/v1alpha1 kind: ScaledObject metadata: name: redis-streams-scaledobject namespace: default spec: scaleTargetRef: name: redis-streams-consumer pollingInterval: 20 cooldownPeriod: 200 maxReplicaCount: 10 minReplicaCount: 1 triggers: - type: redis-streams metadata: addressFromEnv: REDIS_HOST usernameFromEnv: REDIS_USERNAME # name of the environment variable in the Deployment passwordFromEnv: REDIS_PASSWORD # name of the environment variable in the Deployment stream: my-stream streamLength: "50" ``` #### Using `lagCount` To scale based on redis stream `XINFO GROUPS`, be sure to set `activationLagCount`. Example: ```yaml 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-streams metadata: addressFromEnv: REDIS_HOST usernameFromEnv: REDIS_USERNAME # name of the environment variable in the Deployment passwordFromEnv: REDIS_PASSWORD # name of the environment variable in the Deployment stream: my-stream consumerGroup: consumer-group-1 lagCount: "10" activationLagCount: "3" ```