RabbitMQ Queue

Scale applications based on RabbitMQ Queue.

Availability: v1.0+ Maintainer: Microsoft

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Trigger Specification

This specification describes the rabbitmq trigger for RabbitMQ Queue.

triggers:
- type: rabbitmq
  metadata:
    host: amqp://localhost:5672/vhost # Optional. If not specified, it must be done by using TriggerAuthentication.
    protocol: auto # Optional. Specifies protocol to use, either amqp or http, or auto to autodetect based on the `host` value. Default value is auto.
    mode: QueueLength # QueueLength or MessageRate
    value: "100" # message backlog or publish/sec. target per instance
    queueName: testqueue
    vhostName: / # Optional. If not specified, use the vhost in the `host` connection string.
    # Alternatively, you can use existing environment variables to read configuration from:
    # See details in "Parameter list" section
    hostFromEnv: RABBITMQ_HOST # Optional. You can use this instead of `host` parameter

Parameter list:

host - Host of RabbitMQ with format <protocol>://<host>:<port>/vhost. The resolved host should follow a format like amqp://guest:password@localhost:5672/vhost or http://guest:password@localhost:15672/vhost. When using a username/password consider using hostFromEnv or a TriggerAuthentication.
queueName - Name of the queue to read message from.
mode - QueueLength to trigger on number of messages in the queue. MessageRate to trigger on the publish rate into the queue. (Values: QueueLength, MessageRate)
value - Message backlog or Publish/sec. rate to trigger on.
protocol - Protocol to be used for communication. (Values: auto, http, amqp, Default: auto, Optional)
vhostName - Vhost to use for the connection, overrides any vhost set in the connection string from host/hostFromEnv. (Optional)
queueLength - DEPRECATED! Use mode: QueueLength and value: ## instead. Target value for queue length passed to the scaler. Example: if one pod can handle 10 messages, set the queue length target to 10. If the actual number of messages in the queue is 30, the scaler scales to 3 pods. Default is 20 unless publishRate is specified, in which case queueLength is disabled for this trigger.

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:

hostFromEnv - The host and port of the RabbitMQ server, similar to host, but reads it from an environment variable on the scale target.

💡 Note: host/hostFromEnv has an optional vhost name after the host slash which will be used to scope API request.

💡 Note: mode: MessageRate requires protocol http.

⚠ Important: if you have unacknowledged messages and want to have these counted for the scaling to happen, make sure to utilize the http REST API interface which allows for these to be counted.

⚠ Important: If scaling against both is desired then the ScaledObject should have two triggers, one for mode: QueueLength and the other for mode: MessageRate. HPA will scale based on the largest result considering each of the two triggers independently.

Authentication Parameters

TriggerAuthentication CRD is used to connect and authenticate to RabbitMQ:

For AMQP, the URI should look similar to amqp://guest:password@localhost:5672/vhost.
For HTTP, the URI should look similar to http://guest:password@localhost:15672/vhost.

See the RabbitMQ Ports section for more details on how to configure the ports.

Example

AMQP protocol:

apiVersion: v1
kind: Secret
metadata:
  name: keda-rabbitmq-secret
data:
  host: <AMQP URI connection string> # base64 encoded value of format amqp://guest:password@localhost:5672/vhost
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-trigger-auth-rabbitmq-conn
  namespace: default
spec:
  secretTargetRef:
    - parameter: host
      name: keda-rabbitmq-secret
      key: host
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: rabbitmq-scaledobject
  namespace: default
spec:
  scaleTargetRef:
    name: rabbitmq-deployment
  triggers:
  - type: rabbitmq
    metadata:
      protocol: amqp
      queueName: testqueue
      mode: QueueLength
      value: "20"
    authenticationRef:
      name: keda-trigger-auth-rabbitmq-conn

HTTP protocol (`QueueLength`):

apiVersion: v1
kind: Secret
metadata:
  name: keda-rabbitmq-secret
data:
  host: <HTTP API endpoint> # base64 encoded value of format http://guest:password@localhost:15672/vhost
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-trigger-auth-rabbitmq-conn
  namespace: default
spec:
  secretTargetRef:
    - parameter: host
      name: keda-rabbitmq-secret
      key: host
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: rabbitmq-scaledobject
  namespace: default
spec:
  scaleTargetRef:
    name: rabbitmq-deployment
  triggers:
  - type: rabbitmq
    metadata:
      protocol: http
      queueName: testqueue
      mode: QueueLength
      value: "20"
    authenticationRef:
      name: keda-trigger-auth-rabbitmq-conn

HTTP protocol (`MessageRate` and `QueueLength`):

apiVersion: v1
kind: Secret
metadata:
  name: keda-rabbitmq-secret
data:
  host: <HTTP API endpoint> # base64 encoded value of format http://guest:password@localhost:15672/vhost
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-trigger-auth-rabbitmq-conn
  namespace: default
spec:
  secretTargetRef:
    - parameter: host
      name: keda-rabbitmq-secret
      key: host
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: rabbitmq-scaledobject
  namespace: default
spec:
  scaleTargetRef:
    name: rabbitmq-deployment
  triggers:
  - type: rabbitmq
    metadata:
      protocol: http
      queueName: testqueue
      mode: QueueLength
      value: "20"
    authenticationRef:
      name: keda-trigger-auth-rabbitmq-conn
  - type: rabbitmq
    metadata:
      protocol: http
      queueName: testqueue
      mode: MessageRate
      value: "100"
    authenticationRef:
      name: keda-trigger-auth-rabbitmq-conn