Trigger Specification

This specification describes the gcp-pubsub trigger for Google Cloud Platform‎ Pub/Sub.

triggers:
- type: gcp-pubsub
  metadata:
    subscriptionSize: "5" # Deprecated, use mode and value fields instead
    mode: "SubscriptionSize" # Optional - Default is SubscriptionSize - SubscriptionSize or OldestUnackedMessageAge
    value: "5" # Optional - Default is 5 for SubscriptionSize | Default is 10 for OldestUnackedMessageAge
    subscriptionName: "mysubscription" # Required
    credentialsFromEnv: GOOGLE_APPLICATION_CREDENTIALS_JSON # Required

The Google Cloud Platform‎ (GCP) Pub/Sub trigger allows you to scale based on the number of messages or oldest unacked message age in your Pub/Sub subscription.

The credentialsFromEnv property maps to the name of an environment variable in the scale target (scaleTargetRef) that contains the service account credentials (JSON). KEDA will use those to connect to Google Cloud Platform and collect the required stack driver metrics in order to read the number of messages in the Pub/Sub subscription.

subscriptionName defines the subscription that should be monitored. You can use different formulas:

• Just the subscription name, in which case you will reference a subscription from the current project or the one specified in the credentials file used.
• Use the full link provided by Google, so that you can reference a subscription that is hosted in another project Eg: projects/myproject/subscriptions/mysubscription.

You can use either subscriptionSize to define the target average which the deployment will be scaled on or mode and value fields. subscriptionSize field is deprecated, it is recommended to use mode and value fields instead. Scaler will not work if you define both subscriptionSize and at least one of mode or value. The mode chooses whether to scale using number of messages SubscriptionSize or using oldest unacked message age OldestUnackedMessageAge. The value determines the target average which the deployment will be scaled on. The default value is 5 for SubscriptionSize and 10 for OldestUnackedMessageAge.

Here’s an example.

Authentication Parameters

You can use TriggerAuthentication CRD to configure the authenticate by providing the service account credentials in JSON.

Credential based authentication:

• GoogleApplicationCredentials - Service account credentials in JSON.

Example

apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: pubsub-scaledobject
  namespace: keda-pubsub-test
spec:
  scaleTargetRef:
    name: keda-pubsub-go
  triggers:
  - type: gcp-pubsub
    metadata:
      mode: "SubscriptionSize"
      value: "5"
      subscriptionName: "mysubscription" # Required
      credentialsFromEnv: GOOGLE_APPLICATION_CREDENTIALS_JSON # Required

Example using TriggerAuthentication

apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-trigger-auth-gcp-credentials
spec:
  secretTargetRef:
  - parameter: GoogleApplicationCredentials
    name: pubsub-secret        # Required. Refers to the name of the secret
    key: GOOGLE_APPLICATION_CREDENTIALS_JSON       # Required.
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: pubsub-scaledobject
spec:
  scaleTargetRef:
    name: keda-pubsub-go
  triggers:
  - type: gcp-pubsub
    authenticationRef:
      name: keda-trigger-auth-gcp-credentials
    metadata:
      subscriptionName: "input" # Required

Identity based authentication:

You can also use TriggerAuthentication CRD to configure the authentication using the associated service account of the running machine in Google Cloud. You only need to create a TriggerAuthentication as this example, and reference it in the ScaledObject. ClusterTriggerAuthentication can also be used if you intend to use it globally in your cluster.

Example using TriggerAuthentication with GCP Identity

apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-trigger-auth-gcp-credentials
spec:
  podIdentity:
    provider: gcp
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: pubsub-scaledobject
spec:
  scaleTargetRef:
    name: keda-pubsub-go
  triggers:
  - type: gcp-pubsub
    authenticationRef:
      name: keda-trigger-auth-gcp-credentials
    metadata:
      subscriptionName: "input" # Required

Example using ClusterTriggerAuthentication with GCP Identity

apiVersion: keda.sh/v1alpha1
kind: ClusterTriggerAuthentication
metadata:
  name: keda-clustertrigger-auth-gcp-credentials
spec:
  podIdentity:
    provider: gcp
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: pubsub-scaledobject
spec:
  scaleTargetRef:
    name: keda-pubsub-go
  triggers:
  - type: gcp-pubsub
    authenticationRef:
      name: keda-clustertrigger-auth-gcp-credentials
      kind: ClusterTriggerAuthentication
    metadata:
      subscriptionName: "input" # Required