Trigger Specification

This specification describes the aws-cloudwatch trigger that scales based on a AWS CloudWatch.

triggers:
- type: aws-cloudwatch
  metadata:
    # Required: namespace
    namespace: AWS/SQS
    # Optional: Dimension Name
    dimensionName: QueueName
    # Optional: Dimension Value
    dimensionValue: keda
    # Optional: Expression query
    expression: SELECT MAX("ApproximateNumberOfMessagesVisible") FROM "AWS/SQS" WHERE QueueName = 'keda'
    metricName: ApproximateNumberOfMessagesVisible
    targetMetricValue: "2.1"
    minMetricValue: "1.5"
    # Required: region
    awsRegion: "eu-west-1"
    # Optional: AWS endpoint url
    awsEndpoint: ""
    # Optional: AWS Access Key ID, can use TriggerAuthentication as well
    awsAccessKeyIDFromEnv: AWS_ACCESS_KEY_ID # default AWS_ACCESS_KEY_ID
    # Optional: AWS Secret Access Key, can use TriggerAuthentication as well
    awsSecretAccessKeyFromEnv: AWS_SECRET_ACCESS_KEY # default AWS_SECRET_ACCESS_KEY
    identityOwner: pod | operator # Optional. Default: pod
    # Optional: Collection Time
    metricCollectionTime: "300" # default 300
    # Optional: Metric Statistic
    metricStat: "Average" # default "Average"
    # Optional: Metric Statistic Period
    metricStatPeriod: "300" # default 300
    # Optional: Metric Unit
    metricUnit: "Count" # default ""
    # Optional: Metric EndTime Offset
    metricEndTimeOffset: "60" # default 0

Parameter list:

• awsRegion - AWS Region for the AWS Cloudwatch.

• awsEndpoint - Endpoint URL to override the default AWS endpoint. (Default: "", Optional)

• dimensionName - Supports specifying multiple dimension names by using “;” as a separator i.e. dimensionName: QueueName;QueueName (Optional, Required when expression is not specified)

• dimensionValue - Supports specifying multiple dimension values by using “;” as a separator i.e. dimensionValue: queue1;queue2 (Optional, Required when expression is not specified)

• expression - Supports query with expression (Optional, Required when dimensionName & dimensionValue are not specified)

• identityOwner - Receive permissions for CloudWatch via Pod Identity or from the KEDA operator itself (see below). (Values: pod, operator, Default: pod, Optional)

When identityOwner set to operator - the only requirement is that the KEDA operator has the correct IAM permissions on the CloudWatch. Additional Authentication Parameters are not required.

• metricCollectionTime - How long in the past (seconds) should the scaler check AWS Cloudwatch. Used to define StartTime (official documentation). The value of metricCollectionTime must be greater than the metricStatPeriod, providing a value which is a multiple of the metricStatPeriod can improve performance on fetching data from Cloudwatch. In practice setting metricCollectionTime 2-to-3 times more than the metricStatPeriod value can make sure the scaler is able to get data points back from Cloudwatch, the scaler will always use the most up-to-date datapoint if more datapoints are returned. (Default: 300, Optional)
• metricStat - Which statistics metric to be used by the query. Used to define Stat (official documentation). (Default: Average, Optional)
• metricStatPeriod - Which frequency to be used by the related query. Used to define Period. The value cannot be an arbitrary number, it must be a value supported by Cloudwatch (1, 5, 10, 30, or a multiple of 60). More details can be found from (official documentation). (Default: 300, Optional)
• metricUnit - Which unit to be used by the query. Used to define Unit (official documentation). (Default: none, Optional)
• metricEndTimeOffset - How long in seconds to offset the EndTime (official documentation). Due to the eventual consistency model which is used by Cloudwatch, the latest datapoint one can get from Cloudwatch might not be accurate. The metricEndTimeOffset config provides a way to skip the most recent datapoint if needed. (Default: 0, Optional)
• minMetricValue- Returned value in case of empty response from cloudwatch. (Default: 0, This value can be a float)
• targetMetricValue- Target value for the metric. (Default: 0, This value can be a float)
• activationTargetMetricValue- Target value for activating the scaler. Learn more about activation here.(Default: 0, Optional, This value can be a float)

Authentication Parameters

These parameters are relevant only when identityOwner is set to pod.

You can use TriggerAuthentication CRD to configure authentication by providing either a role ARN or a set of IAM credentials.

Pod identity based authentication:

• podIdentity.provider - Needs to be set to either aws-kiam or aws-eks on the TriggerAuthentication and the pod/service account must be configured correctly for your pod identity provider.

Role based authentication:

• awsRoleArn - Amazon Resource Names (ARNs) uniquely identify AWS resource.

Credential based authentication:

• awsAccessKeyID - Id of the user.
• awsSecretAccessKey - Access key for the user to authenticate with.
• awsSessionToken - Session token, only required when using temporary credentials.

The user will need access to read data from AWS CloudWatch.

IAM Permissions

The user or role used to authenticate with AWS CloudWatch must have the cloudwatch:GetMetricData permissions. The following is an example IAM policy that grants the necessary permissions to read data from CloudWatch:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "AllowCloudWatchGetMetricData",
      "Effect": "Allow",
      "Action": "cloudwatch:GetMetricData",
      "Resource": "*"
    }
  ]
}

This can be further scoped to specific namespaces, by using the cloudwatch:namespace condition key. For example, to only allow access to the AWS/EC2 metric namespace:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "AllowCloudWatchGetMetricData",
      "Effect": "Allow",
      "Action": "cloudwatch:GetMetricData",
      "Resource": "*",
      "Condition": {
        "StringEquals": {
          "cloudwatch:namespace": "AWS/EC2"
        }
      }
    }
  ]
}

For more information, see the AWS CloudWatch IAM documentation.

Example

apiVersion: v1
kind: Secret
metadata:
  name: test-secrets
data:
  AWS_ACCESS_KEY_ID: <encoded-user-id> # Required.
  AWS_SECRET_ACCESS_KEY: <encoded-key> # Required.
  AWS_SESSION_TOKEN: <encoded-session-token> # Required when using temporary credentials.
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-trigger-auth-aws-credentials
  namespace: keda-test
spec:
  secretTargetRef:
  - parameter: awsAccessKeyID     # Required.
    name: test-secrets            # Required.
    key: AWS_ACCESS_KEY_ID        # Required.
  - parameter: awsSecretAccessKey # Required.
    name: test-secrets            # Required.
    key: AWS_SECRET_ACCESS_KEY    # Required.
  - parameter: awsSessionToken    # Required when using temporary credentials.
    name: test-secrets            # Required when using temporary credentials.
    key: AWS_SESSION_TOKEN        # Required when using temporary credentials.
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: aws-cloudwatch-queue-scaledobject
  namespace: keda-test
spec:
  scaleTargetRef:
    name: nginx-deployment
  triggers:
  - type: aws-cloudwatch
    metadata:
      namespace: AWS/SQS
      dimensionName: QueueName
      dimensionValue: keda
      metricName: ApproximateNumberOfMessagesVisible
      targetMetricValue: "2.1"
      minMetricValue: "0"
      awsRegion: "eu-west-1"
    authenticationRef:
      name: keda-trigger-auth-aws-credentials