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Lambda function layer detach

Lambda function layer detach is an AWS fault that detaches the Lambda layer associated with the function, thereby causing dependency-related issues or breaking the Lambda function that relies on the layer's content.

Lambda Function Layer Detach

Use cases​

Lambda function layer detach:

  • Debug runtime errors caused by a specific library in the layer.
  • Tests how the Lambda function behaves without the dependencies provided by the layer, thereby identifying the unnecessary dependencies and reduce the layer's footprint.

Prerequisites​

  • Kubernetes >= 1.17
  • The Lambda layer must be attached to the target Lambda function.
  • Lambda function must be up and running.
  • Kubernetes secret must have the AWS access configuration (key) in the CHAOS_NAMESPACE. Below is a sample secret file: 
    apiVersion: v1
    kind: Secret
    metadata:
      name: cloud-secret
    type: Opaque
    stringData:
      cloud_config.yml: |-
        # Add the cloud AWS credentials respectively
        [default]
        aws_access_key_id = XXXXXXXXXXXXXXXXXXX
        aws_secret_access_key = XXXXXXXXXXXXXXX
tip

Harness CE recommends that you use the same secret name, that is, cloud-secret. Otherwise, you will need to update the AWS_SHARED_CREDENTIALS_FILE environment variable in the fault template with the new secret name and you won't be able to use the default health check probes.

Below is an example AWS policy to execute the fault.

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "lambda:GetFunction",
                "lambda:UpdateFunctionConfiguration",
                "lambda:DeleteLayerVersion",
                "lambda:GetLayerVersion",
                "lambda:ListLayerVersions",
            ],
            "Resource": "*"
        }
    ]
}
note

Mandatory tunables​

Tunable Description Notes
FUNCTION_NAME Name of the target Lambda function. It supports a single function name. For example, test-function.
LAMBDA_FUNCTION_LAYER_ARN Layer version that is identified by the unique ARN. Default: arn:aws:lambda:us-east-2:99999999999:layer:l-2:1,arn:aws:lambda:us-east-2:99999999999:layer:chaos_layer:1.
REGION Region name of the target Lambda function. For example, us-east-2.

Optional tunables​

Tunable Description Notes
TOTAL_CHAOS_DURATION Duration that you specify, through which chaos is injected into the target resource (in seconds). Default: 30 s. For more information, go to duration of the chaos.
AWS_SHARED_CREDENTIALS_FILE Path to the AWS secret credentials. Default: /tmp/cloud_config.yml.
CHAOS_INTERVAL Time interval between two successive deletions of reserved concurrency (in seconds). Default: 30 s. For more information, go to chaos interval.
RAMP_TIME Period to wait before and after injecting chaos (in seconds). For example, 30 s. For more information, go to ramp time.