Lambda delete event source mapping

Lambda delete event source mapping removes the event source mapping from an AWS Lambda function for a specific duration. Deleting an event source mapping from a Lambda function is critical. It can lead to failure in updating the database on an event trigger, which can break the service.

Use cases

Lambda delete event source mapping:

• Determines the performance of the application (or service) without the event source mapping that may cause missing entries in a database.
• Determines whether proper error handling or auto-recovery options have been configured for the application.

Prerequisites

• Kubernetes >= 1.17
• AWS Lambda event source mapping must be healthy and attached to the Lambda function.
• Kubernetes secret should have the AWS access configuration(key) in the CHAOS_NAMESPACE. A secret file looks like this:

  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

HCE 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:ListEventSourceMappings",
                "lambda:DeleteEventSourceMapping",
                "lambda:UpdateEventSourceMapping",
                "lambda:CreateEventSourceMapping",
                "lambda:UpdateFunctionConfiguration",
                "lambda:GetFunctionConcurrency",
                "lambda:GetFunction",
                "lambda:DeleteFunctionConcurrency",
                "lambda:PutFunctionConcurrency"
            ],
            "Resource": "*"
        }
    ]
}

note

• Refer to AWS named profile for chaos to use a different profile for AWS faults.
• Refer to the superset permission/policy to execute all AWS faults.
• Refer to the common tunables and AWS-specific tunables to tune the common tunables for all faults and AWS-specific tunables.

Mandatory tunables

Tunable	Description	Notes
FUNCTION_NAME	Function name of the target Lambda function. Supports single function name.	For example, test-function
EVENT_UUIDS	Provide the UUID for the target event source mapping.	Can provide multiple values as comma-separated values. For example, id1,id2
REGION	The 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.
SEQUENCE	It defines sequence of chaos execution for multiple instance	Default: parallel. Supports serial and parallel. For more information, go to sequence of chaos execution.
RAMP_TIME	Period to wait before and after injection of chaos (in seconds).	For example, 30 s. For more information, go to ramp time.

Multiple event source mapping

Deletes multiple event source mappings for a specific duration using EVENT_UUIDS environment variable. This variable takes the UUID of the events as a comma-separated value.

The following YAML snippet illustrates the use of this environment variable:

# contains the removal of multiple event source mapping
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: lambda-delete-event-source-mapping
    spec:
      components:
        env:
        # provide UUIDS of event source mapping
        - name: EVENT_UUIDS
          value: 'id1,id2'
        # provide the function name for the chaos
        - name: FUNCTION_NAME
          value: 'chaos-function'