Lambda update function timeout

Introduction

Lambda update function timeout causes a timeout of a Lambda function, thereby updating the timeout to a specific value for a certain duration. Timeout errors interrupt the flow of the given function. Hitting a timeout is a frequent scenario with Lambda functions. This can break the service and impact the delivery. Such scenarios can occur despite the availability aids provided by AWS.

Lambda Update Function Timeout

Use cases

Lambda update function timeout:

Checks the performance of the application (or service) running with a new timeout.
Determines a safe overall timeout value for the function.

note

Kubernetes version 1.17 or later is required to execute this fault.
Access to operate AWS Lambda service.
Lambda function must be up and running.

Kubernetes secret must 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

Harness recommends using the same secret name, that is, cloud-secret. Otherwise, you must update the AWS_SHARED_CREDENTIALS_FILE environment variable in the fault template and you won't be able to use the default health check probes.
Go to superset permission/policy to execute all AWS faults.
Go to common attributes and AWS-specific tunables to tune the common tunables for all faults and AWS-specific tunables.
Go to AWS named profile for chaos to use a different profile for AWS faults.

Below is an example AWS policy to execute the fault.

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "lambda:UpdateFunctionConfiguration",
                "lambda:GetFunctionConcurrency",
                "lambda:GetFunction",
                "lambda:DeleteFunctionConcurrency",
                "lambda:PutFunctionConcurrency"
            ],
            "Resource": "*"
        }
    ]
}

Fault tunables

Mandatory tunables

Tunable	Description	Notes
FUNCTION_NAME	Function name of the target lambda function. It support single function name.	For example, `test-function`
FUNCTION_TIMEOUT	Value of function timeout in seconds.	Minimum value is 1 s and maximum is 900 s (15 minutes)
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
CHAOS_INTERVAL	The interval (in seconds) between successive instance termination.	Default: 30 s
SEQUENCE	It defines sequence of chaos execution for multiple instance	Default value: parallel. Supported: serial, parallel
RAMP_TIME	Period to wait before and after injection of chaos in seconds	For example, 30 s

Timeout value

Updates the Lambda function timeout value to a different value. Tune it by using FUNCTION_TIMEOUT environment variable.

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

# contains the timeout value for the lambda function
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: lambda-update-function-timeout
    spec:
      components:
        env:
        # provide the function timeout for 10seconds
        - name: FUNCTION_TIMEOUT
          value: '10'
        # provide the function name for timeout chaos
        - name: FUNCTION_NAME
          value: 'chaos-function'

Introduction​

Use cases​

Fault tunables​