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Lambda update function memory


Lambda update function memory causes the memory of a Lambda function to update to a specific value for a certain duration. This fault:

  • Determines a safe overall memory limit value for the function. Smaller the memory limit, higher will be the time taken by the Lambda function under load.

Lambda Update Function Memory

Use cases

Lambda update function memory:

  • Helps build resilience to unexpected scenarios such as hitting a memory limit with the Lambda function, that slows down the service and impacts its delivery. Running out of memory due to smaller limits interrupts the flow of the given function.
  • Checks the performance of the application (or service) running with a new memory limit.
  • Kubernetes version 1.17 or later is required to execute this fault.
  • Access to operate AWS Lambda functions.
  • 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
    name: cloud-secret
    type: Opaque
    cloud_config.yml: |-
    # Add the cloud AWS credentials respectively
    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 AWS named profile for chaos to use a different profile for AWS faults.
  • Go to superset permission/policy to execute all AWS faults.
  • Go to common tunables and AWS-specific tunables to tune the common tunables for all faults and AWS-specific tunables.

Below is an example AWS policy to execute the fault.

"Version": "2012-10-17",
"Statement": [
"Effect": "Allow",
"Action": [
"Resource": "*"

Fault tunables

Mandatory tunables

Tunable Description Notes
FUNCTION_NAME Function name of the target Lambda function. It supports single function name. For example, test-function
MEMORY_IN_MEGABYTES Provide the value of the memory limit of a function in megabytes. Minimum memory limit on a Lambda function is 128Mb and the maximum is 10240 Mb.
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.
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.

Memory limit

Updates the Lambda function memory limit to a different value. Tune it by using MEMORY_IN_MEGABYTES environment variable.

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

# contains the memory limit value for the lambda function
kind: ChaosEngine
name: engine-nginx
engineState: "active"
chaosServiceAccount: litmus-admin
- name: lambda-update-function-memory
# provide the function memory limit
value: '10'
# provide the function name for memory limit chaos
value: 'chaos-function'