Lambda update role permission

Introduction

Lambda update role permission is an AWS fault that modifies the role policies associated with a Lambda function. Sometimes, Lambda functions depend on services like RDS, DynamoDB, and S3. In such cases, certain permissions are required to access these services. This fault helps understand how your application would behave when a Lambda function does not have enough permissions to access the services.

Use cases

Lambda updated role permission:

• Verifies the handling mechanism for function failures.
• Updates the role attached to a Lambda function.
• Determines the performance of the running Lambda application when it does not have enough permissions.

note

• Kubernetes version 1.17 or later is required to execute this fault.
• The 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
• 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 the 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 when ROLE_ARN environment variable is set.

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "VisualEditor0",
            "Effect": "Allow",
            "Action": [
                "iam:PassRole",
                "lambda:GetFunction",
                "lambda:UpdateFunctionConfiguration",
                "iam:AttachRolePolicy"
            ],
            "Resource": "*"
        }
    ]
}

Below is an example AWS policy to execute the fault when POLICY_ARN environment variable is set.

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "VisualEditor0",
            "Effect": "Allow",
            "Action": [
                "iam:DetachRolePolicy",
                "lambda:GetFunction",
                "iam:ListAttachedRolePolicies",
                "iam:AttachRolePolicy",
                "iam:GetRolePolicy"
            ],
            "Resource": "*"
        }
    ]
}

Fault tunables

Mandatory tunables

Tunable	Description	Notes
FUNCTION_NAME	Name of the target Lambda function. It supports a single function name.	For example, test-function.
POLICY_ARN	Provide the policy ARN that you want to detach from the role attached
ROLE_ARN	Provide the role arn that you want to update in the lambda function	ROLE_ARN and POLICY_ARN are mutually exclusive. If both are provided, ROLE_ARN is prioritized
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 policy/role detach/update.	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.

Role ARN

Updates the role attached to a Lambda function. Tune it by using the ROLE_ARN environment variable.

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

# contains the role arn for the lambda function
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: lambda-update-role-permission
    spec:
      components:
        env:
        # provide the role arn 
        - name: ROLE_ARN
          value: 'arn:aws:iam::ACCOUNT_ID:role/service-role/chaos-role'
        # provide the function name 
        - name: FUNCTION_NAME
          value: 'chaos-function' 

Policy ARN

Detaches the policies attached to the role of Lambda function. Tune it by using the POLICY_ARN environment variable. Setting the ROLE_ARN environment variable updates the role attached to the Lambda function. Otherwise, the policy is detached using the POLICY_ARN environment variable.

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

# contains the policy arn for the lambda function
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: lambda-update-role-permission
    spec:
      components:
        env:
        # provide the policy arn 
        - name: POLICY_ARN
          value: 'arn:aws:iam::ACCOUNT_ID:policy/service-role/chaos-policy'
        # provide the function name 
        - name: FUNCTION_NAME
          value: 'chaos-function'