Decorators and Class to inject failures into AWS Lambda functions
Project description
chaos_lambda is a small library injecting chaos into AWS Lambda. It offers simple python decorators to do delay, exception and statusCode injection and a Class to add delay to any 3rd party dependencies called from your function. This allows to conduct small chaos engineering experiments for your serverless application in the AWS Cloud.
Support for Latency injection using delay
Support for Exception injection using exception_msg
Support for HTTP Error status code injection using error_code
Using for SSM Parameter Store to control the experiment using isEnabled
Support for adding rate of failure using rate. (Default rate = 1)
Per Lambda function injection control using Environment variable (CHAOS_PARAM)
Install
pip install chaos-lambda
Example
# function.py
from chaos_lambda import (
inject_delay, inject_exception, inject_statuscode)
os.environ['CHAOS_PARAM'] = 'chaoslambda.config'
@inject_exception
def lambda_handler_with_exception(event, context):
return {
'statusCode': 200,
'body': 'Hello from Lambda!'
}
@inject_delay
def lambda_handler_with_delay(event, context):
return {
'statusCode': 200,
'body': 'Hello from Lambda!'
}
@inject_statuscode
def lambda_handler_with_statuscode(event, context):
return {
'statusCode': 200,
'body': 'Hello from Lambda!'
}
When excecuted, the Lambda function, e.g lambda_handler_with_exception('foo', 'bar'), will produce the following result:
exception_msg from config I really failed seriously with a rate of 1
corrupting now
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/.../chaos_lambda.py", line 199, in wrapper
raise Exception(exception_msg)
Exception: I really failed seriously
Configuration
The configuration for the failure injection is stored in the AWS SSM Parameter Store and accessed at runtime by the get_config() function:
{
"isEnabled": true,
"delay": 400,
"error_code": 404,
"exception_msg": "I really failed seriously",
"rate": 1
}
To store the above configuration into SSM using the AWS CLI do the following:
aws ssm put-parameter --region eu-north-1 --name chaoslambda.config --type String --overwrite --value "{ "delay": 400, "isEnabled": true, "error_code": 404, "exception_msg": "I really failed seriously", "rate": 1 }"
AWS Lambda will need to have IAM access to SSM.
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"ssm:DescribeParameters"
],
"Resource": "*"
},
{
"Effect": "Allow",
"Action": [
"ssm:GetParameters",
"ssm:GetParameter"
],
"Resource": "arn:aws:ssm:eu-north-1:12345678910:parameter/chaoslambda.config"
}
]
}
Supported Decorators:
chaos_lambda currently supports the following decorators:
@inject_delay - add delay in the AWS Lambda execution
@inject_exception - Raise an exception during the AWS Lambda execution
@inject_statuscode - force AWS Lambda to return a specific HTTP error code
and the following class:
SessionWithDelay - enabled to sub-classing requests library and call dependencies with delay
More information:
Project details
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