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)
pip install chaos-lambda# function.py
import os
from chaos_lambda import inject_delay, inject_exception, inject_statuscode
# this should be set as a Lambda environment variable
os.environ['CHAOS_PARAM'] = 'chaoslambda.config'
@inject_exception
def handler_with_exception(event, context):
return {
'statusCode': 200,
'body': 'Hello from Lambda!'
}
@inject_exception(exception_type=TypeError, exception_msg='foobar')
def handler_with_exception_arg(event, context):
return {
'statusCode': 200,
'body': 'Hello from Lambda!'
}
@inject_exception(exception_type=ValueError)
def handler_with_exception_arg_2(event, context):
return {
'statusCode': 200,
'body': 'Hello from Lambda!'
}
@inject_statuscode
def handler_with_statuscode(event, context):
return {
'statusCode': 200,
'body': 'Hello from Lambda!'
}
@inject_statuscode(error_code=400)
def handler_with_statuscode_arg(event, context):
return {
'statusCode': 200,
'body': 'Hello from Lambda!'
}
@inject_delay
def handler_with_delay(event, context):
return {
'statusCode': 200,
'body': 'Hello from Lambda!'
}
@inject_delay(delay=1000)
def handler_with_delay_arg(event, context):
return {
'statusCode': 200,
'body': 'Hello from Lambda!'
}
@inject_delay(delay=0)
def handler_with_delay_zero(event, context):
return {
'statusCode': 200,
'body': 'Hello from Lambda!'
}When excecuted, the Lambda function, e.g 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 seriouslyThe 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"
}
]
}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
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