failure-lambda
is a small Node module for injecting failure into AWS Lambda (https://aws.amazon.com/lambda). It offers a simple failure injection wrapper for your Lambda handler where you then can choose to inject failure by setting the failureMode
to latency
, exception
, blacklist
, diskspace
or statuscode
. You control your failure injection using SSM Parameter Store.
- Install
failure-lambda
module using NPM.
npm install failure-lambda
- Add the module to your Lambda function code.
const failureLambda = require('failure-lambda')
- Wrap your handler.
exports.handler = failureLambda(async (event, context) => {
...
})
- Create a parameter in SSM Parameter Store.
{"isEnabled": false, "failureMode": "latency", "rate": 1, "minLatency": 100, "maxLatency": 400, "exceptionMsg": "Exception message!", "statusCode": 404, "diskSpace": 100, "blacklist": ["s3.*.amazonaws.com", "dynamodb.*.amazonaws.com"]}
aws ssm put-parameter --region eu-west-1 --name failureLambdaConfig --type String --overwrite --value "{\"isEnabled\": false, \"failureMode\": \"latency\", \"rate\": 1, \"minLatency\": 100, \"maxLatency\": 400, \"exceptionMsg\": \"Exception message!\", \"statusCode\": 404, \"diskSpace\": 100, \"blacklist\": [\"s3.*.amazonaws.com\", \"dynamodb.*.amazonaws.com\"]}"
- Add an environment variable to your Lambda function with the key FAILURE_INJECTION_PARAM and the value set to the name of your parameter in SSM Parameter Store.
- Try it out!
Edit the values of your parameter in SSM Parameter Store to use the failure injection module.
isEnabled: true
means that failure is injected into your Lambda function.isEnabled: false
means that the failure injection module is disabled and no failure is injected.failureMode
selects which failure you want to inject. The options arelatency
,exception
,blacklist
,diskspace
orstatuscode
as explained below.rate
controls the rate of failure. 1 means that failure is injected on all invocations and 0.5 that failure is injected on about half of all invocations.minLatency
andmaxLatency
is the span of latency in milliseconds injected into your function whenfailureMode
is set tolatency
.exceptionMsg
is the message thrown with the exception created whenfailureMode
is set toexception
.statusCode
is the status code returned by your function whenfailureMode
is set tostatuscode
.diskSpace
is size in MB of the file created in tmp whenfailureMode
is set todiskspace
.blacklist
is an array of regular expressions, if a connection is made to a host matching one of the regular expressions it will be blocked.
In the subfolder example
is a simple Serverless Framework template which will install a Lambda function and a parameter in SSM Parameter Store.
npm i failure-lambda
sls deploy
Inspired by Yan Cui's articles on latency injection for AWS Lambda (https://hackernoon.com/chaos-engineering-and-aws-lambda-latency-injection-ddeb4ff8d983) and Adrian Hornsby's chaos injection library for Python (https://github.com/adhorn/aws-lambda-chaos-injection/).
- Added blacklist failure.
- Updated example application to store file in S3 and item in DynamoDB.
- Fixed issue with exception injection not throwing the exception.
- Added disk space failure.
- Updated example application to store example file in tmp.
- Initial release