Merge pull request #2 from gunnargrosch/develop

Added disk space failure in module and example.

Author: gunnargrosch

README.md

@@ -2,7 +2,7 @@
 
 ## Description
 
-`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` or `statuscode`. You control your failure injection using SSM Parameter Store.
+`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`, `statuscode` or `diskspace`. You control your failure injection using SSM Parameter Store.
 
 ## How to install
 
@@ -22,10 +22,10 @@ exports.handler = failureLambda(async (event, context) => {
 ```
 4. Create a parameter in SSM Parameter Store.
 ```json
-{"isEnabled": false, "failureMode": "latency", "rate": 1, "minLatency": 100, "maxLatency": 400, "exceptionMsg": "Exception message!", "statusCode": 404}
+{"isEnabled": false, "failureMode": "latency", "rate": 1, "minLatency": 100, "maxLatency": 400, "exceptionMsg": "Exception message!", "statusCode": 404, "diskSpace": 100}
 ```
 ```bash
-aws ssm put-parameter --region eu-north-1 --name failureLambdaConfig --type String --overwrite --value "{\"isEnabled\": false, \"failureMode\": \"latency\", \"rate\": 1, \"minLatency\": 100, \"maxLatency\": 400, \"exceptionMsg\": \"Exception message!\", \"statusCode\": 404}"
+aws ssm put-parameter --region eu-north-1 --name failureLambdaConfig --type String --overwrite --value "{\"isEnabled\": false, \"failureMode\": \"latency\", \"rate\": 1, \"minLatency\": 100, \"maxLatency\": 400, \"exceptionMsg\": \"Exception message!\", \"statusCode\": 404, \"diskSpace\": 100}"
 ```
 5. 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.
 6. Try it out!
@@ -41,6 +41,7 @@ Edit the values of your parameter in SSM Parameter Store to use the failure inje
 * `minLatency` and `maxLatency` is the span of latency in milliseconds injected into your function when `failureMode` is set to `latency`.
 * `exceptionMsg` is the message thrown with the exception created when `failureMode` is set to `exception`.
 * `statusCode` is the status code returned by your function when `failureMode` is set to `statuscode`.
+* `diskSpace` is size in MB of the file created in tmp when `failureMode` is set to `diskspace`.
 
 ## Example
 
@@ -56,6 +57,11 @@ Inspired by Yan Cui's articles on latency injection for AWS Lambda (https://hack
 
 ## Changelog
 
+### 2019-12-30 v0.1.0
+
+* Added disk space failure.
+* Updated example application to store example file in tmp.
+
 ### 2019-12-23 v0.0.1
 
 * Initial release

example/index.js

@@ -1,9 +1,13 @@
 'use strict'
 const failureLambda = require('failure-lambda')
+const fs = require('fs')
 let response
 
 exports.handler = failureLambda(async (event, context) => {
   try {
+    fs.writeFile('/tmp/example-' + Date.now() + '.tmp', 'Contents', (err) => {
+      if (err) throw err
+    })
     response = {
       statusCode: 200,
       body: JSON.stringify({

example/package-lock.json

@@ -29,7 +29,7 @@ resources:
       Properties:
         Name: ${self:service}-${opt:stage, self:provider.stage}-failureLambdaExample
         Type: String
-        Value: '{"isEnabled": false, "failureMode": "latency", "rate": 1, "minLatency": 100, "maxLatency": 400, "exceptionMsg": "Exception message!", "statusCode": 404}'
+        Value: '{"isEnabled": false, "failureMode": "latency", "rate": 1, "minLatency": 100, "maxLatency": 400, "exceptionMsg": "Exception message!", "statusCode": 404, "diskSpace": 100}'
 package:
   exclude:
     - .vscode

example/serverless.yml

@@ -1,6 +1,7 @@
 'use strict'
 const aws = require('aws-sdk')
 const ssm = new aws.SSM()
+const childProcess = require('child_process')
 
 async function getConfig () {
   try {
@@ -32,6 +33,9 @@ var injectFailure = function (fn) {
           console.log('Injecting status code: ' + config.statusCode)
           let response = { statusCode: config.statusCode }
           return response
+        } else if (config.failureMode === 'diskspace') {
+          console.log('Injecting disk space: ' + config.diskSpace + ' MB')
+          childProcess.spawnSync('dd', ['if=/dev/zero', 'of=/tmp/diskspace-failure-' + Date.now() + '.tmp', 'count=1000', 'bs=' + config.diskSpace * 1000])
         }
       }
       return fn.apply(this, arguments)

lib/failure.js

@@ -1,6 +1,6 @@
 {
   "name": "failure-lambda",
-  "version": "0.0.1",
+  "version": "0.1.0",
   "description": "Module for failure injection into AWS Lambda",
   "main": "./lib/failure.js",
   "scripts": {