Merge pull request #18 from gunnargrosch/develop

Develop

Author: gunnargrosch

README.md

@@ -2,9 +2,9 @@
 
 ## 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`, `denylist`, `diskspace` 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`, `denylist`, `diskspace` or `statuscode`. You control your failure injection using SSM Parameter Store or [AWS AppConfig](https://docs.aws.amazon.com/appconfig/latest/userguide/what-is-appconfig.html).
 
-## How to install
+## How to install with parameter in SSM Parameter Store
 
 1. Install `failure-lambda` module using NPM.
 ```bash
@@ -28,11 +28,40 @@ exports.handler = failureLambda(async (event, context) => {
 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, \"denylist\": [\"s3.*.amazonaws.com\", \"dynamodb.*.amazonaws.com\"]}"
 ```
 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!
+6. Add permissions to the parameter for your Lambda function.
+7. Try it out!
+
+## How to install with hosted configuration in AWS AppConfig
+
+1. Install `failure-lambda` module using NPM.
+```bash
+npm install failure-lambda
+```
+2. Add the module to your Lambda function code.
+```js
+const failureLambda = require('failure-lambda')
+```
+3. Wrap your handler.
+```js
+exports.handler = failureLambda(async (event, context) => {
+  ...
+})
+```
+4. Create Application, Environment, Configuration Profile, and Hosted Configuration in AppConfig console.
+5. Deploy a version of the configuration.
+6. Add the AWS AppConfig layer for Lambda extensions to your Lambda function. [See details](https://docs.aws.amazon.com/appconfig/latest/userguide/appconfig-integration-lambda-extensions.html).
+7. Add environment variables to your Lambda function.
+```bash
+FAILURE_APPCONFIG_APPLICATION: YOUR APPCONFIG APPLICATION
+FAILURE_APPCONFIG_ENVIRONMENT: YOUR APPCONFIG ENVIRONMENT
+FAILURE_APPCONFIG_CONFIGURATION: YOUR APPCONFIG CONFIGURATION PROFILE
+```
+8. Add permissions to the AppConfig Application, Environment, and Configuration Profile for your Lambda function.
+9. Try it out!
 
 ## Usage
 
-Edit the values of your parameter in SSM Parameter Store to use the failure injection module.
+Edit the values of your parameter in SSM Parameter Store or hosted configuration in AWS AppConfig 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.
@@ -58,6 +87,11 @@ Inspired by Yan Cui's articles on latency injection for AWS Lambda (https://hack
 
 ## Changelog
 
+### 2020-10-25 v0.4.0
+
+* Added optional support for AWS AppConfig, allowing to validate failure configuration, deploy configuration using gradual or non-gradual deploy strategy, monitor deployed configuration with automatical rollback if CloudWatch Alarms is configured, and caching of configuration.
+* Hardcoded default configuration with `isEnabled: false`, to use if issues loading configuration from Parameter Store or AppConfig.
+
 ### 2020-10-21 v0.3.1
 
 * Change mitm mode back to connect to fix issue with all connections being blocked.

lib/failure.js

@@ -1,26 +1,46 @@
 'use strict'
 const aws = require('aws-sdk')
 const ssm = new aws.SSM()
+const fetch = require('node-fetch')
 const childProcess = require('child_process')
 const Mitm = require('mitm')
 
-async function getConfig() {
-  try {
-    let params = {
-      Name: process.env.FAILURE_INJECTION_PARAM
+async function getConfig () {
+  const defaults = {
+    isEnabled: false
+  }
+  if (process.env.FAILURE_APPCONFIG_CONFIGURATION) {
+    try {
+      const url = 'http://localhost:2772/applications/' + process.env.FAILURE_APPCONFIG_APPLICATION + '/environments/' + process.env.FAILURE_APPCONFIG_ENVIRONMENT + '/configurations/' + process.env.FAILURE_APPCONFIG_CONFIGURATION
+      const response = await fetch(url)
+      const json = await response.json()
+      return json
+    } catch (err) {
+      console.error(err)
+      return defaults
+    }
+  } else if (process.env.FAILURE_INJECTION_PARAM) {
+    try {
+      let params = {
+        Name: process.env.FAILURE_INJECTION_PARAM
+      }
+      let response = await ssm.getParameter(params).promise()
+      let json = JSON.parse(response.Parameter.Value)
+      return json
+    } catch (err) {
+      console.error(err)
+      return defaults
     }
-    let request = await ssm.getParameter(params).promise()
-    return request.Parameter.Value
-  } catch (err) {
-    console.error(err)
-    throw err
+  } else {
+    return defaults
   }
 }
 var injectFailure = function (fn) {
   return async function () {
     try {
-      let configResponse = await getConfig()
-      let config = JSON.parse(configResponse)
+      // let configResponse = await getConfig()
+      // let config = JSON.parse(configResponse)
+      let config = await getConfig()
       if (config.isEnabled === true && Math.random() < config.rate) {
         if (config.failureMode === 'latency') {
           let latencyRange = config.maxLatency - config.minLatency

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "failure-lambda",
-  "version": "0.3.1",
+  "version": "0.4.0",
   "description": "Module for failure injection into AWS Lambda",
   "main": "./lib/failure.js",
   "scripts": {
@@ -34,6 +34,7 @@
     "eslint-plugin-standard": "^4.0.1"
   },
   "dependencies": {
-    "mitm": "^1.7.1"
+    "mitm": "^1.7.1",
+    "node-fetch": "^2.6.1"
   }
 }