Add iam auth support

.gitignore

@@ -36,3 +36,6 @@ jspm_packages
 # Optional REPL history
 .node_repl_history
 *.zip
+
+# IntelliJ files
+.idea/

README.md

@@ -83,6 +83,25 @@ openssl enc -aes-256-cbc -d \
 -iv $(< postgres-27-12-2019@13-19-13.backup.iv)
 ```
 
+#### IAM-based Postgres authentication
+
+Your context may require that you use IAM-based authentication to log into the Postgres service.
+Support for this can be enabled my making your Cloudwatch Event look like this.
+
+```json
+
+{
+     "PGDATABASE": "dbname",
+     "PGUSER": "postgres",
+     "USE_IAM_AUTH": true,
+     "PGHOST": "host",
+     "S3_BUCKET" : "db-backups",
+     "ROOT": "hourly-backups"
+}
+```
+
+If you supply `USE_IAM_AUTH` with a value of `true`, the `PGPASSWORD` var may be omitted in the CloudWatch event.
+If you still provide it, it will be ignored.
 
 ## Developer
 

lib/config.js

@@ -5,5 +5,6 @@ module.exports = {
     S3_REGION: 'eu-west-1',
     PGDUMP_PATH: path.join(__dirname, '../bin/postgres-11.6'),
     // maximum time allowed to connect to postgres before a timeout occurs
-    PGCONNECT_TIMEOUT: 15
+    PGCONNECT_TIMEOUT: 15,
+    USE_IAM_AUTH: false
 }

lib/handler.js

@@ -1,6 +1,7 @@
 const utils = require('./utils')
 const uploadS3 = require('./upload-s3')
 const pgdump = require('./pgdump')
+const decorateWithIamToken = require('./iam')
 const encryption = require('./encryption')
 
 const DEFAULT_CONFIG = require('./config')
@@ -33,7 +34,8 @@ async function backup(config) {
 }
 
 async function handler(event) {
-    const config = { ...DEFAULT_CONFIG, ...event }
+    const baseConfig = { ...DEFAULT_CONFIG, ...event }
+    const config = event.USE_IAM_AUTH === true ? decorateWithIamToken(baseConfig) : baseConfig
     try {
         return await backup(config)
     }
@@ -46,4 +48,4 @@ async function handler(event) {
     }
 }
 
-module.exports = handler
+module.exports = handler, decorateWithIamToken

lib/iam.js

@@ -0,0 +1,14 @@
+const AWS = require('aws-sdk')
+
+function decorateWithIamToken(baseConfig) {
+    const rdsSigner = new AWS.RDS.Signer()
+    const token = rdsSigner.getAuthToken({
+        hostname: baseConfig.PGHOST,
+        port: baseConfig.PGPORT != null ? baseConfig.PGPORT : 5432,
+        region: baseConfig.S3_REGION,
+        username: baseConfig.PGUSER
+    })
+    return { ...baseConfig, PGPASSWORD: token }
+}
+
+module.exports = decorateWithIamToken

package.json

@@ -9,6 +9,7 @@
   },
   "devDependencies": {
     "aws-sdk": "2.595.0",
+    "aws-sdk-mock": "5.1.0",
     "chai": "4.2.0",
     "chai-as-promised": "7.1.1",
     "coveralls": "3.0.9",

test/.eslintrc

@@ -4,5 +4,8 @@
     "globals": {
         "describe": true,
         "it": true
+    },
+    "env": {
+        "mocha": true
     }
 }

test/handler.js

@@ -6,7 +6,10 @@ const mockDate = require('mockdate')
 const mockSpawn = require('mock-spawn')
 const chai = require('chai')
 const chaiAsPromised = require('chai-as-promised')
+const AWSMOCK = require('aws-sdk-mock')
+const AWS = require('aws-sdk')
 
+AWSMOCK.setSDKInstance(AWS)
 chai.should()
 chai.use(chaiAsPromised)
 
@@ -69,6 +72,23 @@ describe('Handler', () => {
         )
     })
 
+    it('should be able to authenticate via IAM ', async () => {
+        const { s3Spy, pgSpy } = makeMockHandler()
+
+        const iamMockEvent = { ...mockEvent, USE_IAM_AUTH: true }
+        const token = 'foo'
+        AWSMOCK.mock('RDS.Signer', 'getAuthToken', token)
+        await handler(iamMockEvent)
+        // handler should have called pgSpy with correct arguments
+        expect(pgSpy.calledOnce).to.be.true
+        expect(s3Spy.calledOnce).to.be.true
+        expect(s3Spy.firstCall.args).to.have.length(3)
+        const config = s3Spy.firstCall.args[1]
+        // production code is synchronous, so this is annoying
+        expect(await config.PGPASSWORD.promise()).to.equal(token)
+        AWSMOCK.restore('RDS')
+    })
+
     it('should upload the backup file and an iv file', async () => {
         const { s3Spy } = makeMockHandler()
 

test/iam.js

@@ -0,0 +1,41 @@
+/* eslint no-underscore-dangle: 0 */
+const { expect } = require('chai')
+const rewire = require('rewire')
+const chai = require('chai')
+const chaiAsPromised = require('chai-as-promised')
+const AWSMOCK = require('aws-sdk-mock')
+const AWS = require('aws-sdk')
+
+chai.should()
+chai.use(chaiAsPromised)
+
+AWSMOCK.setSDKInstance(AWS)
+
+
+const decorateWithIamToken = rewire('../lib/iam')
+
+describe('iam-based auth', () => {
+    it('should set the postgres default if no PGPORT is set', async () => {
+        const mockEvent = { USE_IAM_AUTH: true }
+        const token = 'foo'
+        AWSMOCK.mock('RDS.Signer', 'getAuthToken', (options) => {
+            expect(options.port).to.equal(5432)
+            return token
+        })
+        decorateWithIamToken(mockEvent)
+    })
+
+    it('should apply PGPORT to the auth-token request', async () => {
+        const mockEvent = { USE_IAM_AUTH: true, PGPORT: 2345 }
+        const token = 'foo'
+        AWSMOCK.mock('RDS.Signer', 'getAuthToken', (options) => {
+            expect(options.port).to.equal(mockEvent.PGPORT)
+            return token
+        })
+        decorateWithIamToken(mockEvent)
+    })
+
+    afterEach(() => {
+        AWSMOCK.restore('RDS.Signer')
+    })
+})