Added aws-node-heroku-postgres example.

README.md

@@ -60,6 +60,7 @@ serverless install -u https://github.com/serverless/examples/tree/master/folder-
 | [Serverless Github Check](https://github.com/serverless/examples/tree/master/aws-node-github-check)  | nodeJS |
 | [Aws Github Webhook Listener](https://github.com/serverless/examples/tree/master/aws-node-github-webhook-listener) <br/> Extend your github repositories with this github webhook listener | nodeJS |
 | [Aws Node Graphql Api With Dynamodb](https://github.com/serverless/examples/tree/master/aws-node-graphql-api-with-dynamodb) <br/> A single-module GraphQL endpoint with query and mutation functionality. | nodeJS |
+| [Aws Lambda And Heroku Postgres](https://github.com/serverless/examples/tree/master/aws-node-heroku-postgres) <br/> Shows how to connect AWS Lambda to Heroku Postgres. Uses an api:release Heroku webhook and the Heroku API to handle automatic Heroku Postgres credential rotation. | nodeJS |
 | [Aws Iot Event](https://github.com/serverless/examples/tree/master/aws-node-iot-event) <br/> Example on how to setup a AWS IoT Rule to send events to a Lambda function | nodeJS |
 | [Dropbox](https://github.com/serverless/examples/tree/master/aws-node-oauth-dropbox-api) <br/> dropbox integration | nodeJS |
 | [Aws Node Puppeteer](https://github.com/serverless/examples/tree/master/aws-node-puppeteer) <br/> When it comes to AWS Lambda function , they have their own limits as follows ![AWS Limits](./images/aws_limits.png) So , When you try to use Puppeteer your deployment package size(unzipped)  easily go's above 250 mb because When you install Puppeteer, it downloads a recent version of Chromium (~170MB Mac, ~282MB Linux, ~280MB Win) that is guaranteed to work with the API. | nodeJS |

aws-node-heroku-postgres/.gitignore

@@ -0,0 +1,6 @@
+# package directories
+node_modules
+jspm_packages
+
+# Serverless directories
+.serverless

aws-node-heroku-postgres/README.md

@@ -0,0 +1,14 @@
+<!--
+title: 'Node.js AWS Lambda connecting to Heroku Postgres'
+description: 'Shows how to connect AWS Lambda to Heroku Postgres. Uses an api:release Heroku webhook and the Heroku API to handle automatic Heroku Postgres credential rotation.'
+layout: Doc
+framework: v1
+platform: AWS
+language: nodeJS
+authorLink: 'https://github.com/welkie'
+authorName: 'Matt Welke'
+authorAvatar: 'https://avatars0.githubusercontent.com/u/7719209'
+-->
+# aws-node-heroku-postgres
+
+An example app, created in this [blog post](https://mattwelke.com/2019/01/06/free-tier-managed-sql-with-aws-lambda-and-heroku-postgres.html), showing how to connect AWS Lambda to Heroku Postgres. Uses an `api:release` Heroku webhook and the Heroku API to handle automatic Heroku Postgres credential rotation.

aws-node-heroku-postgres/handler.js

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+// handler.js
+'use strict';
+
+const express = require('express');
+const serverless = require('serverless-http');
+const pg = require('pg');
+const axios = require('axios');
+const parsePgConnStr = require('pg-connection-string').parse;
+
+// Replace with your token or API key and your Heroku Postgres resource name
+const herokuApiKey = '';
+const herokuPostgresId = '';
+const herokuClient = axios.create({
+    baseURL: 'https://api.heroku.com/',
+    headers: {
+        'Authorization': `Bearer ${herokuApiKey}`,
+        'Accept': 'application/vnd.heroku+json; version=3',
+    },
+});
+
+let pgConfig;
+let pgPool;
+
+const app = express();
+
+const createConn = async () => {
+    console.log('Creating PG connection.');
+
+    const credsResponse = await herokuClient.get(`addons/${herokuPostgresId}/config`);
+    const pgConnStr = credsResponse.data[0]['value'];
+
+    pgConfig = {
+        ...parsePgConnStr(pgConnStr), ...{
+            max: 1,
+            ssl: true,
+        },
+    };
+
+    pgPool = new pg.Pool(pgConfig);
+};
+
+const performQuery = async () => {
+    const client = await pgPool.connect();
+    const result = await client.query('SELECT now()');
+    client.release();
+    return result;
+};
+
+app.get('/hello', async function (req, res) {
+    if (!pgPool) {
+        // Cold start. Get Heroku Postgres creds and create pool.
+        await createConn();
+    } else {
+        console.log('Using existing PG connection.');
+    }
+
+    try {
+        const result = await performQuery();
+
+        res.json({
+            result: `According to PostgreSQL, the time is: ${result.rows[0].now}`,
+            pgConfigUsed: pgConfig,
+        });
+        return;
+    } catch (e) {
+        res.json({
+            error: e.message,
+        });
+        return;
+    }
+
+});
+
+app.post('/onrelease', async function (req, res) {
+    // Get Heroku Postgres creds and replace pool with new one.
+    await createConn();
+
+    // Response with 2xx response so Heroku knows webhook was successful.
+    // Response body doesn't matter.
+    res.status(204).send();
+});
+
+module.exports = {
+    app,
+    hello: serverless(app),
+};

aws-node-heroku-postgres/index.js

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+// index.js
+'use strict';
+
+const { app } = require('./handler');
+
+app.listen(3000, () => {
+    console.info(`Listening on port 3000.`);
+});