Getting Started

This is a sample repository for creating and retrieving data for a full serverless API using Cloud Functions. Express is used for routing for the function as this is easier to maintain, control the URLs and handle requests as you do with other node.js APIs.

Setup

Install Firebase CLI & Packages

npm install -g firebase-tools

npm install firebase-functions@latest firebase-admin@latest --save

firebase login

Local Function Emulator

Setup

This is done through the CLI. You use firebase serve to run the emulator locally.

Running / Debugging Functions

See https://medium.com/@mwebler/debugging-firebase-functions-with-vs-code-3afab528bb36

Setup a local Service Key for Google Cloud. Create Service Key in json.

https://console.cloud.google.com/iam-admin/serviceaccounts?authuser=1&project=[`YOURPROJECTID`]

Docs: https://firebase.google.com/docs/functions/local-emulator

Set Local Firebase Config

Instructions for MacOS

GOOGLE_APPLICATION_CREDENTIALS="[YOUR SERVICE JSON FILE]"

FIREBASE_CONFIG="[YOUR ESCAPED JSON CONFIG STRING]"

Deleting functions from different project in emulator functions delete getStationByName --projectId devablo-197710

Debugging with VS Code

1. Run firebase function emulator with the node inspector functions inspect stations

2. Run vscode debugger 'Debug Function'

3. Set break points

4. Hit the local HTTP functions

Deploying local function for emulator

functions deploy stations --trigger-http

Removing Debugger from function functions reset stations

Running Functions

firebase serve --only functions

Deployment

firebase deploy --only functions

APIs

URL	HTTP ACTION	INFO
/api/health	GET	Sample Health Check
/api/log	POST	Logging message
/api/stations	POST	Creates a Station
/api/stations	GET	List of Stations
/api/stations/search	GET	Get Station by params (code or id)

Firebase Static Hosting for APIs

A great feature which can be used with APIs is the ability to use the static hosting by firebase which uses a CDN by default for serving content. This means with cache headers and rewriting the paths for APIs we can route it through to a function to handle the requests.

APIs available now through firebase hosting

The same end points as above

URL: https://reference-api-poc.firebaseapp.com/api/

  ,"hosting": {
    "public": "public",
    "rewrites": [ {
      "source": "/api/**", "function": "app"
    } ]
  }

Firebase Hosting Rewrite Function Handler

export const app = functions.https.onRequest(expressApp);

Firebase Functions

Firebase Console

Limited information of the functions. View the deployed functions and invocations.

https://console.firebase.google.com/u/1/project/`[YOURPROJECTID]`/functions/list

Google Cloud Functions Console

Detailed view of the functions. Can download, copy, see deployed date and analytics. You can also create new from here & test the functions.

https://console.cloud.google.com/functions/list?project=`[YOURPROJECTID]`

PubSub

PubSub Cloud Functions

The example below shows a handler for the pubsub topic stations-create and processing the message when published to the topic.

Note that the message data is base64 encoded so we need to decode it to get the real value.

exports.stationCreateSubscriberHandler = functions.pubsub.topic('stations-create').onPublish(async (message) => {
  try {
    console.info(message);
    const messageBody = message.data ? Buffer.from(message.data, 'base64').toString() : null;
    const json = { "data": messageBody }
    await firestoreService.create('log', json)
  } catch (e) {
    console.error('Error Processing Topic Message', e);
  }
});

Topic Push to HTTP Cloud Function

You have to manually go into google cloud console for PubSub and setup a new subscription for a topic. The subscription will be HTTPS and the URL will be your HTTP cloud function.

Google PubSub verifies that you own that domain. So for cloud functions you need to do a hack.

Add a endpoint which all the APIs fall under, i.e. /api/ and return meta header for that route.

It is highly recommended though that this is not the way to add subscriptions. You should use a Cloud Function with the function type pubsub where you can specify the topic for the subscription.

This repository demos this setup. See the index.ts

Publish Topic Message

Through https://console.cloud.google.com/cloudpubsub/topicList?project=reference-api-poc&authuser=1

You can publish messages and test out the Subscriptions.

HTTP Cloud Function Domain Verification

Verify through Webmaster Tools: https://www.google.com/webmasters/verification/home?hl=en&authuser=1 Then Add to Google Console Domain Verification: https://console.cloud.google.com/apis/credentials/domainverification?project=reference-api-poc&authuser=1

Example: https://us-central1-reference-api-poc.cloudfunctions.net/app/api/

Debugging

Ensure you have console logs for stdout which get picked up automatically in cloud. Adding in messages are essential for debugging cloud functions. Try and run locally to test out but last resort is to view the logs in the functions.