2013-08-24

Deploy your nodeJS/Express app to AppFog Paas

AppFog is a cloud based "platform as a service" (PaaS) that let you run your web applications, even on private clouds.
It supports different technologies and offers a lot of installable plugins or services. Therefore no matters if you have to deploy a Python, Django, Java, NodeJS, PHP app based on MongoDB, MySQL, Redis and so on.

Appfog does not force you to change your devel habits: you can develop locally your app as usual and then deploy it with just one command as we will see. The main philosophy is: "work on code, not management".

At this time appfog supports the following versions:
  • Python (2.7.3)
  • NodeJS (0.8.14, 0.6.17, 0.4.12)
  • PHP (5.3.10)
  • Ruby (1.8.7, 1.9.3, 1.9.2)
  • Java (1.7.0)
You can choose the supported environment you prefer. Obviously for the most reliable development experience, make sure you have the same version on your local development environment.

Can't wait for trying AppFog?

Here it is the basic getting started playing with the console offline:
  1. sign up to http://console.appfog.com/signup 
  2. install the appfog af command line interface https://docs.appfog.com/getting-started/af-cli 
Now you can play as well with the AppFog console online as shown here https://docs.appfog.com/getting-started/jumpstarts but I suggest to have a look at the command line syntax.

All you need to know is covered in the docs area https://docs.appfog.com but we we'll see the most useful commands right now.

In the next sections we will consider a NodeJS / Express app as example, so let's start with NodeJS, Express and AppFog now.

NodeJS installation

Talking about NodeJS, you might use the Node Version Manager (NVM) to manage multiple Node.js versions as described in this article http://codetheory.in/using-node-version-manager-nvm-to-manage-multiple-node-js-versions/. Installing the right version of NodeJS is as simple as typing the command:
$ nvm install NODE_VERSION (for example: 0.8.14)

Create your app NodeJS/Express app

Now you can develop locally your app as usual with Node and Express.
If you want to create a hello world application you can start using the express executable or starting from scratch. Both of the above options are described in this guide http://expressjs.com/guide.html

Or if you prefer you can start with an app generated by one of the available yeoman's generators. You can see the full list of the yeoman's community generators: http://yeoman.io/community-generators.html.
You can use a specific yeoman's express generator or choosing another one that fits better your needs and then add the Express dependency by hand. For this post I'll use as reference the hello world app based on Yeoman/Node/Express/AngularJS/generator-angular shown in this previous post:
Once created your NodeJS/Express app as usual you need to perform some small changes.

Make your app compatible with AppFog

It's quite simple.

Firstly make sure you have provided the start command under the scripts key in your package.json file, for example:
  "scripts": {
    "test": "grunt test",
    "start": "node app.js"
  }
If you don't provide the start command AppFog runs the first of the following files it finds:
  • server.js
  • app.js
  • index.js
  • main.js
  • application.js
After that you need to change the listen port of your app: AppFog passes the listen port for your app in an environment variable, accessed by process.env.VCAP_APP_PORT. So depending on how it is organized your app.js, you need to change the listend port:
-app.set('port', process.env.PORT || 3000);
+app.set('port', process.env.VCAP_APP_PORT || 3000);
AppFog requires also a manifest file named manifest.yml, but don't worry: the first time you push your app there will be an interactive prompt as you will see in the next section.

Now you are ready to deploy your app to AppFog.

Deploy your app to AppFog

Since AppFog supports npm shrinkwrap (see https://npmjs.org/doc/shrinkwrap.html for more details), before pushing your app you might want to lock down the versions of your package's dependencies: this way you can control exactly which versions of each dependency will be used when your package is installed in the AppFog cloud.

It requires you just one command:
$ npm shrinkwrap
wrote npm-shrinkwrap.json
Now we are close to pushing our app. Basically you have to login using the credentials typed during the sign up process. It is very simple as you can see:
$ af login
Attempting login to [https://api.appfog.com]
Email: YOUREMAIL
Password: *********************
Successfully logged into [https://api.appfog.com]
Type the push command with the interactive prompt:
$ af push
Would you like to deploy from the current directory? [Yn]: Y
Application Name: YOURAPP
Detected a Node.js Application, is this correct? [Yn]: Y
1: AWS US East - Virginia
2: AWS EU West - Ireland
3: AWS Asia SE - Singapore
4: HP AZ 2 - Las Vegas
Select Infrastructure: 2
Application Deployed URL [YOURAPP.eu01.aws.af.cm]:
Memory reservation (128M, 256M, 512M, 1G, 2G) [64M]:
How many instances? [1]:
Create services to bind to 'YOURAPP'? [yN]: N
Would you like to save this configuration? [yN]: y
Manifest written to manifest.yml.
Creating Application: OK
Uploading Application:
  Checking for available resources: OK
  Processing resources: OK
  Packing application: OK
  Uploading (800K): OK 
Push Status: OK
Staging Application 'YOURAPP': OK                                         
Starting Application 'YOURAPP': OK
The generated manifest.yml file is similar to the following:
$ cat manifest.yml
---
applications:
  .:
    mem: 64M
    framework:
      info:
        description: NodeJS, Express, AngularJS Application
        exec:
        mem: 64M
      name: node
    instances: 1
    url: ${name}.${target-base}
    infra: eu-aws
    name: YOURAPP
If you need to do some future changes you should run the af update command instead.

Done, your app is online at http://YOURAPP.eu01.aws.af.cm!

If you have some tips or suggestions let me know please.

Additional notes

Errors during push or upload

Sometimes you may experiment this error trying to update or pushing your app:

HTTP exception: RestClient::ServerBrokeConnection:Server broke connection:
After a quick search on the net it seems a recurring problem and, if it happens, it may persist for a lot of hours or several days. Probably it is due to overload issues. I don't think it's related to a code problem because sometimes it works.

Fortunately it was only an annoying problem in my case because it was just a hello world app but... you can image if you are in a hurry and you have to update your business app what a problem!

AppFog guys, please let me know if I'm doing something of wrong!

Anyway if you experiment similar problems see https://www.appfog.com/support/

Update 20130825: the problem seems to be fixed for me using the --no-resource option (for example: af update --no-resource). This option is not listed at all in the af --help command. Now the update command works fine, good! Hope it might help other people this experience.
If you have other troubles you can visit the Node section of AppFog troubleshooting page https://docs.appfog.com/troubleshooting

Environment vars

You must notice that AppFog supports environment vars.

These will be accessible to your app at runtime. You can specify data that you do not want in your source code like passwords, API keys, or differentiate between staging and production environments.

Since also Express supports arbitrary environments, like production and development, you can use the configure method to set different configurations under the different environments.

For example in production mode you may use images, css and js minified, disabling devel settings, etc.

You can add environment vars through the web using the console online or via command line:
$ af env-add YOURAPP status=production
Adding Environment Variable [status=production]: OK
Stopping Application 'YOURAPP': OK
Staging Application 'YOURAPP': OK                                      
Starting Application 'YOURAPP': OK 
Update 20130825: you can get your env app with process.env.YOURENVVAR.
  

Quickstart

If you are not familiar with Node, Express, yeoman&co and you want to have a try, you can start from this hello world I presented in this previous post:
You should perform these actions:
  1. git clone git@github.com:davidemoro/express-angular.git
  2. $ cd express-angular
  3. change your manifest.yml and other files that reference the old app name (grep is your friend)
  4. $ npm install
  5. $ bower install
  6. $ af login
  7. $ af push
If you want to enable the production mode you should type:
  1. $ grunt build
  2. $ af update
  3. $ af env-add YOURAPP status=production
Let me know if you find some problems.

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