---
title: "Running a Twitter wall on the Exoscale apps PaaS"
description: "Running a Twitter wall on the Exoscale apps PaaS"
date: 2014-06-12
author: "Antoine Coetsier"
tags: ["paas","application"]
url: https://www.exoscale.com/blog/build-twitterwall-paas/
---
# Running a Twitter wall on the Exoscale apps PaaS

What to do if you are discovering PaaS? Well for sure a standard "hello world"
project is available in our
[Documentation](https://community.exoscale.com/documentation/apps/quick-start/)
but what if you are looking for something more useful?

A more compelling idea might be to display a simple web page that would fetch
tweets on a specific Twitter query. This could make a nice social
dashboard for you or your enterprise, tracking in real time mentions
of your name in Twitter.

Such apps exists in several languages. I have chosen a simple
node.js one from @cmichi on github:
[https://github.com/cmichi/twitterwall](https://github.com/cmichi/twitterwall)

## Get started

You will need a valid Exoscale account and a Twitter account (not necessarily
the one you want to monitor on your wall).

And some tools:

* GIT
* Node.js
* NPM

### Register a Twitter App

Go to the Twitter developer site at [developer.twitter.com](https://developer.twitter.com/)
and login with your account.

On your account logo, select My Applications
![twitter applications](https://www.exoscale.com/blog/build-twitterwall-paas/twitterwall-1.png)

then create a new application, and follow the form
for the name, URL, ...

Select then the API Keys tab and Generate an Access Token.
Finally take note of the following:

* API Key
* API Secret
* Access Token
* Access Token Secret

### Retrieve the code

[Download](https://github.com/retrack/twitterwall/archive/master.zip)
 the code to your laptop and unzip it.

    wget https://github.com/retrack/twitterwall/archive/master.zip

### Configure the wall

in the directory where you unzipped the code, create a file `config.js`
with the following contents:

    exports.consumer_key = 'QWERTY';
    exports.consumer_secret = 'QWERTY';
    exports.access_token_key = 'QWERTY';
    exports.access_token_secret = 'QWERTY';

Where you replace the QWERTY with the appropriate values from your Twitter App page.

In order for the PaaS to automatically launch your app when we push it
we need to tell which node file to execute. This is done via a `Procfile`
file you need to create if absent in the directory with the following contents:

    web: node server.js

more info on [Buildpacks](https://community.exoscale.com/documentation/apps/platform-documentation/#buildpacks-and-the-procfile)

Also make sure this `config.js` file is not excluded in the
`.gitignore` file. Remove the entry if found.

**Security warning:** beware not to include this file if
you push to a public git repository.

## Launch your APP

### Create an App on Exoscale Apps

Login to your [Exoscale account](https://portal.exoscale.com) and go to the
application tab.

Select create App and chose a name for your application. Select the Node.js language
and hit create.

![create PaaS app on Exoscale](https://www.exoscale.com/blog/build-twitterwall-paas/twitterwall-2.png)

### Initialize the Git repository

Follow the on screen instructions for the initialization of your git
repository

    # Create a new repository then commit, push and deploy
    git init
    git add .
    git commit -am "Initial deploy"

### Push and deploy the App

Continuing on your application root directory push and deploy
the application to Exoscale apps:

    exoapp mytwwall/default push
    exoapp mytwwall/default deploy

Back on the Exoscale portal, in the list of applications you should now see
your application deployed
![twitterwall app deployed](https://www.exoscale.com/blog/build-twitterwall-paas/twitterwall-3.png)

or just click on the Check Deploy button

![twitterwall app status](https://www.exoscale.com/blog/build-twitterwall-paas/twitterwall-4.png)

## Play with your wall

A nice blue background app should now be available for
your, capable to track via the Twitter streaming API
hashtags or usernames and display messages nicely.

![twitterwall running](https://www.exoscale.com/blog/build-twitterwall-paas/twitterwall-5.png)

### Tech notes

The app leverages the Websockets feature of Exoscale apps
note that you deactivate this with a simple config statement
like:

    exoapp mytwwall/default config.add NO_WS_SUPPORT=1

but it is less optimal for both server and browser. This
is more a way to show you how to take environment
variables in account for your application.

### EDIT: June 14th, my app crashes

Unfortunately with some success to this post, my app
crashed offering visitors a nice 502 error code.

Fortunately however, I have all necessary logs on Exoscale Apps:

![error logs](https://www.exoscale.com/blog/build-twitterwall-paas/twitterwall-6.png)

looks like it needs JS debug...