Getting started with Wercker & Javascript

This guide is a step-by-step approach to developing, building and deploying a sample app with wercker within minutes.

While this guide uses javascript, the general concepts explained in this tutorial apply to every other programming language.


To be able to follow along with this guide, you will need the following things:

Setting up the app

Before we can start developing, we have to fork and clone the sample app into our local development environment. After you’ve done that, cd into the project directory.

$ cd getting-started-nodejs/

Developing the app

Now that we’ve setup our app we can start developing. Our list of cities is a bit short, so why not add another one in there? Before we do that however, let’s first take a closer look at the wercker.yml file included in your project folder.


The wercker.yml is the only config file you need for using wercker. In it, you will define all your steps needed to successfully develop, build and deploy your application.

To get started however, we’re only interested in developing our app, so let’s take a closer look at this dev pipeline right now.

Dev pipeline

# The container definition we want to use for developing our app
box: node:4.2.6-slim
# Defining the dev pipeline
    - npm-install
    - internal/watch:
        code: node app.js
        reload: true

The first line specifies which container image you want to use for your project. Since we’re developing with nodejs, we’ve already specified an image for you. These container images are retrieved from Docker Hub if no other registry is specified. You can read more about containers here.

In the dev clause we define what we want to happen in our development pipeline, which in this case consists of two steps: npm-install and internal/watch.

These steps are pre-written bash scripts written by either wercker or the community. You can read more about steps here

npm-install is a wercker step that, unsurprisingly, runs npm-install.

internal/watch watches your files for changes, and if reload is set to true it restarts your app so your changes are reflected immediately. This is especially useful for when you’re developing webapps, as we’re doing now.

Let’s see these steps in action now and fire up our dev pipeline.

wercker dev

In your project folder, run wercker dev --publish 5000. You should see something similar to the following output:

--> Executing pipeline
--> Running step: setup environment
Pulling repository nodesource/trusty
Pulling image (latest) from nodesource/trusty: 1a464bde82b1
Pulling image (latest) from nodesource/trusty, endpoint: 1a464bde82b1
Pulling dependent layers: 1a464bde82b1
Pulling fs layer: bfe5eacf5a79
Download complete: bfe5eacf5a79
Pulling metadata: 1a464bde82b1
Pulling fs layer: 1a464bde82b1
Download complete: 1a464bde82b1
Download complete: 1a464bde82b1
Status: Downloaded newer image for nodesource/trusty:latest
--> Running step: wercker-init
--> Running step: npm-install
Starting npm install, try: 1
npm WARN package.json getting-started-nodejs@0.0.1 No repository field.
npm WARN package.json supertest@0.4.0 No repository field.
Finished npm install
--> Running step: watch
--> Reloading on file changes
--> Reloading
--> Forwarding to 5000 on the container.

Wercker first checks out your code and then sets up the container environment. This means that the container will be pulled from Docker Hub and subsequently started with access to your checked out code. It will then start executing all the steps that are defined in the wercker.yml.

Please note that the IP displayed here could be different for you, as this tutorial was written using boot2docker.

If you navigate to DOCKER_HOST_IP:5000 you should see the same output as before. That’s not very exciting, so let’s see our live reloading in action. In app.js add a new city to the array:

app.get('/', function(req, res){
    res.writeHead(200, { 'Content-Type': 'application/json' });
    res.write(JSON.stringify({cities : ["San Francisco","Amsterdam", "Berlin", "New York", "Palo Alto", "San Mateo", "Paris"]}));

Once you save your changes, the app should automatically reload. If you refresh your page, our new city should be there! Hurrah!

There are many more steps to use for developing your app. Take a look around, and if you can’t find the step you’re looking for, you can always make your own.

Now that we’re done developing, we want to push our changes and let wercker build and deploy our app for us.

Building your app

First, let’s revisit our wercker.yml again.

box: node:4.2.6-slim
    - npm-install
    - internal/watch:
        code: node app.js
        reload: true

# Build definition
  # The steps that will be executed on build
    - script:
        code: export NODE_ENV='testing'
    # A step that executes `npm install` command
    - npm-install
    # A step that executes `npm test` command
    - npm-test

    # A custom script step, name value is used in the UI
    # and the code value contains the command that get executed
    - script:
        name: echo nodejs information
        code: |
          echo "node version $(node -v) running"
          echo "npm version $(npm -v) running"

Build Pipeline

We’re now interested in what’s happening the build pipeline, where we’ve added a new kind of step: a script step. This script step is a piece of inline bash code which we’re using to run our tests. You can create and share these kind of steps with the community by submitting a step to our repository.

wercker build

Now that we have a better understanding of our wercker.yml let’s go ahead and let wercker build our project. In your project folder, first run rm -r node_modules, and then wercker build:

$ wercker build
--> Executing pipeline
--> Running step: setup environment
Pulling repository nodesource/trusty
Pulling image (latest) from nodesource/trusty: 1a464bde82b1
Pulling image (latest) from nodesource/trusty, endpoint: 1a464bde82b1
Pulling dependent layers: 1a464bde82b1
Download complete: 428b411c28f0
Download complete: bfe5eacf5a79
Download complete: 1a464bde82b1
Download complete: 1a464bde82b1
Status: Image is up to date for nodesource/trusty:latest
--> Running step: wercker-init
--> Running step: script
--> Running step: npm-install
Starting npm install, try: 1
npm WARN package.json getting-started-nodejs@0.0.1 No repository field.
supertest@0.4.0 node_modules/supertest
├── methods@0.0.1
└── superagent@0.9.5 (cookiejar@1.3.0, emitter-component@0.0.5, qs@0.4.2, mime@1.2.5, formidable@1.0.9)

mocha@1.6.0 node_modules/mocha
├── growl@1.5.1
├── commander@0.6.1
├── diff@1.0.2
├── mkdirp@0.3.3
├── debug@2.2.0 (ms@0.7.1)
├── ms@0.3.0
└── jade@0.26.3 (mkdirp@0.3.0)

express@3.21.0 node_modules/express
├── escape-html@1.0.2
├── merge-descriptors@1.0.0
├── cookie@0.1.3
├── utils-merge@1.0.0
├── cookie-signature@1.0.6
├── methods@1.1.1
├── fresh@0.3.0
├── basic-auth@1.0.2
├── range-parser@1.0.2
├── content-type@1.0.1
├── etag@1.7.0
├── vary@1.0.0
├── parseurl@1.3.0
├── content-disposition@0.5.0
├── commander@2.6.0
├── depd@1.0.1
├── debug@2.2.0 (ms@0.7.1)
├── proxy-addr@1.0.8 (forwarded@0.1.0, ipaddr.js@1.0.1)
├── mkdirp@0.5.1 (minimist@0.0.8)
├── send@0.13.0 (destroy@1.0.3, ms@0.7.1, statuses@1.2.1, mime@1.3.4, http-errors@1.3.1, on-finished@2.3.0)
└── connect@2.30.0 (bytes@2.1.0, pause@0.0.1, vhost@3.0.0, on-headers@1.0.0, basic-auth-connect@1.0.0, response-time@2.3.1, method-override@2.3.3, cookie-parser@1.3.5, serve-static@1.10.0, http-errors@1.3.1, connect-timeout@1.6.2, qs@2.4.2, serve-favicon@2.3.0, morgan@1.6.0, finalhandler@0.4.0, multiparty@3.3.2, csurf@1.8.3, express-session@1.11.3, body-parser@1.13.1, errorhandler@1.4.0, serve-index@1.7.0, type-is@1.6.3, compression@1.5.0)

nodeunit@0.7.4 node_modules/nodeunit
└── tap@1.2.0 (opener@1.4.1, foreground-child@1.2.0, supports-color@1.3.1, buffer-equal@0.0.1, deep-equal@1.0.0, signal-exit@2.1.2, mkdirp@0.5.1, readable-stream@1.1.13, tap-mocha-reporter@0.0.14, tap-parser@1.1.6, glob@5.0.10, coveralls@2.11.2, nyc@2.3.0, js-yaml@3.3.1)
Finished npm install
--> Running step: echo nodejs information
node version v0.10.38 running
npm version 1.4.28 running
--> Steps passed
--> Pipeline finished


Building locally is very useful when you’re not sure your code will run because of some changes you made. As such you don’t want to push these changes to your Git provider just yet.

But since we’ve verified that our app is compiling and running correctly, it’s time to let wercker build & deploy your app in the cloud, which is what we’ll be doing in the next section.

Adding your app to wercker

The next step is to create a new application on wercker. Head over to and in the menu bar select create -> application.

Select your Git Provider

First select your Git provider, after which a list of your existing repositories on either GitHub or BitBucket is presented. Select the ruby example you forked earlier from the list and click on Use selected repo.


Select the owner

Now we have to choose who owns the app. For this tutorial, go ahead and select yourself. If you like, you can also select an organization you created on wercker. Click on Use selected owner once you’re ready.

Configure Access

The next step is about configuring access, and the first option - checkout the code without using an SSH key - is fine for the purpose of this tutorial, because it’s an open source and public application. So go ahead and click Next step


Configuring the wercker.yml

At this point wercker will try to detect if you have a wercker.yml file in your repository and if not, try to make one for you. However, we already have a wercker.yml file so let’s change that and click I already have a wercker.yml. Be sure to leave the Docker enabled as it is.

Finishing up

Finally, once you’ve verified all the settings you can click Finish to complete setting up our app! When done, you will be redirected to your very own app page, which looks empty now, so let’s go ahead and change that.

Triggering your first build

Wercker will automatically trigger a build every time you push new code to your Git provider. Let’s see that in action. In your working directory, run

$ git commit -am 'wercker build time!'
$ git push origin master

Next, navigate to your app page and you should see a new build has been triggered! This build will do the exact same as the one you triggered locally but now everyone in your team can see and comment on the build.


Wrapping up

Congratulations! You’ve built your first app using wercker. The next tutorial in this series will be about how to deploy your javascript app to a Digital Ocean server (Coming soon!).