Add Node.js web app example using CentOS

docs/sources/examples/index.rst

@@ -1,6 +1,6 @@
 :title: Docker Examples
 :description: Examples on how to use Docker
-:keywords: docker, hello world, python, couch, couchdb, redis, ssh, sshd, examples
+:keywords: docker, hello world, node, nodejs, python, couch, couchdb, redis, ssh, sshd, examples
 
 
 
@@ -16,6 +16,7 @@ Contents:
    hello_world
    hello_world_daemon
    python_web_app
+   nodejs_web_app
    running_redis_service
    running_ssh_service
    couchdb_data_volumes

docs/sources/examples/nodejs_web_app.rst

@@ -0,0 +1,225 @@
+:title: Running a Node.js app on CentOS
+:description: Installing and running a Node.js app on CentOS
+:keywords: docker, example, package installation, node, centos
+
+.. _nodejs_web_app:
+
+Node.js Web App
+===============
+
+.. include:: example_header.inc
+
+The goal of this example is to show you how you can build your own docker images
+from a parent image using a ``Dockerfile`` . We will do that by making a simple
+Node.js hello world web application running on CentOS.
+
+Create Node.js app
+++++++++++++++++++
+
+First, create a ``package.json`` file that describes your app and its
+dependencies:
+
+.. code-block:: json
+
+    {
+      "name": "docker-centos-hello",
+      "private": true,
+      "version": "0.0.1",
+      "description": "Node.js Hello World app on CentOS using docker",
+      "author": "Daniel Gasienica <daniel@gasienica.ch>",
+      "dependencies": {
+        "express": "3.2.4"
+      }
+    }
+
+Then, create an ``index.js`` file that defines a web app using the
+`Express.js <http://expressjs.com/>`_ framework:
+
+.. code-block:: javascript
+
+    var express = require('express');
+
+    // Constants
+    var PORT = 8080;
+
+    // App
+    var app = express();
+    app.get('/', function (req, res) {
+      res.send('Hello World\n');
+    });
+
+    app.listen(PORT)
+    console.log('Running on http://localhost:' + PORT);
+
+
+In the next steps, we’ll look at how you can run this app inside a CentOS
+container using docker. First, you’ll need to build a docker image of your app.
+
+Creating a ``Dockerfile``
++++++++++++++++++++++++++
+
+Create an empty file called ``Dockerfile``:
+
+.. code-block:: bash
+
+    touch Dockerfile
+
+Open the ``Dockerfile`` in your favorite text editor and add the following line
+that defines the version of docker the image requires to build
+(this example uses docker 0.3.4):
+
+.. code-block:: bash
+
+    # DOCKER-VERSION 0.3.4
+
+Next, define the parent image you want to use to build your own image on top of.
+Here, we’ll use `CentOS <https://index.docker.io/_/centos/>`_ (tag: ``6.4``)
+available on the `docker index`_:
+
+.. code-block:: bash
+
+    FROM    centos:6.4
+
+Since we’re building a Node.js app, you’ll have to install Node.js as well as
+npm on your CentOS image. Node.js is required to run your app and npm to install
+your app’s dependencies defined in ``package.json``.
+To install the right package for CentOS, we’ll use the instructions from the
+`Node.js wiki`_:
+
+.. code-block:: bash
+
+    # Enable EPEL for Node.js
+    RUN     rpm -Uvh http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
+    # Install Node.js and npm
+    RUN     yum install -y npm-1.2.17-5.el6
+
+To bundle your app’s source code inside the docker image, use the ``ADD``
+command:
+
+.. code-block:: bash
+
+    # Bundle app source
+    ADD . /src
+
+Your app binds to port ``8080`` so you’ll use the ``EXPOSE`` command to have it
+mapped by the docker daemon:
+
+.. code-block:: bash
+
+    EXPOSE  8080
+
+Last but not least, define the command to run your app using ``CMD`` which
+defines your runtime, i.e. ``node``, and the path to our app, i.e.
+``src/index.js`` (see the step where we added the source to the container):
+
+.. code-block:: bash
+
+    CMD ["node", "/src/index.js"]
+
+Your ``Dockerfile`` should now look like this:
+
+.. code-block:: bash
+
+
+    # DOCKER-VERSION 0.3.4
+    FROM    centos:6.4
+
+    # Enable EPEL for Node.js
+    RUN     rpm -Uvh http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
+    # Install Node.js and npm
+    RUN     yum install -y npm-1.2.17-5.el6
+
+    # Bundle app source
+    ADD . /src
+    EXPOSE  8080
+    CMD ["node", "/src/index.js"]
+
+
+Building your image
++++++++++++++++++++
+
+Go to the directory that has your ``Dockerfile`` and run the following command
+to build a docker image. The ``-t`` flag let’s you tag your image so it’s easier
+to find later using the ``docker images`` command:
+
+.. code-block:: bash
+
+    docker build -t <your username>/centos-node-hello .
+
+Your image will now be listed by docker:
+
+.. code-block:: bash
+
+    docker images
+
+    > # Example
+    > REPOSITORY                 TAG       ID              CREATED
+    > centos                     6.4       539c0211cd76    8 weeks ago
+    > gasi/centos-node-hello     latest    d64d3505b0d2    2 hours ago
+
+
+Run the image
++++++++++++++
+
+Running your image with ``-d`` runs the container in detached mode, leaving the
+container running in the background. Run the image you previously built:
+
+.. code-block:: bash
+
+    docker run -d <your username>/centos-node-hello
+
+Print the output of your app:
+
+.. code-block:: bash
+
+    # Get container ID
+    docker ps
+
+    # Print app output
+    docker logs <container id>
+
+    > # Example
+    > Running on http://localhost:8080
+
+
+Test
+++++
+
+To test your app, get the the port of your app that docker mapped:
+
+.. code-block:: bash
+
+    docker ps
+
+    > # Example
+    > ID            IMAGE                          COMMAND              ...   PORTS
+    > ecce33b30ebf  gasi/centos-node-hello:latest  node /src/index.js         49160->8080
+
+In the example above, docker mapped the ``8080`` port of the container to
+``49160``.
+
+Now you can call your app using ``curl`` (install if needed via:
+``sudo apt-get install curl``):
+
+.. code-block:: bash
+
+    curl -i localhost:49160
+
+    > HTTP/1.1 200 OK
+    > X-Powered-By: Express
+    > Content-Type: text/html; charset=utf-8
+    > Content-Length: 12
+    > Date: Sun, 02 Jun 2013 03:53:22 GMT
+    > Connection: keep-alive
+    >
+    > Hello World
+
+We hope this tutorial helped you get up and running with Node.js and CentOS on
+docker. You can get the full source code at
+https://github.com/gasi/docker-node-hello.
+
+Continue to :ref:`running_redis_service`.
+
+
+.. _Node.js wiki: https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager#rhelcentosscientific-linux-6
+.. _docker index: https://index.docker.io/