0. Inform
This is basically a copy of the Hello World example found
here
and
here with some additional comments.
1. Make the VM running
boot2docker up
2. Build the Docker image
Create your Node.js application
index.js file:
var express = require('express');
var DEFAULT_PORT = 8080;
var PORT = process.env.PORT || DEFAULT_PORT;
var app = express();
app.get('/', function (req, res) {
res.send('Hello World\n');
});
app.listen(PORT)
console.log('Running on http://localhost:' + PORT);
Create the Docker
package.json file:
{
"name": "docker-centos-hello-world",
"private": true,
"version": "0.0.1",
"description": "Node.js Hello World app on CentOS using docker",
"author": "Daniel Gasienica",
"dependencies": {
"express": "3.2.4"
}
}
Create the
Dockerfile:
FROM centos:6.4
RUN rpm -Uvh http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
RUN yum install -y npm
ADD . /src
RUN cd /src; npm install
EXPOSE 8080
CMD ["node", "/src/index.js"]
The layout of your directory should be as follows:
> ls
Dockerfile index.js package.json
Building the image:
docker build -t peter/centos-node-hello .
Verify if the image exists:
docker images
This should print:
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
peter/centos-node-hello latest 6c55823e6868 4 hours ago 672.2 MB
3. Running
docker run -p 49160:8080 -d peter/centos-node-hello
The option
-p exposes the port
8080 to
49160. This is essential. Without that, the server is not visible to a client.
Verify, if the process is running:
docker ps
You should see:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
578bd01b0407 peter/centos-node-hello:latest node /src/index.js 4 hours ago Up 2 hours 0.0.0.0:49160->8080/tcp jovial_feynman
Inspect the image:
docker inspect 578bd01b0407
You should see a JSON output showing all relevant information:
...
"PortBindings": {
"8080/tcp": [
{
"HostIp": "0.0.0.0",
"HostPort": "49160"
}
]
}
...
If the
-p was not given when starting the process,
HostPort would have been
null and the application would not have been visible to clients.
Test it:
curl localhost:49160
Now you should see:
Hello World.
Stop and start the process again:
docker stop 578bd01b0407
docker ps doesn't show the process any more.
docker ps -a lists the process as
Exited:
> docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
578bd01b0407 peter/centos-node-hello:latest node /src/index.js 12 minutes ago Exited (143) 9 seconds ago jovial_feynman
So, start it again:
docker start 578bd01b0407
Test if the process is running:
> docker -ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
578bd01b0407 peter/centos-node-hello:latest node /src/index.js 14 minutes ago Up 2 seconds 0.0.0.0:49160->8080/tcp jovial_feynman
Check the logs:
> docker logs 578bd01b0407
Running on http://localhost:8080
Running on http://localhost:8080
