How to set up Docker to Dev Environment

09:30


On this Blog post, I will be using Dockerfile to setup development environment. Dockerfile is a script, composed of different commands and arguments listed successively to automatic performs actions on a base image in order to create a new one. They are use for organizing things and greatly help with deployments by simplifying the process start-to-finish.
As an example, the setup going to use iojs to be the web server running inside the Docker container.
However, I have came across on different kind of errors and found a solution that worked for me. I will update this post as I learn more and drawbacks with this approach.

Installing Docker

If you have not installed Docker head over on my previous blog post

Setting up the project

The set up going to use to initialize my development  environment:
  • Windows 8.1
  • Docker version 1.8.0, build 0d03096
  •  Boot2Docker-cli version: v1.8.0rtual
The idea is to have your project  source code on your host machine and mount it to the Docker container that execute a command to start your application and enables you to view it on your browser.

Dockerfile


# Base image stable Ubuntu 14.04
FROM ubuntu:14.04

# Replace shell with bash so we can source files
RUN rm /bin/sh && ln -s /bin/bash /bin/sh

# Add Author
MAINTAINER Ronald San Diego

# Install application dependencies
RUN apt-get update && apt-get install -yq build-essential \
        libssl-dev \
        curl \
        npm \
        ca-certificates \
        rsync \
        software-properties-common \
        wget \
        dos2unix \
        zlib1g-dev \
        gcc \
 make \
 g++ \
        && apt-get clean
# Clean out apt-get - So we don't store extra space on the image.

# Install NodeJs
RUN curl --silent --location https://deb.nodesource.com/setup_0.12 | sudo bash -
RUN sudo apt-get install --yes nodejs

# Install npm
RUN sudo npm install npm -g 

# Install node v4.0.0 
RUN npm cache clean -f
RUN npm install -g n
RUN n stable

# Fixing npm permission - to run globally
RUN mkdir ~/npm-global
RUN npm config set prefix '~/npm-global'

ENV PATH  ~/npm-global/bin:$PATH

RUN npm install -g nodemon --save

# Add this script in /usr/local/bin/ directory
ADD start-project.sh /usr/local/bin/

RUN chmod +x /usr/local/bin/start-project.sh \
 && dos2unix /usr/local/bin/start-project.sh

# Execute the application when container created
CMD bash -C '/usr/local/bin/start-project.sh';'bash'

# Expose port 8080 of container 
EXPOSE 8080

To note: 

  1. When using the ADD command in Dockerfile to add files, the files need to be on the same directory where the Dockerfile you are creating. Also, I added the "chmod +x" command to enable the script to be executable. 
  2. The CMD command is used to execute specific command whenever a container is created, on this case we will execute the script called start-project.sh.

Content of start-project.sh


#!/bin/bash 
 
cd /myProject 
nodemon hello.js

Example hello-world application

var http = require('http');
http.createServer(function (request, response) {
    response.writeHead(200, {'Content-Type': 'text/plain'});
    response.end('Hello World\n');
}).listen(8080);
console.log('Server started');
The code above is a simple iojs hello-world application.
  1. Create a new application name "hello.js" and put the code above on this file.
  2. Create a new folder name "myProject" (any name if you want) and put hello.js on this folder.
Your folder should have similar files as shown in the image below:

Build Docker image using Dockerfile

Once your Docker running smoothly and your source code application, you can start setting up the docker image.
  • Open up your "boot2docker" (CLI should pop up) 
  • Change directory of where your Dockerfile is located
  •  Run the command below:
docker build -t myproject/dev .

-t stand for tag name which the image name you want to be and . is to execute Dockerfile on the directory you are in and start creating the image.
PS: The Dockerfile execution might take a while

Creating container

One of the cool feature Docker is having a symlink meaning you can link a folder or file from your host machine to the Docker container. This a cool way to have because you don't need to be in the container and edit it.
We also installed nodemon so whenever something changed in a file that nodemon monitoring, it should restart the application automatically.
To do symlink in Docker, when we create a container a flag -v to allow you to mount the directory of your application from host machine into the container.

Problem Encountered

If you are using Window/Mac OS (Operating System) you might encountered this problem that Docker seems to be not working with symlink on nodemon meaning if nodemon already monitoring the files and you changed something it would not restart your application so you need to manually restart nodemon for the change to happen. The command below is an example of how you would mount folder to your container. 
docker run -dit -p 8080:8080 -v //full/path/to/project/folder/://nameoffoldertocontainer --name nameofcontainer namedockerimg
Example:
docker run -dit -p 10000:8080 -v //c/Users/Ronald/myProject/://myProject --name localhost localhost/dev

In a Windows/Mac OS you need to add "//" when specifying the full path of files/folders you want to mount in the container.

Proposed solution (for the moment)

  1. If you are planning to enhance your developing skills I would suggest to start using Linux OS. The previous steps should work with Ubuntu.
  2. Edit your Dockerfile and add your project folder. The folder need to be on the same directory of your Dockerfile. Rerun the command to build the image and create your docker container.
docker run -dit -p 8080:8080 --name localhost localhost/dev
Go to your browser and type your boot2docker IP and the open port on your host. If your unsure of the IP, type in your CLI:

boot2docker ip

To get in your container you can use the command: 
docker exec -it namecontainer bash

Conclusion

The setup mention is not ideal in a Windows/Mac if your planning to set a Development environment with Docker when your environment is based on iojs. It might be a good use if you will be using different kind of setup.
Based on experience if your production environment is based on Ubuntu, you should have Ubuntu for developing to make your life easier.
Idea of this post is not initially make the example work but to give you the idea on how you can use Docker in an Development Environment.

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