Liveblog: Hello Docker by Chuck Shotton

Liveblog:

Hello Docker by Chuck Shotton

Tue, May 12, 2015 at 12:38 PM by Dave Winer ☮.

Hello Docker by Chuck Shotton

This should demonstrate how to take a folder of source code, load it into a Docker container, and run the node.js app inside the Docker environment
- It should also show how to pass in external command line and environment variable arguments into the container when it launches
The big picture flow:
- Set up a new AWS Ubuntu instance (or us an existing one)
  - Expose ports 22, 3000, and 8080 for TCP/IP traffic
- Install git and docker packages
- Pull the sample project folder from GitHub
- Test the node.js app locally before running in Docker
- Build a local Docker image from the project folder and run it
1. Sign onto your Ubuntu instance and become superuser
- sudo su -
2. Update package sources and install git and docker
- apt-get update
- apt-get install git
- apt-get install docker.io
- If Node.js isn't already installed:
  - apt-get install npm
  - apt-get install node.js
3. Make sure they installed correctly
- git --version
- docker version
4. Log out as superuser
- control-D or exit
5. Get a copy of the GitHub repo
- git clone https://github.com/cshotton/hello_docker.git
- Note, you should now be in your home directory. Otherwise, cd to whatever folder you want your sample project to be installed into.
6. Install node dependencies and run the app locally for a test
- cd hello_docker
- npm install
7. Run the app with an environment variable set for testing
- export HELLO_DOCKER_ENV="env var goes here"
- npm start
  - If this command fails, it might be because node.js is installed as the binary "nodejs" instead of "node". If this is the case, edit the package.json file and change the "start" command to use nodejs instead of node.
8. Check the server:
- http://your.server.ip:3000/
- You should see the environment variable echoed in your web browser
- control-C to stop the server
9. Make a docker container and run it
- sudo docker build -t username/hello-docker .
  - substitute your username -- this command builds the image in the local docker server's image cache from the Dockerfile in the local directory (the "." arg). You will find the image later by the name you provide after the -t arg, using the docker images command
  - This command takes a while to run as it is building the full sandbox by pulling in lots of container parts
- sudo docker images
  - You should see your docker image listed
- sudo docker run -p 8080:3000 -e HELLO_DOCKER_ENV="some env vars" username/hello-docker
  - This command runs your docker image (username/hello-docker). It maps the external port 8080 to the internal container port 3000. It also passes in and sets the container's HELLO_DOCKER_ENV environment variable.
  - http://your.server.ip:8080/
  - If you want to run the container as a background server process, you can add the -d command to the command line before the image name.
    - If you do this, you can use the "sudo docker ps" command to see the running containers and use "sudo docker stop xxx" command, where "xxx" is the first 3 or 4 characters of the process ID shown in the "docker ps" command output.
What's next?
- First, you should only "dockerize" an app when you are ready to deploy it. Just build and test as usual with node.js until you are ready to roll it out into production, with multiple containers running on a machine (for example).
- You can build your own Docker images and upload them to repositories, like npm, etc. You can also run your own private repository for your images if you don't want them to be repurposed by the general public.
- As you might have guessed, you can run multiple copies of the same container on the same machine by just remapping port numbers to the new container (i.e. -p 8080:3000 and -p 3000:3000 on 2 separate docker run commands)
- Docker resources for Mac
  - https://docs.docker.com/installation/mac/
- Finally, you probably want to read the Docker docs...
- git clone https://github.com/cshotton/hello_docker.git