The provided code is a Dockerfile, which is a script used to create a Docker image. A Docker image is a lightweight, standalone, executable package that includes everything needed to run an application, including the code, runtime, system tools, system libraries, and settings.
Here's a breakdown of what the code does:
Base Image : The Dockerfile starts by specifying the base image as the latest version of Ubuntu (FROM ubuntu:latest).
Metadata Labels : Several labels are added to provide metadata about the image, such as the maintainer, source code repository, description, and licenses.
Environment Variable : The ARG instruction sets an environment variable DEBIAN_FRONTEND to noninteractive, which is used to run apt-get in a non-interactive mode.
Package Installation : The RUN instruction updates the package lists, upgrades the installed packages, and installs various packages such as locales, sudo, build essentials, programming languages (zsh, curl, wget, git, gnupg, keychain, rustc, and more), and development libraries.
User Creation : A new user named "devops" is created with a password "devops" and added to the sudo group.
GitHub CLI and Node.js Installation : A separate RUN instruction installs the GitHub CLI and the latest LTS version of Node.js from their respective PPAs (Personal Package Archives).
Python Version : The update-alternatives command is used to set the system's default Python version to Python 3.
Exposed Ports : The Dockerfile exposes ports 3000 and 5432, which are commonly used for web applications and databases, respectively.
Working Directory and User Context : The working directory is set to /home/devops, and the user context is changed to the non-privileged "devops" user.
Oh My Zsh Installation : The Oh My Zsh framework is installed for the "devops" user to enhance the Zsh shell experience.
PyEnv Installation : PyEnv, a Python version management tool, is installed for Python developers.
rbenv and ruby-build Installation : rbenv and ruby-build are installed for Ruby developers, and a directory for Git repositories is created.
Node Version Manager (NVM) Installation : NVM is installed to allow JavaScript developers to select and use different versions of Node.js.
Environment Variables : Several environment variables are set, such as the shell (SHELL), language (LANG), terminal emulator (TERM), and default text editor (EDITOR).
Default Command : The default command to be executed when the container starts is set to /usr/bin/zsh, which will launch the Zsh shell.
Overall, this Dockerfile sets up a development environment within a Docker container, including various programming languages, tools, and utilities commonly used by developers. It creates a non-privileged user account named "devops" and installs version managers for Python, Ruby, and Node.js, allowing developers to work with different versions of these languages within the container.
- Install Docker Desktop on your machine.
- Install Git For Windows
- From either Powershell or a regular CMD window, execute the following:
git clone https://github.com/dderyldowney/devops-docker.git
cd devops-docker
docker build --rm --no-cache -t devops-docker:latest -f Dockerfile .This will build the image and tag it as devops-docker:latest
To use the image for actual development, you can run:
docker run --rm -ti --name devops devops-docker:latestRemember that as soon as you exit the resulting container your stuff disappears, and the container returns to the image state. If you want to persist your work, like cloned git repos, you will need to create and use a Docker volume. For example, you can create a volume and mount it when you create a container as follows:
docker volume create github
docker run --name devops -dt -v github:/home/devops/github devops-docker:latest
docker attach devopsThis will
- Create a docker volume
- Attach it to
/home/devops/githubin the resulting container - Put the container into the background with a pseudo tty
- The last command will connect you to it
When you log in, you should see the github directory in the devops user's $HOME.
This is where that volume you created earlier is mounted for long term storage.
Everything that goes into this directory will persist for later use.
Change into that directory and clone whatever repositories you want/need. When you disconnect, stop, or even delete the container your data will be safe and sound in that volume. Cool thing is you can attach it to whatever other containers you wish, as well.
Lets say you want to add more packages but don't want to constantly have to rebuild the image. You can update the image you've already built by doing commits from the container against the image.
For example, lets say you decide to install Apache webserver but don't want to specify that in the initial image build (ie. in the Dockerfile itself). Or, say you install rbenv or add a .gitconfig. No problem at all! WITHOUT exiting the running container, open another shell/cmd/terminal on the host machine and simply do the following steps in that shell/cmd/terminal:
Run docker container ls and find the CONTAINER ID sha.
$ docker container ls
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
210f5cd9e972 b57a6804f9e1 "/bin/bash" 4 hours ago Up 5 seconds devops
$Copy that sha and run the following command:
docker commit 210f5cd9e972 devops-docker:latestYou can now close the terminal, then exit and stop the container you're working in.
That's it! Now, whenever you create a new container from your existing devops-docker:latest image
it will contain anything you've added up to, and including, that particular sha.
Made more changes? No problem! Simply wash, rinse, and repeat.
NOTE: If you have a Docker Hub account you can create a repo there, and simply push your image up. Remember to re-push every time you make a new commit against the original image from the container to keep the Docker Hub image constantly up to date without having to do a complete rebuild.
docker push <your_hub_username>/devops-docker:latestThat's about it for now! If you have any suggestions or improvements, feel free to open an Issue or make a Pull Request.
Enjoy!
POSTNOTE: I'll be adding how to work with docker-compose using this repository, so watch for a docker-compose.yml
and these instructions to be updated! Full service fun! Woot!
"Keep moving foward! Learn something new every day!" -- D Deryl Downey