GitHub

Principles

  • One Dockerfile with multi-stage builds to support both development and production builds.
  • One docker-compose.yml to target only the "development" stage of the Dockerfile, optimized for development speed, aka engineer happiness.
    • Make Docker fast enough for development with persisted volumes for all dependencies and generated content (bundle node_modules, packs, etc)
    • Get as close as possible to local / non-Docker development speed with separate webpack-dev-server and HMR - hot module reloading
    • All credit goes to Ruby on Whales for this and much of the Dockerfile development target
  • Automate setting up Docker/local development with VS Code tasks.
    • Run "build" tasks in VS Code that open/reload multiple shells for either:
      • Docker development
      • Local development
  • IN PROGRESS - Github Actions CI/CD pipeline to Kubernetes

Setup

Install

  • Install Docker Desktop
  • (recommended) Install OhMyZsh for Zsh shell shortcuts in comments below for each shell command
  • (recommended) Install VS Code to use multi-shell tasks like "Docker development", see .vscode/tasks.json

Run

  • If you clone this repo, you'll need to recreate the config/credentials.yml.enc
  • And for Github Actions to work, you'll need to set RAILS_MASTER_KEY in the Repo Settings :: Secrets.
# Step 1
# Delete example credentials.yml.enc
rm config/credentials.yml.enc
EDITOR=vim rails credentials:edit
# Then type: `:wq` to exit and save
# Step 2
# NEXT: Copy and paste the value now in config/master.key
# into the Github repository secrets as `RAILS_MASTER_KEY`
# Step 3
# Push up a commit and then trigger a build
.dockerdev/build.sh
  • More initial setup for local development
# Build the development (target) image
# dcb     <- Oh My Zsh shortcut (if installed)
docker-compose build
# Set up database by running rake db:setup  (rake db:create; rake db:schema_load)
# dcr --rm bash rake db:setup   <- Oh My Zsh shortcut (if installed)
docker-compose run --rm bash rake db:setup

Development

  • Use VS Code and CTRL/CMD-SHIFT-B to show "build" tasks from .vscode/tasks.json
    • Docker development
    • Local development
  • Or manually run whatever you like, typically for development
    • docker-compose up webpacker - install gems, packages, and run webpack-dev-server
    • docker-compose up rails - run rails server
    • docker-compose run --rm bash - a "runner" to keep up for quick debugging
  • Note: Oh My Zsh aliases are comments below (dcb for docker-compose build)...
# Script to start Docker on Mac
.dockerdev/docker-start.sh
# dcb
docker-compose build
# dcup webpacker
docker-compose up webpacker
# dcup rails
docker-compose up rails
# Keep this bash "runner" up for db:migrate, rails c, etc
# dcr --rm bash
docker-compose run --rm bash
# Rake tasks
# dcr --rm bash rake db:migrate
docker-compose run --rm bash rake db:migrate
# dcr --rm bash rake db:setup
docker-compose run --rm bash rake db:setup
# dcr --rm bash rake db:reset
docker-compose run --rm bash rake db:reset

Production builds

  • Calling docker build on the Dockerfile without target=development will build an image for production
    • The production image only includes the app's code, Ruby, gems, and precompiled packs and assets.
      • No NodeJS, node_modules in the final production image
BUILD_DATE=$(date +%Y%m%d-%H%M%S)
docker build -t demo_app:$BUILD_DATE .
# Use docker run  with `bash` to check on that build image
docker run --name demo_app_latest --rm -i -t demo_app:$BUILD_DATE bash

Debugging

# dcr --rm bash
docker-compose run --rm bash

Oh My Zsh aliases for Docker

dcb='docker-compose build'
dcdn='docker-compose down'
dce='docker-compose exec'
dck='docker-compose kill'
dcl='docker-compose logs'
dclf='docker-compose logs -f'
dco=docker-compose
dcps='docker-compose ps'
dcpull='docker-compose pull'
dcr='docker-compose run'
dcrestart='docker-compose restart'
dcrm='docker-compose rm'
dcstart='docker-compose start'
dcstop='docker-compose stop'
dcup='docker-compose up'
dcupb='docker-compose up --build'
dcupd='docker-compose up -d'

Clean up

# Remove dangling containers, images, volumes, etc
docker system prune
# Remove ALL stopped, not just dangling
docker system prune -a
# Remove ALL stopped, including volumes (local data loss!)
 docker system prune -a --volumes

Credits and Resources

More Reading

Linting

Use hadolint to lint: hadolint Dockerfile

Misc

Git hooks

  • Copy and paste code below to protect main branch from git push by admins
cat << 'DOC' > .git/hooks/pre-push
#!/bin/bash

protected_branch='main'
current_branch=$(git symbolic-ref HEAD | sed -e 's,.*/\(.*\),\1,')

if [ $protected_branch = $current_branch ]
then
    read -p "You're about to push to main, is that what you intended? [y|n] " -n 1 -r < /dev/tty
    echo
    if echo $REPLY | grep -E '^[Yy]$' > /dev/null
    then
        exit 0 # push will execute
    fi
    exit 1 # push will not execute
else
    exit 0 # push will execute
fi
DOC
chmod +x .git/hooks/pre-push

Read the original on github.com ↗