Initial setup of a VS Code devcontainer for Rails; see https://everydayrails.com/2021/02/21/docker-devcontainer-series-setup.html

devcontainer.json

// For format details, see https://aka.ms/devcontainer.json. For config options, see the README at:
// https://github.com/microsoft/vscode-dev-containers/tree/v0.155.1/containers/ruby-rails
{
	"name": "Yet Another To-do App",
	"build": {
		"dockerfile": "Dockerfile",
		"args": { 
			// Update 'VARIANT' to pick a Ruby version: 2, 2.7, 2.6, 2.5
			"VARIANT": "2.5",
			"NODE_VERSION": "lts/*"
		}
	},

	// Set *default* container specific settings.json values on container create.
	"settings": { 
		"terminal.integrated.shell.linux": "/bin/bash"
	},

	// Add the IDs of extensions you want installed when the container is created.
	"extensions": [
		"rebornix.Ruby"
	],
	
	// Use 'forwardPorts' to make a list of ports inside the container available locally.
	"forwardPorts": [3000],

	// Use 'postCreateCommand' to run commands after the container is created.
	"postCreateCommand": "bin/setup",

	// Comment out connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
	"remoteUser": "vscode"
}

Dockerfile

# [Choice] Ruby version: 2, 2.7, 2.6, 2.5
ARG VARIANT=2
FROM mcr.microsoft.com/vscode/devcontainers/ruby:0-${VARIANT}

ARG NODE_VERSION="lts/*"
RUN su vscode -c "source /usr/local/share/nvm/nvm.sh && nvm install ${NODE_VERSION} 2>&1"

# [Optional] Uncomment this section to install additional OS packages.
# RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
#     && apt-get -y install --no-install-recommends <your-package-list-here>

# [Optional] Uncomment this line to install additional gems.
# RUN gem install <your-gem-names-here>

# [Optional] Uncomment this line to install global node packages.
# RUN su vscode -c "source /usr/local/share/nvm/nvm.sh && npm install -g <your-package-here>" 2>&1

setup

#!/usr/bin/env ruby
require 'fileutils'
include FileUtils

# path to your application root.
APP_ROOT = File.expand_path('..', __dir__)

def system!(*args)
  system(*args) || abort("\n== Command #{args} failed ==")
end

chdir APP_ROOT do
  # This script is a starting point to setup your application.
  # Add necessary setup steps to this file.

  puts '== Installing dependencies =='
  system! 'gem install bundler --conservative'
  system('bundle check') || system!('bundle install')

  # Install JavaScript dependencies if using Yarn
  # system('bin/yarn')

  puts "\n== Copying sample files =="
  unless File.exist?('.env')
    cp '.env.sample', '.env'
  end
  # unless File.exist?('config/database.yml')
  #   cp 'config/database.yml.sample', 'config/database.yml'
  # end

  # puts "\n== Preparing database =="
  # system! 'bin/rails db:setup'

  # puts "\n== Removing old logs and tempfiles =="
  # system! 'bin/rails log:clear tmp:clear'

  # puts "\n== Restarting application server =="
  # system! 'bin/rails restart'
end