basic devcontainer

create-db-user.sql

CREATE USER vscode CREATEDB;
CREATE DATABASE vscode WITH OWNER vscode;

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/v0.222.0/containers/ruby-rails-postgres
// Update the VARIANT arg in docker-compose.yml to pick a Ruby version
{
	"name": "myapp",
	"dockerComposeFile": "docker-compose.yml",
	"service": "app",
	"workspaceFolder": "/workspace",

	// Set *default* container specific settings.json values on container create.
	"settings": { },

	// 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.
	// This can be used to network with other containers or the host.
	// "forwardPorts": [3000, 5432, 6379],

	// Use 'postCreateCommand' to run commands after the container is created.
	"postCreateCommand": "bundle install && yarn && rake db:setup",

	"postStartCommand": "sudo /etc/init.d/redis-server start",
	// Comment out to connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
	"remoteUser": "vscode"
}

docker-compose.yml

version: '3'

services:
  app:
    build:
      context: ..
      dockerfile: .devcontainer/Dockerfile
      args:
        # Update 'VARIANT' to pick a version of Ruby: 3, 3.1, 3.0, 2, 2.7, 2.6
        # Append -bullseye or -buster to pin to an OS version.
        # Use -bullseye variants on local arm64/Apple Silicon.
        VARIANT: "3.1-bullseye"
        # Optional Node.js version to install
        NODE_VERSION: "lts/*"

    init: true
    volumes:
      - ..:/workspace:cached

    # Overrides default command so things don't shut down after the process ends.
    command: sleep infinity

    environment:
      DATABASE_USERNAME: vscode
      DATABASE_PASSWORD: ''

    # Runs app on the same network as the database container, allows "forwardPorts" in devcontainer.json function.
    network_mode: service:db
    # Uncomment the next line to use a non-root user for all processes.
    # user: vscode

    # Use "forwardPorts" in **devcontainer.json** to forward an app port locally.
    # (Adding the "ports" property to this file will not forward from a Codespace.)

  db:
    image: postgres:latest
    restart: unless-stopped
    volumes:
      - postgres-data:/var/lib/postgresql/data
      - ./create-db-user.sql:/docker-entrypoint-initdb.d/create-db-user.sql
    environment:
      POSTGRES_USER: postgres
      POSTGRES_DB: postgres
      POSTGRES_PASSWORD: postgres
    # Add "forwardPorts": ["5432"] to **devcontainer.json** to forward PostgreSQL locally.
    # (Adding the "ports" property to this file will not forward from a Codespace.)

volumes:
  postgres-data: null

Dockerfile

# [Choice] Ruby version (use -bullseye variants on local arm64/Apple Silicon): 3, 3.1, 3.0, 2, 2.7, 2.6, 3-bullseye, 3.1-bullseye, 3.0-bullseye, 2-bullseye, 2.7-bullseye, 2.6-bullseye, 3-buster, 3.1-buster, 3.0-buster, 2-buster, 2.7-buster, 2.6-buster
ARG VARIANT=2-bullseye
FROM mcr.microsoft.com/vscode/devcontainers/ruby:0-${VARIANT}

# Install Rails
RUN gem install rails webdrivers 

# Default value to allow debug server to serve content over GitHub Codespace's port forwarding service
# The value is a comma-separated list of allowed domains 
ENV RAILS_DEVELOPMENT_HOSTS=".githubpreview.dev"

# [Choice] Node.js version: lts/*, 16, 14, 12, 10
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 postgresql-client curl

# [Optional] Uncomment this line to install additional gems.
RUN gem install foreman bundler:2.2.33

# [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