Containerd Rails

Overview

containerd_rails is a Rails application designed to run in a Docker container. This guide will walk you through the steps to set up and run the application both as a single container and as a multi-container application using Docker Compose.

Commands Run

Initial Setup

1. Create a new Rails application using SQLite3 as the database:

   rails new containerd_rails (app_name)

2. Build the Docker image:

   docker build -t app_image .

3. List Docker images to confirm the build:

   docker images

4. Run the container to access the bash shell (useful for generating a master key if using production environment):

   docker run -it --user root --rm --entrypoint bash app_image

   To generate a master key:

   rails credentials:edit

5. For development environment, change ENV to development. If using production, provide the RAILS_MASTER_KEY:

   docker run -p 3000:3000 -e RAILS_MASTER_KEY=1234567890 app_image

6. Update the Dockerfile to bind the Rails server to all IP addresses:

   CMD [".bin/rails", "server", "-b", "0.0.0.0"]

Developing in Docker using Bind Mounts

Run the container with bind mounts to reflect changes in real-time without rebuilding the image:

docker run -p 3000:3000 -v $(pwd):/rails app_image  (name of the image)

Multi-Container Application

Setting Up Multi-Container Application (Branch: multi-container)

1. Create a docker-compose.yml file.
2. Update the Gemfile and Dockerfile to use PostgreSQL instead of SQLite3.
3. Modify database.yml to set the host as the service name defined in docker-compose.yml.
4. Create a .env file for environment variables.

Commands

1. Start the application and access the web container's bash shell:

   docker-compose exec web bash

2. Create the database and generate a scaffold:

   bin/rails db:create
   bin/rails g scaffold Post title:string content:text
   bin/rails db:migrate

3. Restart the web service:

   docker-compose restart web

Logs

View logs for the database and web services: sh docker-compose logs db docker-compose logs web

Restarting

To restart the application:

1. Bring down the containers:

   docker-compose down

2. Bring the containers back up, rebuilding if necessary:

   docker-compose up -d --build

Clean everything

docker system prune -a