Docker deployment in Ruby on Rails - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Docker in the context of Rails deployment?

Docker is a tool that packages your Rails app and its environment into a container. This container runs the app the same way everywhere, making deployment easier and consistent.

beginner

What is a Dockerfile and why is it important for Rails apps?

A Dockerfile is a simple text file with instructions to build a Docker image. For Rails, it defines the Ruby version, copies app files, installs gems, and sets up the app environment.

intermediate

How does Docker Compose help in deploying a Rails app?

Docker Compose lets you define and run multi-container apps. For Rails, it can start the app container, a database container, and others together with one command.

intermediate

Why should you use volumes in Docker when developing a Rails app?

Volumes let you share code between your computer and the Docker container. This means you can edit code on your computer and see changes immediately inside the container.

beginner

What is the role of environment variables in Docker deployment for Rails?

Environment variables store settings like database passwords or secret keys outside the code. Docker uses them to keep sensitive info safe and configure the app for different environments.

What does a Dockerfile typically specify for a Rails app?

A Ruby version, app files, gems, and commands to run the app

B Only the database configuration

C The HTML templates for the app

D User interface styles

A Dockerfile sets up the environment including Ruby version, copies app files, installs gems, and defines how to run the app.

Which command starts all services defined in a Docker Compose file?

A docker-compose up

B docker build

C docker run

D docker start

The 'docker-compose up' command starts all containers defined in the docker-compose.yml file together.

Why use Docker volumes during Rails development?

A To speed up the internet connection

B To share code changes instantly between host and container

C To increase CPU power

D To change the app's color scheme

Volumes sync code between your computer and the container, so changes appear immediately without rebuilding the image.

What is the main benefit of using Docker for Rails deployment?

A Faster coding speed

B Automatic bug fixing

C Consistent environment across all machines

D Free hosting

Docker ensures the app runs the same way everywhere by packaging the environment with the app.

How do environment variables help in Docker deployment?

A They create user accounts automatically

B They change the app's font size

C They speed up the app's loading time

D They keep sensitive info like passwords outside the code

Environment variables store sensitive data securely and allow easy configuration without changing code.

Explain how Docker and Docker Compose work together to deploy a Rails application.

Think about building and running containers for app and database.

Describe the purpose of using environment variables in Docker deployment for Rails apps.

Why not put secrets directly in your code?