Rails Applications with Docker
•
13 likes•8,079 views
A brief introduction to containerization, Docker, and getting started with your first containerized Rails application. Source code can be found at https://github.com/rheinwein/rails-demo-apps
Report
Share
Rails Applications with Docker
- 1. Building Rails Applications with Docker Laura Frank @rhein_wein Software Engineer @codeship
- 2. Today’s Agenda • An introduction to containers: what are they, and what makes them different from virtual machines? • The Docker ecosystem • Working with Docker on a Rails project 2
- 3. An Introduction to Containerization
- 6. Docker manages containers • Builds images to run as containers • Can manage entire applications with docker-compose • Provision machines with docker-machine 6
- 7. A container is a virtualization layer — sort of like a VM — but with some fundamental differences
- 8. Containers • Run in a self-contained execution environment • Share the kernel of host system • Are isolated from other containers • Have fast boot times & low overhead 8
- 9. infrastructure host OS hypervisor $ guest OS libraries service 0 $ guest OS $ guest OS libraries service 2 libraries service 1
- 10. libraries librarieslibraries infrastructure host OS service 0 service 2service 1
- 11. host OS libraries librarieslibraries infrastructure container runtime engine service 0 service 2service 1
- 12. Getting started with containers may initially seem more complex…
- 13. …But they greatly reduce the amount of time and space needed to run your application
- 14. Spend less time provisioning, rebooting, and fighting with dependencies, and more time building what you want. TL;DR
- 16. Build Ship Run
- 17. Docker Images
- 18. Are images containers? No… an image is like a class, and a container is an instance of that class
- 20. • ~15,000 images that you can pull down and use in your own projects • Also includes additional features like webhooks, build triggers, authentication, and private repositories • Use either the web GUI or the CLI — familiar workflow of login, push, pull, search, etc. The Docker Hub
- 21. Different Types of Images • Service: self-contained images that provide a self- contained service out-of-the-box. Postgres, MySQL. • Project Base: intended to serve as a base for your own project; do not directly provide a service. Ruby, golang. • Official Images: maintained by the organization/ company themselves (i.e. the official Rails image)
- 22. • Build them yourself by creating a Dockerfile • docker build -‐t image_name . # don’t forget the dot! • run docker images to see all of the images you’ve downloaded or built Your Own Docker Images
- 23. A Rails Dockerfile FROM rails:4.2.4 MAINTAINER Laura Frank <laura@codeship.com> RUN mkdir -p /var/app COPY . /var/app WORKDIR /var/app RUN bundle install CMD rails s -b 0.0.0.0 set versions here
- 24. Use the Docker Hub to find and store images to use in your project. Use Docker Compose to build it.
- 26. Building Your First Rails App with Docker
- 27. Installing Docker • The old way: boot2docker • The new way: Docker Toolbox • Docker Client, Machine, Engine, Compose (on a Mac), Kitematic, and Virtual Box • You can migrate your boot2docker VM to a Docker Machine machine — check the docs
- 29. Development Goals Run a Rails app in a container, so that a developer can: • view the app running in the browser • edit files in a local environment and see the changes • run rake tasks like migrations • see log output
- 30. Remember This? FROM rails:4.2.4 MAINTAINER Laura Frank <laura@codeship.com> RUN mkdir -p /var/app COPY Gemfile /var/app/Gemfile WORKDIR /var/app RUN bundle install CMD rails s -b 0.0.0.0
- 32. 🚉 🐘 A Multi-‐Container Rails App Rails App Postgres ❤
- 33. How can I get containerized services to communicate with one another?container linking, environment variables… and of course, a little config sugar
- 34. Docker Compose makes this easy.
- 35. db: image: postgres web: build: . command: bundle exec rails s -‐p 3000 -‐b '0.0.0.0' volumes: -‐ .:/var/app ports: -‐ '3333:3000' links: -‐ db docker-‐compose.yml
- 36. development: &default adapter: postgresql encoding: unicode database: postgres pool: 5 username: postgres password: host: db config/database.yml
- 38. Ship It A simple CI/CD workflow would include • running tests • building a new Docker image • pushing that image to a registry • firing up containers with the new image
- 40. thanks!