Dockerizing Rails - A supercharged development process

Preparing for the workshop

Please make sure to install

• Docker Engine - Community => https://docs.docker.com/install/
• Git => https://git-scm.com/downloads

Make sure to create a Docker ID if you don't have one already: https://hub.docker.com/signup

Clone this repository so that we can iterate on it later in the workshop:

git clone https://github.com/jcoyne/dockerizing_rails

Testing your Docker installation

Run the following command on you system:

docker version

The output of the command should look similar to this:

Client: Docker Engine - Community
 Version:           19.03.2
 API version:       1.40
 Go version:        go1.12.8
 Git commit:        6a30dfc
 Built:             Thu Aug 29 05:26:49 2019
 OS/Arch:           darwin/amd64
 Experimental:      false

Server: Docker Engine - Community
 Engine:
  Version:          19.03.2
  API version:      1.40 (minimum version 1.12)
  Go version:       go1.12.8
  Git commit:       6a30dfc
  Built:            Thu Aug 29 05:32:21 2019
  OS/Arch:          linux/amd64
  Experimental:     true
 containerd:
  Version:          v1.2.6
  GitCommit:        894b81a4b802e4eb2a91d1ce216b8817763c29fb
 runc:
  Version:          1.0.0-rc8
  GitCommit:        425e105d5a03fabd737a126ad93d62a9eeede87f
 docker-init:
  Version:          0.18.0
  GitCommit:        fec3683

The important parts here are

• Version for the Client and Server should be 18.09.0 or higher Please update your Docker installation if you are on an older version.
• Under Server: Docker Engine - Community make sure that the OS/Arch says linux/amd64. If you are seeing Windows in there, please make sure to switch you Docker installation to run Linux: https://docs.docker.com/docker-for-windows/#switch-between-windows-and-linux-containers

Verifying Docker Compose version

Run the following command on you system:

docker-compose -v

The output of the command should look similar to this:

docker-compose version 1.24.1, build 4667896b

If you are running an older Version of Docker Compose or you are getting a command not found, please follow the installation instructions for Docker Compose: https://docs.docker.com/compose/install/

Pre-loading images

To save time and bandwidth throughout the workshop, I recommend that you download the container "images" that we will use beforehand. Don't worry if you don't know what an image is yet - we will go over that in the workshop. All you have to do is execute the following commands:

docker image pull ubuntu:18.04
docker image pull jfahrer/ruby:2.6.3-alpine3.10-ser
docker image pull redis:5.0
docker image pull postgres:10.6-alpine

The output will look similar to this:

2.6.3-alpine3.10-ser: Pulling from jfahrer/ruby
bdf0201b3a05: Pull complete
67a4a175230f: Pull complete
5b688ca58800: Pull complete
68bfb7317906: Pull complete
e95e2e8e402a: Pull complete
5e7827d9c7e8: Pull complete
4507d0429dd7: Pull complete
7cba2dc1349a: Pull complete
61e576b94017: Pull complete
951629f33eb5: Pull complete
Digest: sha256:b1a4210e93b94e5a09a6e9c8f44c8f0a2aef03c520d6268faa20261c55d6d2b7
Status: Downloaded newer image for jfahrer/ruby:2.6.3-alpine3.10-ser

Assignments

Throughout the workshop you will complete the following assignments:

• Assignment 1 - Hello World
• Assignment 2 - Your first image
• Assignment 3 - Running Rails
• Assignment 4 - Talking to a service
• Assignment 5 - Integrating Postgres
• Assignment 6 - Utilizing layers
• Assignment 7 - Glueing things together
• Assignment 8 - Iterating
• Assignment 9 - Debugging
• Assignment 10 - Integrating Sidekiq
• Assignment 11 - Installing Webpacker
• Assignment 12 - Keeping things running with Spring
• Assignment 13 - Scripts To Rule Them All
• Assignment 14 - A seamless experience

TLDR - I just want to see a dockerized Rails app

Check out the dockerized branch and run script/setup to start the application.

Learning more

Additional topics

There are more topics that didn't quite fit into the workshop.

• Running the application as a different user
• Advanced caching mechanisms for gems and libraries
• Making use of environment variables to change the development environment
• Integration testing with Capybara/Cypress
• Utilizing CI/CD
• Preparing your image for production
• Deploying to Kubernetes And much more.

Sign up at RailsWithDocker.com and Julian will shoot you an email as soon as the material is ready.

Resources

• https://LearnDocker.online: Free resource with 11+ hours of video content teaching you everything I know about Docker and Containers.
• https://RailsWithDocker.com: Free online resource teaching you how to dockerize a Rails app. It covers everything you learned in this workshop and more.
• https://docs.docker.com: The official Docker documentation

Doing more

Nothing better than practicing your newly acquired skills. I suggest that you dockerize one of you applications or extend the demo app with some additional functionality. Here are some ideas:

• Paginate activities and todos
• Add a filter to display archived todos: There is currently no way to show archived todos
• Add a search engine: Use Elasticsearch, Solr, or another searchengine to make todos searchable
• Soft delete todos: We currently allow users to delete todos from the database
• Add a Sidekiq monitor (https://github.com/mperham/sidekiq/wiki/Monitoring): Try to run the monitor in as its own Rack app in its own container

Contributions

Course developed by Julian Fahrer @jfahrer and presented at RailsConf 2019. Special thanks to @hjhart and @palexvs for all their help with this workshop.