This builds a Docker image that is used by my book, Sustainable Web Development with Ruby on Rails.

If you just want to follow along, I suggest you pull the image from Docker Hub, set up the docker-compose.yml file as directed and go from there.

This repo is how that image is built, and you can use this to make your own.

• Ruby & Bundler
• Node
• Rails
• Chromedriver

The image is quite large because it installs all the gems needed for a new Rails app to work. In theory, when you use this image, rails new will not need to install any gems from the Internet.

1. Clone this repo
2. Make sure you have Docker installed
3. Edit bin/vars. In particular, you will need to modify:
   • ACCOUNT - account name on Docker Hub (used for naming the image only, but if you plan to push, make sure this value is accurate)
   • REPO - repo name for Docker Hub (again, only used for naming the image, but if you are going to push, make sure you have created this repo on Docker Hub. It does not need to be public)
   • TAG - tag for the image. Recommend you come up with a good scheme to avoid confusing locally. I use «rails-version»--«ruby-version», e.g. rails-7.0.4--ruby-3.1.3
4. Edit Dockerfile.template and docker-compose.yml.template as needed to change stuff. DO NOT edit Dockerfile or docker-compose.yml directly as bin/build will be using bin/vars to make sure that those two files are consistent with one another.
5. bin/build will re-generate Dockerfile and docker-compose.yml based on the contents of the two .template files and bin/vars. Note that this may take a really long time since it compiles Ruby from source. On an M2 Macbook Air, the entire process takes about an hour the first time. Once you have Ruby installed, changes to the Docker config after that in the file can be built much faster.
6. bin/start will start up whatever is in docker-compose.yml.
7. In another terminal window, bin/exec bash with run bash inside the image where Ruby and Rails are installed, effectively "logging you in" to the running container. You should be in /root/work, running as root and see all the files in this repo mirrored. If you run rails new my-app it will create a new app in this directory.

Inside the container, you can connect to Postgres like so:

> psql -Hdb -Upostgres -p5432 # password, when promted, is postgres
postgres=#

When you run Rails, you need to tell it to bind to 0.0.0.0, so you can't just do bin/rails c. Instead you must:

> bin/rails c -b0.0.0.0

When you do that, your Rails app should be available to your localhost on port 9000 (or whatever value you set in bin/vars for EXPOSE)

I wanted to be more explicit about what's being installed.

docker-compose.yml and Dockerfile share some values, but Docker provides no easy mechanism for that that I could figure out. So, the files are generated.

No reason, but Docker is a more generally useful skill to have.

Yup. You can set up NFS to make it much much faster. The only problem is that Webpack dev mode doesn't work. But that's probably fine because you should using only what JavaScript you need, right?