Benefits
- One-line setup and bootup:
docker-compose up. It creates the database, does the Dialyzer pre-work (if the project has Dialyxer installed), etc. - A true development-oriented config: Source code is mounted so that changes in the container appear on the host, and vice-versa.
- Fast re-builds because the
DOCKERFILEis written to help Docker cache the images. - Syncing with the Postgres startup delay.
- All the crappy little dependencies installed.
- No weird hacks.
Now the three files, followed by instructions and my comments (or jump straight to the GitHub Repo):
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| version: '3.2' | |
| services: | |
| db: | |
| image: postgres | |
| web: | |
| build: . | |
| volumes: | |
| - type: bind | |
| source: . | |
| target: /app | |
| ports: | |
| - "4000:4000" | |
| depends_on: | |
| - db | |
| command: | |
| - ./run.sh |
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| # Elixir + Phoenix | |
| FROM elixir:1.6.1 | |
| # Install debian packages | |
| RUN apt-get update | |
| RUN apt-get install --yes build-essential inotify-tools postgresql-client | |
| # Install Phoenix packages | |
| RUN mix local.hex --force | |
| RUN mix local.rebar --force | |
| RUN mix archive.install --force https://github.com/phoenixframework/archives/raw/master/phx_new.ez | |
| # Install node | |
| RUN curl -sL https://deb.nodesource.com/setup_6.x -o nodesource_setup.sh | |
| RUN bash nodesource_setup.sh | |
| RUN apt-get install nodejs | |
| WORKDIR /app | |
| EXPOSE 4000 |
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| #!/bin/sh | |
| # Adapted from Alex Kleissner's post, Running a Phoenix 1.3 project with docker-compose | |
| # https://medium.com/@hex337/running-a-phoenix-1-3-project-with-docker-compose-d82ab55e43cf | |
| set -e | |
| # Ensure the app's dependencies are installed | |
| mix deps.get | |
| # Prepare Dialyzer if the project has Dialyxer set up | |
| if mix help dialyzer >/dev/null 2>&1 | |
| then | |
| echo "\nFound Dialyxer: Setting up PLT..." | |
| mix do deps.compile, dialyzer --plt | |
| else | |
| echo "\nNo Dialyxer config: Skipping setup..." | |
| fi | |
| # Install JS libraries | |
| echo "\nInstalling JS..." | |
| cd assets && npm install | |
| cd .. | |
| # Wait for Postgres to become available. | |
| until psql -h db -U "postgres" -c '\q' 2>/dev/null; do | |
| >&2 echo "Postgres is unavailable - sleeping" | |
| sleep 1 | |
| done | |
| echo "\nPostgres is available: continuing with database setup..." | |
| # Potentially Set up the database | |
| mix ecto.create | |
| mix ecto.migrate | |
| echo "\nTesting the installation..." | |
| # "Proove" that install was successful by running the tests | |
| mix test | |
| echo "\n Launching Phoenix web server..." | |
| # Start the phoenix web server | |
| mix phx.server |
How to Dockerize a Phoenix app
- Copy the three config files to the root folder of an existing Phoenix project. Make
run.shexecutable, e.g.:chmod +x run.sh. - Edit your development database settings to connect to Postgres at host
db, usernamepostgres, password is an empty string. - Spin it up with
docker-compose up.
The Phoenix app should be up and running at http://localhost:4000. Something like this:
Now a little about this configuration
It’s the result of several hours spent fine-tuning it and going through the Docker file references. I wanted a “online-liner” container-based dev environment. To get this, I started with a Rails Docker config and got a boost from this excellent post by Alex Kleissner. He had the nice idea of a run.sh script to do some things like synchronize Phoenix and Postgres.
Also available as a GitHub repo. I have a very similar config for my Rails work as well.
Dogweather 