Deploy a Phoenix App with Distillery

This is a guide to deploying Phoenix projects on Render using Distillery.

We'll start off with a bare Phoenix project with Ecto, modify it to use Distillery, and deploy it on Render. The full source code for this tutorial is available at https://github.com/render-examples/phoenix-distillery.

Create a Phoenix App with Distillery

1. Create a new Phoenix app in the terminal:

2. Update mix.exs to add Distillery to deps:

   Then run mix deps.get in your terminal to update dependencies.

Configure Distillery

1. Let's configure Distillery for production. Update the Endpoint config in config/prod.exs so it looks like this:

   Read more about Distillery configuration.

   We're not going to check secrets into source control. Instead, we're going to manage them in production with Render environment variables. So let's delete the line at the end referring to prod.secret.exs.

   And delete the file config/prod.secret.exs.

2. You're now ready to initialize your Distillery release.

   This will create rel/config.exs, rel/vm.args, and the empty directory rel/plugins.

   rel/vm.args is used for runtime configuration by default, but we're going to use the Mix Config Provider instead so you can delete this file.

Creating a Mix Config Provider

1. Create a Mix configuration file at rel/config/config.exs:

   Contents of rel/config/config.exs :

   This sets up the Mix configuration provider to get values from runtime environment variables.

2. Update rel/config.exs to use your new provider. Change the environment :prod section in the file to this:

Configuring Ecto

Let's configure Ecto to get the DATABASE_URL from the environment. Change lib/phoenix_distillery/repo.ex so it looks like this:

Build a Release with Distillery

You're now ready to build and run your first release!

The output should look like this:

You can now test your release (assuming PostgreSQL is up on your local machine):

You can now deploy your app in production! 🎉

Deploying to Render

1. Create a build script called build.sh at the root of your repo:

   Make the script executable before checking it into Git:

2. Create a new PostgreSQL database on Render.

3. Create a new Web Service on Render, and give Render permission to access your new repo.

4. Use the following values during creation:

   Language	Elixir
   Build Command	./build.sh
   Start Command	./_render/bin/phoenix_distillery foreground

   Also add these environment variables to the web service:

   Key	Value
   SECRET_KEY_BASE	A sufficiently strong secret. You can generate a secret locally by running mix phx.gen.secret
   DATABASE_URL	The internal database URL of the database you created above.

   That's it! Your web service will be live on your Render URL as soon as the build finishes.

Going forward, every push to your repo will automatically build your app and deploy it in production. If the build fails, Render will automatically stop the deploy process and the existing version of your app will keep running until the next successful deploy.

Read about customizing Elixir and Erlang versions for your app.