# DockerDistiller

This package uses Distillery and Docker to create containerized
builds of Elixir apps that are small and nimble.

To that end, it uses Alpine Linux as a base container OS and
[Marlus Saraiva's Great Work](https://github.com/msaraiva/alpine-erlang) on
keeping current versions of Erlang and Elixir for Alpine/Docker.

## Installation/Use

If [available in Hex](https://hex.pm/docs/publish), the package can be installed as:

  1. Add `docker_distiller` to your list of dependencies in `mix.exs`:

    ```elixir
    def deps do
      [{:docker_distiller, "~> 0.1.0"}]
    end
    ```

  1. Run `mix release.init` to get a Distillery config setup. See the [Distillery
     Docs](https://hexdocs.pm/distillery/getting-started.html) for details.

  1. Add a target `docker_repo` setting to your application.

  1. Add a template Dockerfile called `Dockerfile.deploy.eex`. This template will get
     stuff injected from the build and then written as `Dockerfile`, overwriting
     existing things. Currently only one thing is sent to the template:

     * `dist_tar`: the path of the distribution tarball.

     An example minimal template:

     ```
     FROM msaraiva/erlang:18.3

     ADD <%= dist_tar %> /webadminapistub

     CMD /yourapp/bin/yourapp foreground
     ```

     Note that even though the distribution tar contains Erlang, there are packages that
     Erlang needs (like the libncurses) so building from a basic Alpine image will most
     likely not work.

  1. Run `mix publish` to build a release and publish it.