# mix docker
[](https://travis-ci.org/Recruitee/mix_docker)
Put your Elixir app inside minimal Docker image.
Based on [alpine linux](https://hub.docker.com/r/bitwalker/alpine-erlang/)
and [distillery](https://github.com/bitwalker/distillery) releases.
## Installation
1. Add `mix_docker` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[{:mix_docker, "~> 0.3.0"}]
end
```
2. Configure Docker image name
```elixir
# config/config.exs
config :mix_docker, image: "recruitee/hello"
```
3. Run `mix docker.init` to init distillery release configuration
4. Run `mix docker.build` & `mix docker.release` to build the image. See [Usage](#Usage) for more.
## Guides
- [Getting Started Tutorial](http://teamon.eu/2017/deploying-phoenix-to-production-using-docker/)
- [Setting up cluster with Rancher](http://teamon.eu/2017/setting-up-elixir-cluster-using-docker-and-rancher/)
- [Phoenix App Configuration Walkthrough](https://shovik.com/blog/8-deploying-phoenix-apps-with-docker)
## Usage
### Build a release
Run `mix docker.build` to build a release inside docker container
### Create minimal run container
Run `mix docker.release` to put the release inside minimal docker image
### Publish to docker registry
Run `mix docker.publish` to push newly created image to docker registry
### All three in one pass
Run `mix docker.shipit`
### Customize default Dockerfiles
Run `mix docker.customize`
## FAQ
#### How to configure my app?
Using ENV variables.
The provided Docker images contain `REPLACE_OS_VARS=true`, so you can use `"${VAR_NAME}"` syntax in `config/prod.exs`
like this:
```elixir
config :hello, Hello.Endpoint,
server: true,
url: [host: "${DOMAIN}"]
config :hello, Hello.Mailer,
adapter: Bamboo.MailgunAdapter,
api_key: "${MAILGUN_API_KEY}"
```
#### How to attach to running app using remote_console?
The easiest way is to `docker exec` into running container and run the following command,
where `CID` is the app container IO and `hello` is the name of your app.
```bash
docker exec -it CID /opt/app/bin/hello remote_console
```
#### How to install additional packages into build/release image?
First, run `mix docker.customize` to copy `Dockerfile.build` and `Dockerfile.release` into your project directory.
Now you can add whatever you like using standard Dockerfile commands.
Feel free to add some more apk packages or run some custom commands.
TIP: To keep the build process efficient check whether a given package is required only for
compilation (build) or runtime (release) or both.
#### How to move the Dockerfiles?
You can specify where to find the two Dockerfiles in the config.
```elixir
# config/config.exs
config :mix_docker,
dockerfile_build: "path/to/Dockerfile.build",
dockerfile_release: "path/to/Dockerfile.release"
```
The path is relative to the project root, and the files must be located inside
the root.
#### How to configure a Phoenix app?
To run a Phoenix app you'll need to install additional packages into the build image: run `mix docker.customize`.
Modify the `apk --no-cache --update add` command in the `Dockerfile.build` as follows (add `nodejs` and `python`):
```
# Install Elixir and basic build dependencies
RUN \
echo "@edge http://nl.alpinelinux.org/alpine/edge/community" >> /etc/apk/repositories && \
apk update && \
apk --no-cache --update add \
git make g++ \
nodejs python \
elixir@edge && \
rm -rf /var/cache/apk/*
```
Install nodejs dependencies and cache them by adding the following lines before the `COPY` command:
```
# Cache node deps
COPY package.json ./
RUN npm install
```
Build and digest static assets by adding the following lines after the `COPY` command:
```
RUN ./node_modules/brunch/bin/brunch b -p && \
mix phoenix.digest
```
Add the following directories to `.dockerignore`:
```
node_modules
priv/static
```
Remove `config/prod.secret.exs` file and remove a reference to it from `config/prod.exs`. Configure your app's secrets directly in `config/prod.exs` using the environment variables.
Make sure to add `server: true` to your app's Endpoint config.
Build the images and run the release image normally.
Check out [this post](https://shovik.com/blog/8-deploying-phoenix-apps-with-docker) for detailed walkthrough of the Phoenix app configuration.
