Generates release files and optional Dockerfile for release-based deployments.

The following release files are created:

• lib/app_name/release.ex - A release module containing tasks for running migrations inside a release

• rel/overlays/bin/migrate - A migrate script for conveniently invoking the release system migrations

• rel/overlays/bin/server - A server script for conveniently invoking the release system with environment variables to start the phoenix web server

Note, the rel/overlays directory is copied into the release build by default when running mix release.

To skip generating the migration-related files, use the --no-ecto flag. To force these migration-related files to be generated, use the --ecto flag.

Docker

When the --docker flag is passed, the following docker files are generated:

• Dockerfile - The Dockerfile for use in any standard docker deployment

• .dockerignore - A docker ignore file with standard elixir defaults

For extended release configuration, the mix release.init task can be used in addition to this task. See the Mix.Release docs for more details.

If you are using third party JS package managers like npm or yarn, you will need to update the generated Dockerfile with an extra step to fetch those packages. This might look like this:

...
ARG RUNNER_IMAGE="debian:..."

FROM node:20 as node
COPY assets assets
RUN cd assets && npm install

FROM ${BUILDER_IMAGE} as builder

...

COPY assets assets
COPY --from=node assets/node_modules assets/node_modules
...

If you are using esbuild through Node.js or other JavaScript build tools, the approach above can also be modified to invoke those in the node stage, for example:

FROM node:20 as node
COPY assets assets
RUN cd assets && npm install && node build.js --deploy

Note that you may need to adjust the assets.deploy task to not invoke Node.js again.