== Releases

Erlang.mk relies on _Relx_ for generating releases. This
chapter covers the Erlang.mk-specific bits. Consult the
https://erlware.github.io/relx/[Relx website] for more information.

=== Setup

Erlang.mk will create a release if it detects a Relx configuration
file in the '$(RELX_CONFIG)' location. This defaults to
'$(CURDIR)/relx.config'. You can override it by defining
the variable before including Erlang.mk:

[source,make]
RELX_CONFIG = $(CURDIR)/webchat.config

Relx does not need to be installed. Erlang.mk will download
and build it automatically.
// @todo We are going to fetch relx from repository in the future.

The Relx executable will be saved in the '$(RELX)' file. This
location defaults to '$(CURDIR)/relx' and can be overriden.

// @todo You can use a custom repository by ???

=== Configuration

You can specify additional Relx options using the `RELX_OPTS`
variable. For example, to enable `dev_mode`:

[source,make]
RELX_OPTS = -d true

While you can specify the output directory for the release
in the Relx options directly, Erlang.mk provides a specific
variable for it: `RELX_OUTPUT_DIR`. It defaults to the '_rel'
directory. You can also override it:

[source,make]
RELX_OUTPUT_DIR = /path/to/staging/directory

=== Generating the release

Now that you're all set, all you need to do is generate the
release. As mentioned before, Erlang.mk will automatically
generate it when it detects the '$(RELX_CONFIG)' file. This
means the following command will also build the release:

[source,bash]
$ make

If you need to generate the release, and only the release,
the `rel` target can be used:

[source,bash]
$ make rel

=== Running the release

Erlang.mk provides a convenience function for running the
release with one simple command:

[source,bash]
$ make run

This command will also build the project and generate the
release if they weren't already. It starts the release in
_console mode_, meaning you will also have a shell ready to
use to check things as needed.