Erlang.mk tries its best to be compatible with the other Erlang build tools. It can use dependencies written with other build tools in mind, and can also make your projects usable by those build tools as well. Erlang.mk is like the cool kid that gets along with everybody.
In this chapter I will use the term Rebar project to refer to a project built using Rebar 2, Rebar 3 or Mad. These three build tools are very similar and share the same configuration file.
Erlang.mk comes with a feature called Autoload which will use Rebar 2 to patch any Rebar project and make it compatible with Erlang.mk. This feature essentially patches Rebar out and adds a Makefile to the project that Erlang.mk can then use for building:
Autoload is documented in more details in the Packages and dependencies Chapter 7, Packages and dependencies chapter.
Erlang.mk projects can be made compatible with the Rebar family of build tools pretty easily, as Erlang.mk will generate all the files they require for building.
The Rebar family requires two files: a rebar.config file containing compilation options and the list of dependencies, and the application resource file, found either at ebin/$(PROJECT).app or at src/$(PROJECT).app.src.
Erlang.mk comes with a target that generates a rebar.config file when invoked:
$ make rebar.config
Careful! This will build the file even if it already existed before.
To build this file, Erlang.mk uses information it finds in
the DEPS and ERLC_OPTS variables, among others. This
means that the Rebar family builds your project much the
same way as Erlang.mk.
Careful though! Different build tools have different fetching strategies. If some applications provide differing dependencies, they might be fetched differently by other build tools. Check the upcoming Sanity check chapter to find out how to detect such issues.
You can automatically generate this file when you build
your application, by making it a dependency of the app
target:
app:: rebar.config
Don’t forget to commit the file when it changes!
If you run into other issues, it’s probably because you use a
feature specific to Erlang.mk, like the cp fetch method.
It could also be that we forgot to handle something! Sorry.
We are of course interested to hear about any compatibility
problems you may have, just open a ticket!
Erlang.mk has two ways to generate an application resource file: from the information found in the Makefile, or from the information found in the src/$(PROJECT).app.src file. Needless to say, if you have this file in your repository, then you don’t need to worry about compatibility with other build tools.
If you don’t, however, it’s not much harder. Every time Erlang.mk will compile your application, it will produce a new ebin/$(PROJECT).app file. Simply commit this file when it changes. It will only change when you modify the configuration, add or remove modules.