Since Mix does not support hot upgrades out of the box, it does not
create a `RELEASES` file by default. Here, we introduce functionality
similar to what `relx` does in order for that file to be generated.
fdc8d7237e/src/rlx_assemble.erl (L928-L948)
The `RELEASES` file, in its turn, is required for `nodetool` to work
properly, and `nodetool` is required for us to generate several
required config files using `hocon`. Since the `start{_clean}.boot`
file used by the files generated by Elixir must be explicitly defined
in the `RELEASE_LIB` `boot_var`, we apply a small patch in the
existing `nodetool` in order to inject that required parameter when
calling the escript.
This commit enables a minimal working build of EMQX release using
Mix. However, to properly start the release, several configuration
steps are still missing. A `mix_release.sh` script does a few hacks
to get the release built with Mix to start properly, by first assuming
that `make emqx` has been run prior to the release, ran once to
generate the `app.*.config` files, and then it copies that and some
other files to the expected places.
Also, `emqx_telemetry` hangs the start procedure because it thinks
it's in an official release and tries to make a request. We disable
it temporarily via config just to get a working build for now.
Thales Macedo Garitezi