Git submodules and rebar

Question

My application uses Mochiweb. As I understand, `rebar` fetches the latest version from Github when I run `make`, because there is a line in `rebar.config`: ``` {deps, [ {mochiweb, ".*", {git, "git://github.com/mochi/mochiweb.git", "master"}} ``` My application has a VCS and it is git. So, essentially I have one git repository inside another: ``` myapp .git deps mochiweb .git src etc ``` I know that adding a git repository inside another one is not a good idea (`git add .`). Git submodules functionality should be used instead. So, I added the `deps/mochiweb` directory as a submodule to the main git repository. The problem is that when another developer clones the main repository he has to `init` and `update` the submodules first in order to get `deps/mochiweb` (otherwise it would be empty). If the developer just runs `make` right after he clones the main repository, the Makefile says the following: ``` ERROR: Dependency dir deps/mochiweb failed application validation with reason: {miss…

Accepted Answer

What is the proper way of adding another app to the deps of an Erlang app to allow easy updates by the other developers without using git submodules?

Add the app to the rebar.config and use:

```
./rebar update-deps
```

For updating. The first time, you need to use:

```
./rebar get-deps
```

See: https://github.com/basho/rebar/wiki/Rebar-commands

Now, back to your error.

My feeling is that you have an (almost) empty directory for mochiweb in your deps, probably as a result of playing with Git submodules. When you run the `get-deps` command, rebar silently discards mochiweb, since the directory is already there. But it expects an OTP application and looks for the `mochiweb.app` file, which is not there (the directory is empty). Therefore, the error. If my interpretation is correct, you can simply do:

```
rm -rf deps/mochiweb
./rebar get-deps
```

Having a look to your rebar.config would help, though.

Git submodules and rebar

Solution

Problem