Rebar3 gpb plugin
=====
[](https://travis-ci.org/lrascao/rebar3_gpb_plugin)
A rebar3 plugin for automatically compiling .proto files using the gpb protobuf compiler
Build
-----
$ rebar3 compile
Use
---
Add the plugin to your rebar config:
```erlang
{erl_opts, [{i, "./_build/default/plugins/gpb/include"}]}.
{plugins, [
{ rebar3_gpb_plugin, "2.0.0" }
]}.
```
Configure gpb options (example below), full list can consulted on [gpb's project page](https://github.com/tomas-abrahamsson/gpb) [gpb_compile:file/2](https://github.com/tomas-abrahamsson/gpb/blob/3.19.0/src/gpb_compile.erl#L66-L93):
```erlang
{gpb_opts, [
{i, "path/to/proto_dir"},
{module_name_suffix, "_pb"},
%{o, "path/to/out_dir"}, %% both .erl and .hrl are generated here
{o_erl, "path/to/out_src"},
{o_hrl, "path/to/out_include"},
{strings_as_binaries, true},
type_specs]}.
```
The `i`, `o_erl` and `o_hrl` option values are relative to the app's location.
Default values are:
* `{i, "proto"}`
* `{o_erl, "src"}`
* `{o_hrl, "include"}`
Plugin specific options (can be used together the gpb ones):
```erlang
{gpb_opts, [
{recursive, boolean()},
{ipath, "path/to/another/proto_dir"}
]}.
```
* `{recursive, boolean()}` - look recursively through the provided folders
to look for .proto files (default is true)
* `{ipath, "path/to/another/proto_dir"}` - paths that are to be added to gpb's
include path but not searched for .proto files (useful for importing .proto
files from other .proto).
Add the gpb include path (environment tipically is default):
{erl_opts, [{i, "./_build/<environment>/plugins/gpb/include"}]}.
Add a hook to automatically generate modules for your protobuf files and clean them afterwards:
```erlang
{provider_hooks, [
{pre, [
{compile, {protobuf, compile}},
{clean, {protobuf, clean}}
]}
]}.
```
Usage with umbrella projects
----------------------------
When using the gpb plugin with umbrella projects (aka having a `apps/<project>` structure) the `gpb_opts` and `provider_hooks` should **not** be in the top level `rebar.config`! Doing so would lead to undesired behavior and problems like code files not being compiled.
The solution is to create `apps/<project>/rebar.config` and specify `gpb_opts` and `provider_hooks` in this instead of the top level config. An example config would look like this:
```erlang
%% -*- erlang -*-
%%-------------------------------------------------------------------
%% GPB
%%-------------------------------------------------------------------
{gpb_opts, [
{i, "proto"},
{module_name_suffix, "_pb"},
{o_erl, "src"},
{o_hrl, "include"},
{strings_as_binaries, true},
type_specs]}.
{provider_hooks,
[{pre, [
{compile, {protobuf, compile}},
{clean, {protobuf, clean}}
]}
]}.
```
More examples
-------------
Complete usage examples are located in [doc/samples](/doc/samples).
