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, "2.23.2" }
]}.
```
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://hexdocs.pm/gpb/gpb_compile.html#file-2):
```erlang
{gpb_opts, [
{i, "path/to/proto_dir"} | {i, {deps, "relative/path/from/deps/to/proto_dir"}},
{f, ["desired_proto_file1.proto"]},
{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"} | {ipath, {deps, "path/from/deps/dir/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).
* `{i, {deps, "relative/path/from/deps/to/proto_dir"}}` - allows you to compile
proto files that were declared and fetched as app dependencies, the [rebar_raw_resource](https://github.com/basho/rebar_raw_resource)
plugin is a good fit for this use case.
* `{ipath, {deps, "relative/path/from/deps/to/proto_dir"}}` - allows you to specify
proto include paths in the same fashion as the `{i, {deps, _}}` directive.
* `{f, ["file1.proto", "file2.proto"]} - allows you to specify a subset of all proto files found.
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).
