README.md

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:

{erl_opts, [{i, "./_build/default/plugins/gpb/include"}]}.

{plugins, [
    { rebar3_gpb_plugin, "2.22.6" }
]}.

Configure gpb options (example below), full list can consulted on gpb's project page gpb_compile:file/2:

{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):

{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 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//plugins/gpb/include"}]}.

Add a hook to automatically generate modules for your protobuf files and clean them afterwards:

{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 -*-

%%-------------------------------------------------------------------
%% 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.