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Common code for GAPIC-generated API clients


>= 1.9, < 3.a
~> 1.59
>= 1.0, < 3.a
 Project Readme

API Client Generator for Ruby

Create Ruby clients from a protocol buffer description of an API.

Getting started

The easiest way to use this generator is to clone the github repo (either at HEAD or at a release tag) and run the generator using the provided command line tool. The following steps describe how do this.

Prepare your Ruby environment

The GAPIC Generator for Ruby is written in Ruby and requires the Ruby runtime and several related tools.

First, install Ruby, version 3.1 or later, if you have not already done so. This page on the official Ruby website includes installation information. We recommend using a Ruby version manager such as ASDF.

You will need the Bundler and Toys gems. Install them if you haven't done so already:

$ gem install bundler
$ gem install toys

Clone the Ruby GAPIC Generator repo

The generator itself is present in the repo https://github.com/googleapis/gapic-generator-ruby. Clone it to your local workstation. The following steps will use it at HEAD, but you can also check out a recent release tag.

$ git clone https://github.com/googleapis/gapic-generator-ruby.git
$ cd gapic-generator-ruby

There are submodules in this repo, so you will need to initialize those.

$ git submodule init
$ git submodule update

Generating the Showcase client

In this section we'll generate a client for the Showcase API, a sample API used for demoing and testing GAPIC.

(The following section will demonstrate how to generate a client for a Google API from the Googleapis repo.)

Obtain Showcase protos

The GAPIC Generator uses protobuf files as input. We will obtain the protos for Showcase from its repository on GitHub.

Clone the Showcase repo. For this example, we will assume we are starting inside the gapic-generator-ruby clone directory (see above). We'll move up one directory, clone the showcase repo and then move back into the gapic-generator-ruby directory for subsequent steps.

$ cd ..
$ git clone https://github.com/googleapis/gapic-showcase.git
$ cd gapic-generator-ruby

Configure the client for the Echo service

Each client requires a configuration. The Ruby GAPIC Generator can get this configuration from a YAML-formatted config file, or from the BUILD.bazel file used to generate Google APIs. For Showcase, we have neither, so we'll write a YAML file.

Create a file called showcase.yml and copy the following into it:

:transports: ["rest", "grpc"]
  :name: google-showcase

Note that all the keys begin with a colon, which signals to Ruby that they should be deserialized as Symbol keys rather than String keys.

Generate the Echo client

We can now run the generator, by using a Toys tool provided in the repo. This run will generate a client of the "Echo" service, one of the services in the Showcase API. It will read the source protos from the gapic-showcase clone, and write the result into a tmp directory within the gapic-generator-ruby clone. It will also get the configuration from the showcase.yml file you created above.

Make sure you have moved into the gapic-generator-ruby directory, then run:

$ toys run --input-dir=../gapic-showcase/schema --output-dir=tmp \
  --config-file=showcase.yml google/showcase/v1beta1/echo.proto

Now you can see the results in the tmp directory.

$ cd tmp
$ ls

Generating a client for Google Cloud Language V2

In this section we'll generate a client for the Natural Language service that is part of Google Cloud. This will be very similar to the above Showcase example, but we will get the input protos and configuration from the googleapis repository, which is brought into gapic-generator-ruby as a submodule.

Within the gapic-generator-ruby directory, run:

$ toys run --output-dir=tmp --clean google/cloud/language/v2

That's it! The generator's proto lookup defaults to searching the submodule in shared/googleapis so you do not need to provide --input-dir. It also finds its configuration in the BUILD.bazel file colocated with the protos. The --clean flag clears out the old tmp directory (in case you previously had generated the showcase client there.)


The Ruby GAPIC Generator is maintained internally at Google by the Ruby Cloud SDK team. The roadmap is generally driven by the needs of the Google API client libraries for Ruby. However, contributions will be considered. Before opening a pull request, please open an issue describing the change that you are proposing; unless it is an obvious or trivial fix, it is best to discuss and get agreement on the change before making it.


The CI runs on GitHub Actions and comprises four types of tests:

  • Unit tests for the various components
  • Comparative tests against golden outputs
  • Functional tests for some golden outputs
  • Lint and style checks using rubocop

To run the tests, execute this in the repo:

$ toys ci

Note that the functional tests require Docker because they involve spinning up a temporary service for a generated client to talk to.

Updating golden outputs

If you make changes that result in changes to the generated client code, you will need to regenerate the golden outputs to match. To do that, run the following in the repo:

$ toys gen

Include both the generator and golden output changes in the same pull request.

Golden outputs are generated from input protos in the shared/googleapis submodule. Their configurations are provided by YAML files in the shared/config directory. Finally, there is an index of those outputs in the shared/gem_defaults.rb file.

If any of these inputs are modified, or if the submodule is updated, you should update the "binary inputs" in the shared/input directory. These are binary encodings of that input and configuration data, used in some tests. To update the binary inputs, execute:

$ toys bin


While Google uses this product internally to produce API client libraries, this generator itself is not an official Google product. You can use it to produce your own clients for Google services or your own, but Google does not provide official support for use of this generator.