protobuf-two-ways

This repository demonstrates two ways of using Go's new protobuf API to extend your protobufs and make them more powerful:

1. Code generation at compile-time, with protogen — code in go/plugin/
2. Reflection at runtime, with protoreflect — code in go/reflect/

This also demonstrates building protobufs with Bazel, which makes invoking protoc (the protobuf compiler) a smooth part of the development workflow. See protos/ and BUILD.bazel files throughout this repo for details.

For more details

Read more details about this in the corresponding blog post on eggybits.com.

To run and build as-written

Install Bazelisk

Set up bazelisk:

# if on a Mac
brew tap bazelbuild/tap
brew install bazelisk

Verify that bazel points to bazelisk:

$ which bazel
/usr/local/bin/bazel
melinda at xmbp in ~/code/eggybytes/protobuf-two-ways on ml-add-readme*
$ ls -l /usr/local/bin/bazel
lrwxr-xr-x  1 melinda  admin  34 Dec  2 11:33 /usr/local/bin/bazel -> ../Cellar/bazelisk/1.7.3/bin/bazel

Build everything

To build every target defined in this repo with Bazel, run:

bazel build //...

Test everything

To run every test target defined in this repo with Bazel (there's only one right now), run:

bazel test //...

Inspect generated files

In bazel-out/<your_architecture>/bin/protos/todo/todo_grpc_go_library_/protos/todo, you'll find:

• todo.pb.go: standard protoc-gen-go output
• todo_grpc.pb.go: standard protoc-gen-grpc output
• todo.pb.custom.go: our custom code output

todo.pb.custom.go should now look like:

package todo

import (
	context "context"
	mock "github.com/stretchr/testify/mock"
	grpc "google.golang.org/grpc"
)

//             ████
//           ██░░░░██
//         ██░░░░░░░░██
//         ██░░░░░░░░██
//       ██░░░░░░░░░░░░██
//       ██░░  ░░░░  ░░██
//       ██░░░░    ░░░░██
//         ██░░░░░░░░██
//           ████▓▓██

// MockEggDeliveryServiceClient is a mock EggDeliveryServiceClient which
// satisfies the EggDeliveryServiceClient interface.
type MockEggDeliveryServiceClient struct {
	mock.Mock
}

func NewMockEggDeliveryServiceClient() *MockEggDeliveryServiceClient {
	return &MockEggDeliveryServiceClient{}
}

func (c *MockEggDeliveryServiceClient) OrderEgg(ctx context.Context, in *OrderEggRequest, opts ...grpc.CallOption) (*OrderEggResponse, error) {
	args := c.Called(ctx, in)
	if args.Get(0) == nil {
		return nil, args.Error(1)
	}
	return args.Get(0).(*OrderEggResponse), args.Error(1)
}