Bazel protobuf and grpc go example

Step 0:

Start with the example files form: grpc-go

• examples/helloworld/greeter_client/main.go
• examples/helloworld/greeter_server/main.go
• examples/helloworld/helloworld/helloworld.proto

Setup your go modules and update imports to reflect changes:

$ go mod init github.com/physcat/bazel-grpc-go-example

Update imports for client and server go programs:

+       pb "github.com/physcat/bazel-grpc-go-example/helloworld"
-       pb "google.golang.org/grpc/examples/helloworld/helloworld"

Update the helloworld/helloworld.proto file go_package:

@@ -17,6 +17,7 @@ syntax = "proto3";
 option java_multiple_files = true;
 option java_package = "io.grpc.examples.helloworld";
 option java_outer_classname = "HelloWorldProto";
+option go_package = "github.com/physcat/bazel-grpc-go-example/helloworld";

Step 1:

Use go to find the latest version of the protobuf and grpc tools: (Here we use the go toolchain to help us later in step 3)

$ go get -u -v github.com/protocolbuffers/protobuf
$ go get -v -u google.golang.org/grpc

Step 2:

Setup bazel for gazelle

• Create WORKSPACE and base BUILD.bazel as per bazel-gazelle
• Use gazelle to update WORKSPACE file form go.mod

bazel run //:gazelle -- update-repos -from_file=go.mod

Step 3:

Check the bazebuild project rules_go under workspace

We need a repository called com_google_protobuf pointing to our new version of github.com/protocolbuffers/protobuf. Gazelle has already added this entry we just need to update it as below:

 go_repository(
-    name = "com_github_protocolbuffers_protobuf",
+    name = "com_google_protobuf",
     importpath = "github.com/protocolbuffers/protobuf",
     sum = "h1:D7TuYcQlt7ZiIgMqTuBJxvzPklWjyMhqav/sFpnx23Y=",
     version = "v3.11.4+incompatible",
 )
+
+load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")
+
+protobuf_deps()

We don't need anything extra for the grpc because of step 1 gazelle already added everything.

Step 4:

Now we are ready to let gazelle generate the build files:

bazel run //:gazelle

Step 5:

All ready just build using bazel. (first build may be slower)

$ bazel build //greeter_server:greeter_server
$ bazel build //greeter_client:greeter_client

And run from two different terminals:

Terminal 1

$ bazel-bin/greeter_server/linux_amd64_stripped/greeter_server
2020/04/06 22:02:19 Received: world

Terminal 2

$ bazel-bin/greeter_client/linux_amd64_stripped/greeter_client
2020/04/06 22:02:19 Greeting: Hello world