otelttrpc: lift over example from otelgrpc.

Lift over the sample client/server code from otelgrpc,
gutting out any bits we don't support yet (streaming),
and adapting it for (otel)ttrpc.

Signed-off-by: Krisztian Litkey <[email protected]>

example/Makefile

@@ -0,0 +1,86 @@
+#   Copyright The containerd Authors.
+
+#   Licensed under the Apache License, Version 2.0 (the "License");
+#   you may not use this file except in compliance with the License.
+#   You may obtain a copy of the License at
+
+#       http://www.apache.org/licenses/LICENSE-2.0
+
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the License is distributed on an "AS IS" BASIS,
+#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#   See the License for the specific language governing permissions and
+#   limitations under the License.
+
+GO_CMD   := go
+GO_BUILD := $(GO_CMD) build
+
+PROTO_SOURCES := $(shell find . -name '*.proto' | grep -v /vendor/)
+PROTO_GOFILES := $(patsubst %.proto,%.pb.go,$(PROTO_SOURCES)) \
+	         $(patsubst %.proto,%_ttrpc.pb.go,$(PROTO_SOURCES))
+PROTO_INCLUDE := -I$(PWD):/usr/local/include:/usr/include
+PROTO_OPTIONS := --proto_path=. $(PROTO_INCLUDE) \
+    --go_opt=paths=source_relative --go_out=. \
+    --go-ttrpc_opt=paths=source_relative --go-ttrpc_out=.
+PROTO_COMPILE := PATH=$(PATH):$(shell go env GOPATH)/bin; protoc $(PROTO_OPTIONS)
+
+INSTALL_PROTOC := https://github.com/containerd/containerd/blob/main/script/setup/install-protobuf
+PROTOC_DEPS    := google.golang.org/protobuf/cmd/[email protected]
+TTRPC_PLUGIN   := github.com/containerd/ttrpc/cmd/protoc-gen-go-ttrpc@74421d10189e8c118870d294c9f7f62db2d33ec1
+WGET           := wget
+
+BINARIES := example-client example-server
+
+ifneq ($(V),1)
+  Q := @
+endif
+
+
+#
+# top-level targets
+#
+
+all: build ## build example
+
+build: $(BINARIES)
+
+clean:
+	$(Q)rm -f $(BINARIES)
+
+protos: $(PROTO_GOFILES) ## generate example API ttrpc bindings
+
+#
+# binary compilation targets
+#
+
+example-client: $(wildcard api/*.go config/*.go client/*.go) ## build example client
+	$(Q)echo "Building $@..."; \
+	$(GO_BUILD) -o $@ ./client
+
+example-server: $(wildcard api/*.go config/*.go server/*.go) ## build example-server
+	$(Q)echo "Building $@..."; \
+	$(GO_BUILD) -o $@ ./server
+
+#
+# proto generation targets
+#
+
+%.pb.go: %.proto
+	$(Q)echo "Generating $@..."; \
+	$(PROTO_COMPILE) $<
+
+#
+# targets for installing dependencies
+#
+
+install-protoc install-protobuf: ## install protobuf compiler
+	$(Q)$(WGET) $(INSTALL_PROTOC) && chmod a+x install-protobuf && ./install-protobuf
+
+install-protoc-dependencies: ## install protobuf compiler dependencies
+	$(Q)$(GO_INSTALL) -mod=mod $(PROTOC_DEPS)
+
+install-ttrpc-plugin: ## install protobuf compiler ttrcp plugin
+	$(Q)$(GO_INSTALL) -mod=mod $(TTRPC_PLUGIN)
+
+help: ## this help
+	@awk 'BEGIN {FS = ":.*?## "} /^[a-zA-Z_-]+:.*?## / {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}' $(MAKEFILE_LIST) | sort

example/README.md

@@ -0,0 +1,33 @@
+# ttRPC Tracing Example
+
+Traces unary client and server calls via interceptors.
+
+### Compile Example Client and Server
+
+```sh
+make
+```
+
+### Run server
+
+```sh
+./example-server
+```
+
+### Run client
+
+```sh
+./example-client
+```
+
+### Generate Protobuf Go and ttRPC bindings
+
+If you modify the example protobuf definitions (`api/hello-service.proto`),
+you need to regenerate the corresponding golang/ttRPC bindings.
+
+```sh
+# Install protoc and its dependencies if you don't have them yet.
+make install-protoc install-protoc-dependencies install-ttrpc-plugin
+# Regenerate golang/ttRPC bindings, recompile client and server.
+make
+```

example/api/hello-service.proto

@@ -0,0 +1,30 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+package api;
+
+option go_package = "github.com/containerd/otelttrpc/example/api;api";
+
+service HelloService {
+  rpc SayHello (HelloRequest) returns (HelloResponse);
+}
+
+message HelloRequest {
+  string greeting = 1;
+}
+
+message HelloResponse {
+  string reply = 1;
+}