chore(librariangen): introduce message package and add ReleaseInitRequest

The message packages hosts the data types that are common across
the CLI and language container implementations.
ReleaseInitRequest and ReleaseInitResponse are example data types
that belong to the package.

The request and response types are the argument and return type
of the upcoming ReleaseInit function implementation.

It was originally "request" package in google-cloud-go. However,
because it also includes responses from the language container to
the CLI, I'm renaming it to "messages".

Author: suztomo

internal/librariangen/generate/generator.go

@@ -27,15 +27,15 @@ import (
 
 	"cloud.google.com/java/internal/librariangen/bazel"
 	"cloud.google.com/java/internal/librariangen/execv"
+	"cloud.google.com/java/internal/librariangen/message"
 	"cloud.google.com/java/internal/librariangen/protoc"
-	"cloud.google.com/java/internal/librariangen/request"
 )
 
 // Test substitution vars.
 var (
 	bazelParse   = bazel.Parse
 	execvRun     = execv.Run
-	requestParse = request.ParseLibrary
+	requestParse = message.ParseLibrary
 	protocBuild  = protoc.Build
 )
 
@@ -113,7 +113,7 @@ func Generate(ctx context.Context, cfg *Config) error {
 // invokeProtoc handles the protoc GAPIC generation logic for the 'generate' CLI command.
 // It reads a request file, and for each API specified, it invokes protoc
 // to generate the client library. It returns the module path and the path to the service YAML.
-func invokeProtoc(ctx context.Context, cfg *Config, generateReq *request.Library) error {
+func invokeProtoc(ctx context.Context, cfg *Config, generateReq *message.Library) error {
 	for _, api := range generateReq.APIs {
 		apiServiceDir := filepath.Join(cfg.SourceDir, api.Path)
 		slog.Info("processing api", "service_dir", apiServiceDir)
@@ -135,7 +135,7 @@ func invokeProtoc(ctx context.Context, cfg *Config, generateReq *request.Library
 // readGenerateReq reads generate-request.json from the librarian-tool input directory.
 // The request file tells librariangen which library and APIs to generate.
 // It is prepared by the Librarian tool and mounted at /librarian.
-func readGenerateReq(librarianDir string) (*request.Library, error) {
+func readGenerateReq(librarianDir string) (*message.Library, error) {
 	reqPath := filepath.Join(librarianDir, "generate-request.json")
 	slog.Debug("librariangen: reading generate request", "path", reqPath)
 
@@ -264,4 +264,4 @@ func unzip(src, dest string) error {
 		}
 	}
 	return nil
-}
+}

internal/librariangen/request/request.go internal/librariangen/message/message.gointernal/librariangen/request/request.go renamed to internal/librariangen/message/message.go

@@ -12,14 +12,30 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package request
+// Package message defines data types which the Librarian CLI and language
+// containers exchange.
+// There shouldn't be CLI-specific data type or language container-specific
+// data types in this package.
+// TODO(b/447404382): Move this package to the https://github.com/googleapis/librarian
+// GitHub repository once the interface is finalized.
+package message
 
 import (
 	"encoding/json"
 	"fmt"
 	"os"
 )
 
+// Request is the structure of the release-init-request.json file.
+type ReleaseInitRequest struct {
+	Libraries []*Library `json:"libraries"`
+}
+
+// Response is the structure of the release-init-response.json file.
+type ReleaseInitResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // Library is the combination of all the fields used by CLI requests and responses.
 // Each CLI command has its own request/response type, but they all use Library.
 type Library struct {
@@ -75,4 +91,4 @@ func ParseLibrary(path string) (*Library, error) {
 	}
 
 	return &req, nil
-}
+}

…nal/librariangen/request/request_test.go …nal/librariangen/message/message_test.gointernal/librariangen/request/request_test.go renamed to internal/librariangen/message/message_test.go internal/librariangen/request/request_test.go renamed to internal/librariangen/message/message_test.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package request
+package message
 
 import (
 	"os"
@@ -95,4 +95,4 @@ func TestParseLibrary_FileNotFound(t *testing.T) {
 	if err == nil {
 		t.Error("Parse() expected error for non-existent file, got nil")
 	}
-}
+}