fix(metadata): gate metadata file-gen on a CLI flag (#684)

rules_java_gapic/java_gapic.bzl

@@ -158,11 +158,16 @@ def java_gapic_library(
     raw_srcjar_name = srcjar_name + "_raw"
     output_suffix = ".srcjar"
 
+    # Produces the GAPIC metadata file if this flag is set. to any value.
+    # Protoc invocation: --java_gapic_opt=metadata
+    plugin_args = ["metadata"]
+
     _java_generator_name = "java_gapic"
     proto_custom_library(
         name = raw_srcjar_name,
         deps = srcs,
         plugin = Label("@gapic_generator_java//:protoc-gen-%s" % _java_generator_name),
+        plugin_args = plugin_args,
         plugin_file_args = {},
         opt_file_args = file_args_dict,
         output_type = _java_generator_name,

src/main/java/com/google/api/generator/gapic/Generator.java

@@ -30,8 +30,7 @@ public static CodeGeneratorResponse generateGapic(CodeGeneratorRequest request)
     List<GapicClass> clazzes = Composer.composeServiceClasses(context);
     GapicPackageInfo packageInfo = Composer.composePackageInfo(context);
     String outputFilename = "temp-codegen.srcjar";
-    CodeGeneratorResponse response =
-        Writer.write(clazzes, packageInfo, context.gapicMetadata(), outputFilename);
+    CodeGeneratorResponse response = Writer.write(context, clazzes, packageInfo, outputFilename);
     return response;
   }
 }

src/main/java/com/google/api/generator/gapic/model/GapicContext.java

@@ -44,6 +44,8 @@ public abstract class GapicContext {
 
   public abstract ImmutableMap<String, ResourceName> helperResourceNames();
 
+  public abstract boolean gapicMetadataEnabled();
+
   public GapicMetadata gapicMetadata() {
     return gapicMetadata;
   }
@@ -74,7 +76,9 @@ static GapicMetadata defaultGapicMetadata() {
   public abstract Builder toBuilder();
 
   public static Builder builder() {
-    return new AutoValue_GapicContext.Builder().setMixinServices(Collections.emptyList());
+    return new AutoValue_GapicContext.Builder()
+        .setMixinServices(Collections.emptyList())
+        .setGapicMetadataEnabled(false);
   }
 
   @AutoValue.Builder
@@ -100,6 +104,8 @@ public Builder setHelperResourceNames(Set<ResourceName> helperResourceNames) {
 
     public abstract Builder setServiceYamlProto(com.google.api.Service serviceYamlProto);
 
+    public abstract Builder setGapicMetadataEnabled(boolean gapicMetadataEnabled);
+
     public abstract GapicContext build();
   }
 }

src/main/java/com/google/api/generator/gapic/protoparser/Parser.java

@@ -104,6 +104,8 @@ public static GapicContext parse(CodeGeneratorRequest request) {
     Optional<GapicLanguageSettings> languageSettingsOpt =
         GapicLanguageSettingsParser.parse(gapicYamlConfigPathOpt);
 
+    boolean willGenerateMetadata = PluginArgumentParser.hasMetadataFlag(request);
+
     Optional<String> serviceConfigPathOpt = PluginArgumentParser.parseJsonConfigPath(request);
     String serviceConfigPath = serviceConfigPathOpt.isPresent() ? serviceConfigPathOpt.get() : null;
     Optional<GapicServiceConfig> serviceConfigOpt = ServiceConfigParser.parse(serviceConfigPath);
@@ -179,6 +181,7 @@ public static GapicContext parse(CodeGeneratorRequest request) {
         .setResourceNames(resourceNames)
         .setHelperResourceNames(outputArgResourceNames)
         .setServiceConfig(serviceConfigOpt.isPresent() ? serviceConfigOpt.get() : null)
+        .setGapicMetadataEnabled(willGenerateMetadata)
         .setServiceYamlProto(serviceYamlProtoOpt.isPresent() ? serviceYamlProtoOpt.get() : null)
         .build();
   }

src/main/java/com/google/api/generator/gapic/protoparser/PluginArgumentParser.java

@@ -17,6 +17,7 @@
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Strings;
 import com.google.protobuf.compiler.PluginProtos.CodeGeneratorRequest;
+import java.util.Arrays;
 import java.util.Optional;
 
 // Parses the arguments from the protoc plugin.
@@ -27,6 +28,7 @@ public class PluginArgumentParser {
   // Synced to rules_java_gapic/java_gapic.bzl.
   @VisibleForTesting static final String KEY_GRPC_SERVICE_CONFIG = "grpc-service-config";
   @VisibleForTesting static final String KEY_GAPIC_CONFIG = "gapic-config";
+  @VisibleForTesting static final String KEY_METADATA = "metadata";
   @VisibleForTesting static final String KEY_SERVICE_YAML_CONFIG = "api-service-config";
 
   private static final String JSON_FILE_ENDING = "grpc_service_config.json";
@@ -45,6 +47,10 @@ static Optional<String> parseServiceYamlConfigPath(CodeGeneratorRequest request)
     return parseServiceYamlConfigPath(request.getParameter());
   }
 
+  static boolean hasMetadataFlag(CodeGeneratorRequest request) {
+    return hasMetadataFlag(request.getParameter());
+  }
+
   /** Expects a comma-separated list of file paths. */
   @VisibleForTesting
   static Optional<String> parseJsonConfigPath(String pluginProtocArgument) {
@@ -61,6 +67,11 @@ static Optional<String> parseServiceYamlConfigPath(String pluginProtocArgument)
     return parseArgument(pluginProtocArgument, KEY_SERVICE_YAML_CONFIG, SERVICE_YAML_FILE_ENDING);
   }
 
+  @VisibleForTesting
+  static boolean hasMetadataFlag(String pluginProtocArgument) {
+    return Arrays.stream(pluginProtocArgument.split(COMMA)).anyMatch(s -> s.equals(KEY_METADATA));
+  }
+
   private static Optional<String> parseArgument(
       String pluginProtocArgument, String key, String fileEnding) {
     if (Strings.isNullOrEmpty(pluginProtocArgument)) {

src/main/java/com/google/api/generator/gapic/protowriter/Writer.java

@@ -18,8 +18,8 @@
 import com.google.api.generator.engine.ast.PackageInfoDefinition;
 import com.google.api.generator.engine.writer.JavaWriterVisitor;
 import com.google.api.generator.gapic.model.GapicClass;
+import com.google.api.generator.gapic.model.GapicContext;
 import com.google.api.generator.gapic.model.GapicPackageInfo;
-import com.google.gapic.metadata.GapicMetadata;
 import com.google.protobuf.ByteString;
 import com.google.protobuf.compiler.PluginProtos.CodeGeneratorResponse;
 import com.google.protobuf.util.JsonFormat;
@@ -36,9 +36,9 @@ public GapicWriterException(String errorMessage) {
   }
 
   public static CodeGeneratorResponse write(
+      GapicContext context,
       List<GapicClass> clazzes,
       GapicPackageInfo gapicPackageInfo,
-      GapicMetadata gapicMetadata,
       String outputFilePath) {
     ByteString.Output output = ByteString.newOutput();
     JavaWriterVisitor codeWriter = new JavaWriterVisitor();
@@ -85,13 +85,15 @@ public static CodeGeneratorResponse write(
       throw new GapicWriterException("Could not write code for package-info.java");
     }
 
-    // Write the mdatadata file.
-    jarEntry = new JarEntry(String.format("%s/gapic_metadata.json", path));
-    try {
-      jos.putNextEntry(jarEntry);
-      jos.write(JsonFormat.printer().print(gapicMetadata).getBytes());
-    } catch (IOException e) {
-      throw new GapicWriterException("Could not write gapic_metadata.json");
+    if (context.gapicMetadataEnabled()) {
+      // Write the mdatadata file.
+      jarEntry = new JarEntry(String.format("%s/gapic_metadata.json", path));
+      try {
+        jos.putNextEntry(jarEntry);
+        jos.write(JsonFormat.printer().print(context.gapicMetadata()).getBytes());
+      } catch (IOException e) {
+        throw new GapicWriterException("Could not write gapic_metadata.json");
+      }
     }
 
     try {

src/test/java/com/google/api/generator/gapic/protoparser/PluginArgumentParserTest.java

@@ -16,12 +16,12 @@
 
 import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.assertFalse;
+import static junit.framework.Assert.assertTrue;
 
 import java.util.Arrays;
 import org.junit.Test;
 
 public class PluginArgumentParserTest {
-
   @Test
   public void parseJsonPath_onlyOnePresent() {
     String jsonPath = "/tmp/grpc_service_config.json";
@@ -225,6 +225,29 @@ public void parseServiceYamlPath_noneFound() {
     assertFalse(PluginArgumentParser.parseServiceYamlConfigPath(rawArgument).isPresent());
   }
 
+  @Test
+  public void parseMetadataFlag_noneFound() {
+    String jsonPath = "/tmp/foo_grpc_service_config.json";
+    String gapicPath = "";
+    String rawArgument =
+        String.join(",", Arrays.asList(createGrpcServiceConfig(jsonPath), gapicPath));
+    assertFalse(PluginArgumentParser.hasMetadataFlag(rawArgument));
+
+    // Wrong casing.
+    rawArgument =
+        String.join(",", Arrays.asList("Metadata", createGrpcServiceConfig(jsonPath), gapicPath));
+    assertFalse(PluginArgumentParser.hasMetadataFlag(rawArgument));
+  }
+
+  @Test
+  public void parseMetadataFlag_flagFound() {
+    String jsonPath = "/tmp/foo_grpc_service_config.json";
+    String gapicPath = "";
+    String rawArgument =
+        String.join(",", Arrays.asList("metadata", createGrpcServiceConfig(jsonPath), gapicPath));
+    assertTrue(PluginArgumentParser.hasMetadataFlag(rawArgument));
+  }
+
   private static String createGrpcServiceConfig(String path) {
     return String.format("%s=%s", PluginArgumentParser.KEY_GRPC_SERVICE_CONFIG, path);
   }