chore: make generator version an optional param

.github/scripts/hermetic_library_generation.sh

@@ -90,6 +90,9 @@ fi
 git show "${target_branch}":"${generation_config}" > "${baseline_generation_config}"
 config_diff=$(diff "${generation_config}" "${baseline_generation_config}" || true)
 
+generator_version=$(mvn help:evaluate -Dexpression=project.version -q -DforceStdout -pl gapic-generator-java)
+echo "Local generator version: ${generator_version}"
+
 # install generator locally since we're using a SNAPSHOT version.
 mvn -V -B -ntp clean install -DskipTests
 
@@ -104,6 +107,7 @@ docker run \
   -u "$(id -u):$(id -g)" \
   -v "$(pwd):${workspace_name}" \
   -v "$HOME"/.m2:/home/.m2 \
+  -e GENERATOR_VERSION="${generator_version}" \
   gcr.io/cloud-devrel-public-resources/java-library-generation:"${image_tag}" \
   --baseline-generation-config-path="${workspace_name}/${baseline_generation_config}" \
   --current-generation-config-path="${workspace_name}/${generation_config}"

generation_config.yaml

@@ -1,4 +1,3 @@
-gapic_generator_version: 2.42.1-SNAPSHOT # {x-version-update:gapic-generator-java:current}
 googleapis_commitish: 7160b0c31e9b99fe896d1fa29b6fe6cfbf42588f
 # the libraries are ordered with respect to library name, which is
 # java-{library.library_name} or java-{library.api-shortname} when

library_generation/README.md

@@ -93,7 +93,7 @@ They are shared by library level parameters.
 
 | Name                    | Required | Notes                                        |
 |:------------------------|:--------:|:---------------------------------------------|
-| gapic_generator_version |   Yes    |                                              |
+| gapic_generator_version |    No    | set through env variable if not specified    |
 | protoc_version          |    No    | inferred from the generator if not specified |
 | grpc_version            |    No    | inferred from the generator if not specified |
 | googleapis-commitish    |   Yes    |                                              |

library_generation/model/generation_config.py

@@ -12,6 +12,8 @@
 # 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.
+import os
+
 import yaml
 from typing import Optional
 from library_generation.model.library_config import LibraryConfig
@@ -23,6 +25,7 @@
 COMMON_PROTOS_LIBRARY_NAME = "common-protos"
 GAPIC_GENERATOR_VERSION = "gapic_generator_version"
 LIBRARIES_BOM_VERSION = "libraries_bom_version"
+GENERATOR_VERSION_ENV_KEY = "GENERATOR_VERSION"
 
 
 class GenerationConfig:
@@ -32,18 +35,20 @@ class GenerationConfig:
 
     def __init__(
         self,
-        gapic_generator_version: str,
         googleapis_commitish: str,
         libraries: list[LibraryConfig],
+        gapic_generator_version: Optional[str] = None,
         libraries_bom_version: Optional[str] = None,
         grpc_version: Optional[str] = None,
         protoc_version: Optional[str] = None,
     ):
-        self.gapic_generator_version = gapic_generator_version
         self.googleapis_commitish = googleapis_commitish
         self.libraries_bom_version = (
             libraries_bom_version if libraries_bom_version else ""
         )
+        self.gapic_generator_version = GenerationConfig.__set_generator_version(
+            gapic_generator_version
+        )
         self.libraries = libraries
         self.grpc_version = grpc_version
         self.protoc_version = protoc_version
@@ -76,6 +81,21 @@ def contains_common_protos(self) -> bool:
                     break
         return self.__contains_common_protos
 
+    @staticmethod
+    def __set_generator_version(gapic_generator_version: Optional[str]) -> str:
+        if gapic_generator_version is not None:
+            return gapic_generator_version
+        # if the generator version is not set through generation config,
+        # get it from environment variable.
+        gapic_generator_version = os.getenv(GENERATOR_VERSION_ENV_KEY)
+        if not gapic_generator_version:
+            raise ValueError(
+                f"Environment variable {GENERATOR_VERSION_ENV_KEY}"
+                f" is not set when the generator version is not"
+                f" specified in the generation config."
+            )
+        return gapic_generator_version
+
     def __validate(self) -> None:
         seen_library_names = dict()
         for library in self.libraries:
@@ -148,12 +168,10 @@ def from_yaml(path_to_yaml: str) -> GenerationConfig:
         parsed_libraries.append(new_library)
 
     parsed_config = GenerationConfig(
-        gapic_generator_version=__required(
-            config, GAPIC_GENERATOR_VERSION, REPO_LEVEL_PARAMETER
-        ),
         googleapis_commitish=__required(
             config, "googleapis_commitish", REPO_LEVEL_PARAMETER
         ),
+        gapic_generator_version=__optional(config, GAPIC_GENERATOR_VERSION, None),
         grpc_version=__optional(config, "grpc_version", None),
         protoc_version=__optional(config, "protoc_version", None),
         libraries_bom_version=__optional(config, LIBRARIES_BOM_VERSION, None),

library_generation/test/model/generation_config_unit_tests.py

@@ -53,6 +53,24 @@ def test_generation_config_default_value(self):
         )
         self.assertEqual("", config.libraries_bom_version)
 
+    def test_generation_config_with_generator_version_env_raise_exception(self):
+        self.assertRaisesRegex(
+            ValueError,
+            "Environment variable GENERATOR_VERSION is not set",
+            GenerationConfig,
+            googleapis_commitish="",
+            libraries=[],
+        )
+
+    def test_generation_config_set_generator_version_from_env(self):
+        os.environ["GENERATOR_VERSION"] = "1.2.3"
+        config = GenerationConfig(
+            googleapis_commitish="",
+            libraries=[],
+        )
+        self.assertEqual("1.2.3", config.gapic_generator_version)
+        os.environ.pop("GENERATOR_VERSION")
+
     def test_from_yaml_succeeds(self):
         config = from_yaml(f"{test_config_dir}/generation_config.yaml")
         self.assertEqual("2.34.0", config.gapic_generator_version)
@@ -160,14 +178,6 @@ def test_validate_with_duplicate_library_name_raise_exception(self):
             ],
         )
 
-    def test_from_yaml_without_gapic_generator_version_raise_exception(self):
-        self.assertRaisesRegex(
-            ValueError,
-            "Repo level parameter, gapic_generator_version",
-            from_yaml,
-            f"{test_config_dir}/config_without_generator.yaml",
-        )
-
     def test_from_yaml_without_googleapis_commitish_raise_exception(self):
         self.assertRaisesRegex(
             ValueError,