feat: add ability to remove unversioned modules (#2329)

Author: parthea

gapic/generator/generator.py

@@ -244,6 +244,16 @@ def _render_template(
         if not opts.metadata and template_name.endswith("gapic_metadata.json.j2"):
             return answer
 
+        # Disables generation of an unversioned Python package for this client
+        # library. This means that the module names will need to be versioned in
+        # import statements. For example `import google.cloud.library_v2` instead
+        # of `import google.cloud.library`.
+        if template_name.startswith("%namespace/%name/") and \
+                api_schema.all_library_settings[
+                    api_schema.naming.proto_package
+                ].python_settings.experimental_features.unversioned_package_disabled:
+            return answer
+
         # Quick check: Rendering per service and per proto would be a
         # combinatorial explosion and is almost certainly not what anyone
         # ever wants. Error colorfully on it.

gapic/templates/setup.py.j2

@@ -1,5 +1,6 @@
 {# TODO(https://github.com/googleapis/gapic-generator-python/issues/2121): Remove the following variable (and the condition later in this file) for async rest transport once support for it is GA. #}
 {% set rest_async_io_enabled = api.all_library_settings[api.naming.proto_package].python_settings.experimental_features.rest_async_io_enabled %}
+{% set unversioned_package_disabled = api.all_library_settings[api.naming.proto_package].python_settings.experimental_features.unversioned_package_disabled %}
 {% extends '_base.py.j2' %}
 {% from '_pypi_packages.j2' import pypi_packages %}
 {% block content %}
@@ -15,8 +16,8 @@ package_root = os.path.abspath(os.path.dirname(__file__))
 name = '{{ api.naming.warehouse_package_name }}'
 
 {% set warehouse_description = api.naming.warehouse_package_name.replace('-',' ')|title %}
-{% set package_path = api.naming.module_namespace|join('/') + "/" + api.naming.module_name %}
 
+{% set package_path = api.naming.module_namespace|join('/') + "/" + (api.naming.versioned_module_name if unversioned_package_disabled else api.naming.module_name) %}
 description = "{{ warehouse_description }} API client library"
 
 version = None

tests/integration/eventarc_v1.yaml

@@ -115,4 +115,12 @@ authentication:
   - selector: 'google.longrunning.Operations.*'
     oauth:
       canonical_scopes: |-
-        https://www.googleapis.com/auth/cloud-platform
+        https://www.googleapis.com/auth/cloud-platform
+
+
+publishing:
+  library_settings:
+  - version: 'google.cloud.eventarc.v1'
+    python_settings:
+      experimental_features:
+        unversioned_package_disabled: true

tests/integration/goldens/eventarc/google/cloud/eventarc/__init__.py

@@ -28,7 +28,7 @@
 
 version = None
 
-with open(os.path.join(package_root, 'google/cloud/eventarc/gapic_version.py')) as fp:
+with open(os.path.join(package_root, 'google/cloud/eventarc_v1/gapic_version.py')) as fp:
     version_candidates = re.findall(r"(?<=\")\d+.\d+.\d+(?=\")", fp.read())
     assert (len(version_candidates) == 1)
     version = version_candidates[0]