feat: read content of generate request (#14113)

Closes #14122

Author: ohmayr

.generator/Dockerfile

@@ -34,11 +34,10 @@ RUN apt-get update && \
     rm -rf /var/lib/apt/lists/*
 
 # Set up environment variables for tool versions to make updates easier.
-# TODO(): Downgrade to Python `3.11` if `3.13.5` is incompatible with googleapis. 
-ENV PYTHON_VERSION=3.13.5
+ENV PYTHON_VERSION=3.11.5
 
 # Create a symbolic link for `python3` to point to our specific version.
-ENV PATH /usr/local/bin/python3.13:$PATH
+ENV PATH /usr/local/bin/python3.11:$PATH
 
 # Install Python from source
 RUN wget https://www.python.org/ftp/python/${PYTHON_VERSION}/Python-${PYTHON_VERSION}.tgz && \
@@ -64,8 +63,7 @@ WORKDIR /app
 # TODO(https://github.com/googleapis/librarian/issues/906): Clone googleapis and run bazelisk build.
 
 # Copy the CLI script into the container and set ownership.
-# No other files or dependencies are needed for this simple script.
-COPY cli.py .
+COPY .generator/cli.py .
 
 # Set the entrypoint for the container to run the script.
-ENTRYPOINT ["python3.13", "./cli.py"]
+ENTRYPOINT ["python3.11", "./cli.py"]

.generator/cli.py

@@ -13,32 +13,88 @@
 # limitations under the License.
 
 import argparse
+import json
+import logging
+import os
 import sys
 
-def handle_configure(dry_run=False):
-    # TODO(https://github.com/googleapis/librarian/issues/466): Implement configure command.
-    print("'configure' command executed.")
+logger = logging.getLogger()
 
-def handle_generate(dry_run=False):
-    # TODO(https://github.com/googleapis/librarian/issues/448): Implement generate command.
-    print("'generate' command executed.")
+LIBRARIAN_DIR = "librarian"
+GENERATE_REQUEST_FILE = "generate-request.json"
 
-def handle_build(dry_run=False):
-    # TODO(https://github.com/googleapis/librarian/issues/450): Implement build command.
-    print("'build' command executed.")
+
+def _read_json_file(path):
+    """Helper function that reads a json file path and returns the loaded json content.
+
+    Args:
+        path (str): The file path to read.
+
+    Returns:
+        dict: The parsed JSON content.
+
+    Raises:
+        FileNotFoundError: If the file is not found at the specified path.
+        json.JSONDecodeError: If the file does not contain valid JSON.
+        IOError: If there is an issue reading the file.
+    """
+    with open(path, "r") as f:
+        return json.load(f)
+
+
+def handle_configure():
+    # TODO(https://github.com/googleapis/librarian/issues/466): Implement configure command and update docstring.
+    logger.info("'configure' command executed.")
+
+
+def handle_generate():
+    """The main coordinator for the code generation process.
+
+    This function orchestrates the generation of a client library by reading a
+    `librarian/generate-request.json` file, determining the necessary Bazel rule for each API, and
+    (in future steps) executing the build.
+
+    Raises:
+        ValueError: If the `generate-request.json` file is not found or read.
+    """
+
+    # Read a generate-request.json file
+    try:
+        request_data = _read_json_file(f"{LIBRARIAN_DIR}/{GENERATE_REQUEST_FILE}")
+    except Exception as e:
+        raise ValueError(
+            f"failed to read {LIBRARIAN_DIR}/{GENERATE_REQUEST_FILE}"
+        ) from e
+
+    logger.info(json.dumps(request_data, indent=2))
+
+    # TODO(https://github.com/googleapis/librarian/issues/448): Implement generate command and update docstring.
+    logger.info("'generate' command executed.")
+
+
+def handle_build():
+    # TODO(https://github.com/googleapis/librarian/issues/450): Implement build command and update docstring.
+    logger.info("'build' command executed.")
 
 
 if __name__ == "__main__":
     parser = argparse.ArgumentParser(description="A simple CLI tool.")
-    subparsers = parser.add_subparsers(dest="command", required=True, help="Available commands")
+    subparsers = parser.add_subparsers(
+        dest="command", required=True, help="Available commands"
+    )
 
     # Define commands
+    handler_map = {
+        "configure": handle_configure,
+        "generate": handle_generate,
+        "build": handle_build,
+    }
+
     for command_name, help_text in [
         ("configure", "Onboard a new library or an api path to Librarian workflow."),
         ("generate", "generate a python client for an API."),
-        ("build", "Run unit tests via nox for the generated library.")
+        ("build", "Run unit tests via nox for the generated library."),
     ]:
-        handler_map = {"configure": handle_configure, "generate": handle_generate, "build": handle_build}
         parser_cmd = subparsers.add_parser(command_name, help=help_text)
         parser_cmd.set_defaults(func=handler_map[command_name])
 
@@ -47,4 +103,4 @@ def handle_build(dry_run=False):
         sys.exit(1)
 
     args = parser.parse_args()
-    args.func(args)
+    args.func()

.generator/requirements-test.in

@@ -0,0 +1,16 @@
+# Copyright 2025 Google LLC
+#
+# 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.
+
+pytest
+pytest-mock

.generator/test_cli.py

@@ -12,17 +12,105 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from cli import handle_generate, handle_build, handle_configure
+import os
+import pytest
+import json
+import logging
 
+from unittest.mock import mock_open
 
-def test_handle_configure_dry_run():
-    # This is a simple test to ensure that the dry run command succeeds.
-    handle_configure(dry_run=True)
+from cli import (
+    _read_json_file,
+    handle_generate,
+    handle_build,
+    handle_configure,
+    LIBRARIAN_DIR,
+    GENERATE_REQUEST_FILE,
+)
 
-def test_handle_generate_dry_run():
-    # This is a simple test to ensure that the dry run command succeeds.
-    handle_generate(dry_run=True)
 
-def test_handle_build_dry_run():
-    # This is a simple test to ensure that the dry run command succeeds.
-    handle_build(dry_run=True)
+@pytest.fixture
+def mock_generate_request_file(tmp_path, monkeypatch):
+    """Creates the mock request file at the correct path inside a temp dir."""
+    # Create the path as expected by the script: .librarian/generate-request.json
+    request_path = f"{LIBRARIAN_DIR}/{GENERATE_REQUEST_FILE}"
+    request_dir = tmp_path / os.path.dirname(request_path)
+    request_dir.mkdir()
+    request_file = request_dir / os.path.basename(request_path)
+
+    request_content = {
+        "id": "google-cloud-language",
+        "apis": [{"path": "google/cloud/language/v1"}],
+    }
+    request_file.write_text(json.dumps(request_content))
+
+    # Change the current working directory to the temp path for the test.
+    monkeypatch.chdir(tmp_path)
+    return request_file
+
+
+def test_handle_configure_success(caplog, mock_generate_request_file):
+    """
+    Tests the successful execution path of handle_configure.
+    """
+    caplog.set_level(logging.INFO)
+
+    handle_configure()
+
+    assert "'configure' command executed." in caplog.text
+
+
+def test_handle_generate_success(caplog, mock_generate_request_file):
+    """
+    Tests the successful execution path of handle_generate.
+    """
+    caplog.set_level(logging.INFO)
+
+    handle_generate()
+
+    assert "google-cloud-language" in caplog.text
+    assert "'generate' command executed." in caplog.text
+
+
+def test_handle_generate_fail(caplog):
+    """
+    Tests the failed to read `librarian/generate-request.json` file in handle_generates.
+    """
+    with pytest.raises(ValueError):
+        handle_generate()
+
+
+def test_handle_build_success(caplog, mock_generate_request_file):
+    """
+    Tests the successful execution path of handle_build.
+    """
+    caplog.set_level(logging.INFO)
+
+    handle_build()
+
+    assert "'build' command executed." in caplog.text
+
+
+def test_read_valid_json(mocker):
+    """Tests reading a valid JSON file."""
+    mock_content = '{"key": "value"}'
+    mocker.patch("builtins.open", mocker.mock_open(read_data=mock_content))
+    result = _read_json_file("fake/path.json")
+    assert result == {"key": "value"}
+
+
+def test_file_not_found(mocker):
+    """Tests behavior when the file does not exist."""
+    mocker.patch("builtins.open", side_effect=FileNotFoundError("No such file"))
+
+    with pytest.raises(FileNotFoundError):
+        _read_json_file("non/existent/path.json")
+
+
+def test_invalid_json(mocker):
+    """Tests reading a file with malformed JSON."""
+    mock_content = '{"key": "value",}'
+    mocker.patch("builtins.open", mocker.mock_open(read_data=mock_content))
+
+    with pytest.raises(json.JSONDecodeError):
+        _read_json_file("fake/path.json")

.github/workflows/generator.yml

@@ -21,10 +21,11 @@ jobs:
     - name: Setup Python
       uses: actions/setup-python@v5
       with:
-        python-version: "3.10"
-    - name: Install pytest
+        python-version: "3.11"
+    - name: Install dependencies
       run: |
-        python -m pip install pytest
+        python -m pip install --upgrade pip
+        pip install -r .generator/requirements-test.in
     - name: Run generator_cli tests
       run: |
         pytest .generator/test_cli.py

cloudbuild.yaml

@@ -0,0 +1,28 @@
+# Copyright 2025 Google LLC
+#
+# 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.
+
+steps:
+  # This step builds the Docker image.
+  - name: 'gcr.io/cloud-builders/docker'
+    args:
+      - 'build'
+      - '-t'
+      - 'gcr.io/$PROJECT_ID/python-librarian-generator:latest'
+      - '-f'
+      - '.generator/Dockerfile'
+      - '.'
+
+# This section automatically create a storage bucket for storing docker build logs.
+options:
+  default_logs_bucket_behavior: REGIONAL_USER_OWNED_BUCKET