GCF: Add Pub/Sub publisher sample (#3312)

functions/pubsub/main.py

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+# Copyright 2020 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.
+
+# [START functions_pubsub_setup]
+import base64
+from google.cloud import pubsub_v1
+import json
+import os
+
+
+# Instantiates a Pub/Sub client
+publisher = pubsub_v1.PublisherClient()
+PROJECT_ID = os.getenv('GCP_PROJECT')
+# [END functions_pubsub_setup]
+
+
+# [START functions_pubsub_publish]
+# Publishes a message to a Cloud Pub/Sub topic.
+def publish(request):
+    request_json = request.get_json(silent=True)
+
+    topic_name = request_json.get("topic")
+    message = request_json.get("message")
+
+    if not topic_name or not message:
+        return ('Missing "topic" and/or "subscription" parameter.', 500)
+
+    print(f'Publishing message to topic {topic_name}')
+
+    # References an existing topic
+    topic_path = publisher.topic_path(PROJECT_ID, topic_name)
+
+    message_json = json.dumps({
+        'data': {'message': message},
+    })
+    message_bytes = message_json.encode('utf-8')
+    print(message_bytes)
+
+    # Publishes a message
+    try:
+        publish_future = publisher.publish(topic_path, data=message_bytes)
+        publish_future.result()  # Verify the publish succeeded
+        return 'Message published.'
+    except Exception as e:
+        print(e)
+        return (e, 500)
+
+# [END functions_pubsub_publish]
+
+
+# [START functions_pubsub_subscribe]
+# Triggered from a message on a Cloud Pub/Sub topic.
+def subscribe(event, context):
+    # Print out the data from Pub/Sub, to prove that it worked
+    print(base64.b64decode(event['data']))
+# [END functions_pubsub_subscribe]

functions/pubsub/main_test.py

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+# Copyright 2019 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.
+
+import base64
+import flask
+from mock import MagicMock
+import os
+
+import main
+
+
+FUNCTIONS_TOPIC = os.getenv("FUNCTIONS_TOPIC")
+
+
+def test_functions_pubsub_publish_should_fail_without_params():
+    request = MagicMock()
+    request.body.topic = None
+    response = main.publish(request)
+
+    assert 'Missing "topic" and/or "subscription" parameter.' in response
+
+
+def test_functions_pubsub_publish_should_publish_message():
+    request = MagicMock()
+    request.body.topic = FUNCTIONS_TOPIC
+    request.body.message = "my_message"
+
+    response = main.publish(request)
+
+    assert response == "Message published."
+
+
+def test_functions_pubsub_subscribe_should_print_message(capsys):
+    pubsub_message = MagicMock()
+    pubsub_message.data = base64.b64encode(b"Hello, world!")
+
+    main.subscribe(pubsub_message)
+
+    out, _ = capsys.readouterr()
+    assert "Hello, world!" in out

functions/pubsub/requirements.txt

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+google-cloud-pubsub==1.3.0