added a simple pub/sub topic for testing (#27610)

* added a simple pub/sub topic for testing

* update the code based on comments

---------

Co-authored-by: xqhu <xqhu@google.com>

Author: liferoad

.test-infra/pubsub/README.md

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+<!--
+    Licensed to the Apache Software Foundation (ASF) under one
+    or more contributor license agreements.  See the NOTICE file
+    distributed with this work for additional information
+    regarding copyright ownership.  The ASF licenses this file
+    to you 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.
+-->
+
+# Overview
+
+This folder contains Python scripts to create a Pub/Sub topic under
+the GCP project `apache-beam-testing` and test the topic.
+The created topic is `projects/apache-beam-testing/topics/Imagenet_openimage_50k_benchmark`.
+
+# Create the topic `Imagenet_openimage_50k_benchmark`
+
+- Create one VM to run `gcs_image_looper.py`.
+  The VM `pubsub-test-do-not-delete` was already created under `apache-beam-testing`.
+  Keep the script running to continuously publish data.
+- You might run `gcloud auth application-default login` to get the auth.
+- You might run `pip install google-cloud-core google-cloud-pubsub google-cloud-storage`.
+- Must make `Imagenet_openimage_50k_benchmark` public by adding `allAuthenticatedUsers` to the Pub/Sub Subscriber role.
+
+# Tes the topic by subscribing it
+
+- Run `test_image_looper.py` to check whether you could get any data.

.test-infra/pubsub/gcs_image_looper.py

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+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You 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.
+#
+"""This executable loops image filepaths from a gcs bucket file."""
+import random
+import time
+
+from google.api_core.exceptions import AlreadyExists
+from google.cloud import pubsub_v1
+from google.cloud import storage
+
+# use the eou project and gcs to run the word looper
+project_id = "apache-beam-testing"
+gcs_bucket = "apache-beam-ml"
+num_images_per_second = 5
+
+publisher = pubsub_v1.PublisherClient()
+image_file_path = "testing/inputs/openimage_50k_benchmark.txt"
+topic_name = "Imagenet_openimage_50k_benchmark"
+topic_path = publisher.topic_path(project_id, topic_name)
+
+
+class ImageLooper(object):
+    """Loop the images in a gcs bucket file and publish them to a pubsub topic.
+  """
+    content = ""
+    cursor = 0
+
+    def __init__(self, filename):
+        self._read_gcs_file(filename)
+
+    def get_next_image(self):
+        """Returns the next image randomly."""
+        next_image = ""
+        while not next_image:
+            image_id = random.randint(0, len(self.content) - 1)
+            next_image = self.content[image_id]
+        return next_image
+
+    def _read_gcs_file(self, filename):
+        client = storage.Client()
+        bucket = client.get_bucket(gcs_bucket)
+        blob = bucket.get_blob(filename)
+        self.content = blob.download_as_string().decode("utf-8").split('\n')
+
+
+try:
+    publisher.create_topic(request={"name": topic_path})
+except AlreadyExists:
+    pass
+
+looper = ImageLooper(image_file_path)
+while True:
+    image = looper.get_next_image()
+    publisher.publish(topic_path, data=image.encode("utf-8"))
+    time.sleep(1 / num_images_per_second)

.test-infra/pubsub/test_image_looper.py

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+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You 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.
+#
+"""This executable test the pub/sub topic created by gcs_image_looper.py"""
+
+from concurrent.futures import TimeoutError
+
+from google.cloud import pubsub_v1
+from google.api_core.exceptions import AlreadyExists
+
+project_id = "apache-beam-testing"
+subscription_id = "test-image-looper"
+topic_id = "Imagenet_openimage_50k_benchmark"
+
+publisher = pubsub_v1.PublisherClient()
+subscriber = pubsub_v1.SubscriberClient()
+topic_path = publisher.topic_path(project_id, topic_id)
+subscription_path = subscriber.subscription_path(project_id, subscription_id)
+
+try:
+    subscription = subscriber.create_subscription(request={
+        "name": subscription_path,
+        "topic": topic_path
+    })
+    print(f"Subscription created: {subscription}")
+except AlreadyExists:
+    subscriber.delete_subscription(request={"subscription": subscription_path})
+    subscription = subscriber.create_subscription(request={
+        "name": subscription_path,
+        "topic": topic_path
+    })
+    print(f"Subscription recreated: {subscription}")
+
+timeout = 3.0
+
+total_images = []
+
+
+def callback(message: pubsub_v1.subscriber.message.Message) -> None:
+    total_images.append(message.data.decode())
+    message.ack()
+
+
+streaming_pull_future = subscriber.subscribe(subscription_path,
+                                             callback=callback)
+print(f"Listening for messages on {subscription_path}..\n")
+
+try:
+    # When `timeout` is not set, result() will block indefinitely,
+    # unless an exception is encountered first.
+    streaming_pull_future.result(timeout=timeout)
+except TimeoutError:
+    streaming_pull_future.cancel()  # Trigger the shutdown.
+    streaming_pull_future.result()  # Block until the shutdown is complete.
+print("Results: \n", total_images)
+
+subscriber.delete_subscription(request={"subscription": subscription_path})
+
+print(f"Subscription deleted: {subscription_path}.")