ImageMagick: use separate bucket for blurred images. (#2199)

* ImageMagick: use separate bucket for blurred images.

* Address Charlie's comments

* Fix lint

functions/imagemagick/README.md

@@ -21,15 +21,23 @@ Functions for your project.
 
 1. Create a Cloud Storage Bucket:
 
-        gsutil mb gs://YOUR_BUCKET_NAME
+        gsutil mb gs://YOUR_INPUT_BUCKET_NAME
 
     This storage bucket is used to upload images for the function to check.
 
+1. Create a second Cloud Storage Bucket:
+
+         gsutil mb gs://YOUR_OUTPUT_BUCKET_NAME
+
+     This second storage bucket is used to store blurred images. (Un-blurred images will not be saved to this bucket.)
+
+     This is necessary because saving the blurred image to the input bucket would cause your function to be invoked a second time with the blurred image itself.
+
 1. Deploy the `blur_offensive_images` function with a Storage trigger:
 
-        gcloud functions deploy blur_offensive_images --trigger-bucket=YOUR_BUCKET_NAME --runtime python37
+        gcloud functions deploy blur_offensive_images --trigger-bucket=YOUR_INPUT_BUCKET_NAME --set-env-vars BLURRED_BUCKET_NAME=YOUR_OUTPUT_BUCKET_NAME --runtime python37
 
-    * Replace `YOUR_BUCKET_NAME` with the name of the Cloud Storage Bucket you created earlier.
+    * Replace `YOUR_INPUT_BUCKET_NAME` and `YOUR_OUTPUT_BUCKET_NAME` with the names of the respective Cloud Storage Buckets you created earlier.
 
 1.  Upload an offensive image to the Storage bucket, such as this image of
     a flesh-eating zombie: https://cdn.pixabay.com/photo/2015/09/21/14/24/zombie-949916_1280.jpg

functions/imagemagick/main.py

@@ -73,12 +73,14 @@ def __blur_image(current_blob):
 
     print(f'Image {file_name} was blurred.')
 
-    # Send Blurred image back to the bucket (with a 'blurred-' prefix).
-    # The prefix is necessary to avoid re-invoking the function upon upload.
-    new_file_name = f'blurred-{file_name}'
-    new_blob = current_blob.bucket.blob(new_file_name)
+    # Upload result to a second bucket, to avoid re-triggering the function.
+    # You could instead re-upload it to the same bucket + tell your function
+    # to ignore files marked as blurred (e.g. those with a "blurred" prefix)
+    blur_bucket_name = os.getenv('BLURRED_BUCKET_NAME')
+    blur_bucket = storage_client.bucket(blur_bucket_name)
+    new_blob = blur_bucket.blob(file_name)
     new_blob.upload_from_filename(temp_local_filename)
-    print(f'Blurred image was uploaded to {new_file_name}.')
+    print(f'Blurred image uploaded to: gs://{blur_bucket_name}/{file_name}')
 
     # Delete the temporary file.
     os.remove(temp_local_filename)

functions/imagemagick/main_test.py

@@ -79,20 +79,23 @@ def test_process_safe_image(
 
 @patch('main.os')
 @patch('main.Image')
-def test_blur_image(image_mock, os_mock, capsys):
+@patch('main.storage_client')
+def test_blur_image(storage_client, image_mock, os_mock, capsys):
     filename = str(uuid.uuid4())
+    blur_bucket = 'blurred-bucket-' + str(uuid.uuid4())
 
     os_mock.remove = MagicMock()
     os_mock.path = MagicMock()
     os_mock.path.basename = MagicMock(side_effect=(lambda x: x))
 
+    os_mock.getenv = MagicMock(return_value=blur_bucket)
+
     image_mock.return_value = image_mock
     image_mock.__enter__.return_value = image_mock
 
     blob = UserDict()
     blob.name = filename
     blob.bucket = UserDict()
-    blob.bucket.blob = MagicMock(return_value=blob)
     blob.download_to_filename = MagicMock()
     blob.upload_from_filename = MagicMock()
 
@@ -102,6 +105,6 @@ def test_blur_image(image_mock, os_mock, capsys):
 
     assert f'Image {filename} was downloaded to' in out
     assert f'Image {filename} was blurred.' in out
-    assert f'Blurred image was uploaded to blurred-{filename}.' in out
+    assert f'Blurred image uploaded to: gs://{blur_bucket}/{filename}' in out
     assert os_mock.remove.called
     assert image_mock.resize.called

functions/imagemagick/requirements-dev.txt

@@ -0,0 +1,4 @@
+mock==3.0.5
+six==1.12.0
+uuid==1.30
+pytest==4.6.2