Document recommendations for retrying blob.upload_from_filename

[tschaub]

I'm seeing frequent 503 and 504 responses using the blob.upload_from_filename() method. An example trace looks like this:

503 POST https://storage.googleapis.com/upload/storage/v1/b/my-bucket/o?uploadType=multipart: {
  "error": {
    "code": 503,
    "message": "Backend Error",
    "errors": [
      {
        "message": "Backend Error",
        "domain": "global",
        "reason": "backendError"
      }
    ]
  }
}
: (u'Request failed with status code', 503, u'Expected one of', 200)' - Calling rollback() ...
Traceback (most recent call last):
  File "/my/app/module.py", line 112, in upload
    blob.upload_from_filename(file_path)
  File "/usr/local/lib/python2.7/dist-packages/google/cloud/storage/blob.py", line 2471, in upload_from_filename
    checksum=checksum,
  File "/usr/local/lib/python2.7/dist-packages/google/cloud/storage/blob.py", line 2359, in upload_from_file
    _raise_from_invalid_response(exc)
  File "/usr/local/lib/python2.7/dist-packages/google/cloud/storage/blob.py", line 3886, in _raise_from_invalid_response
    raise exceptions.from_http_status(response.status_code, message, response=response)
ServiceUnavailable: 503 POST https://storage.googleapis.com/upload/storage/v1/b/my-bucket/o?uploadType=multipart: {
  "error": {
    "code": 503,
    "message": "Backend Error",
    "errors": [
      {
        "message": "Backend Error",
        "domain": "global",
        "reason": "backendError"
      }
    ]
  }
}
: (u'Request failed with status code', 503, u'Expected one of', 200)

It looks like this method calls blob.upload_from_file() with num_retries=None, so there is no retry strategy applied. I also see that the num_retries argument is documented as deprecated.

Does this library provide an alternative way to retry blob.upload_from_filename() or blob.upload_from_file()? I can wrap these calls in retry logic of my own, but I see that retries are enabled by default for other functions.

I'm using google-cloud-storage==1.34.0. I've already pulled in google-resumable-media==1.20.0 so I should be getting the recent resumable media retry fixes that came with #342.

Thanks for any tips on retrying uploads.

[HemangChothani]

@tschaub See the documentation of num_retries here

By default, only uploads with if_metageneration_match set will be retried for the transient errors.For now num_retires parameter working fine and it will remove in the future so you can use that.
The num_retries is not exposed for blob.upload_from_filename method so for now you can use blob.upload_from_file method.

google-resumable-media==1.2.0 automatically pulled when you update your storage library to google-cloud-storage==1.35.0 and you will get the recent resumable media retry fix with it.