[jira] [Created] (BEAM-1788) Using google-cloud-datastore in Beam requires re-authentication

["Mike Lambert (JIRA)" <ji...@apache.org>]

Mike Lambert created BEAM-1788:
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             Summary: Using google-cloud-datastore in Beam requires re-authentication
                 Key: BEAM-1788
                 URL: https://issues.apache.org/jira/browse/BEAM-1788
             Project: Beam
          Issue Type: Improvement
          Components: beam-model-runner-api
            Reporter: Mike Lambert
            Assignee: Kenneth Knowles
            Priority: Minor


When I run a pipeline, I believe everything (params, lexically scoped variables) must be pickleable for the individual processing stages.

I have to load a dependent datastore record in one of my processing pipelines. (Horribly inefficient, I know, but it's my DB design for now...)

A {{google.cloud.datastore.Client()}} is not serializable due to the {{google.cloud.datastore._http.Connection}} it contains, that is using GRPC:

{{
  File "lib/apache_beam/transforms/ptransform.py", line 474, in __init__
    self.args = pickler.loads(pickler.dumps(self.args))
  File "lib/apache_beam/internal/pickler.py", line 212, in loads
    return dill.loads(s)
  File "/Users/me/Library/Python/2.7/lib/python/site-packages/dill/dill.py", line 277, in loads
    return load(file)
  File "/Users/me/Library/Python/2.7/lib/python/site-packages/dill/dill.py", line 266, in load
    obj = pik.load()
  File "/usr/local/Cellar/python/2.7.12_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/pickle.py", line 864, in load
    dispatch[key](self)
  File "/usr/local/Cellar/python/2.7.12_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/pickle.py", line 1089, in load_newobj
    obj = cls.__new__(cls, *args)
  File "src/python/grpcio/grpc/_cython/_cygrpc/channel.pyx.pxi", line 35, in grpc._cython.cygrpc.Channel.__cinit__ (src/python/grpcio/grpc/_cython/cygrpc.c:4022)
TypeError: __cinit__() takes at least 2 positional arguments (0 given)
}}

So instead, constructing a Client inside my pipeline...it appears to be jumping through hoops to recreate the Client, in that *each* execution of my pipeline is printing:
{{ DEBUG:google_auth_httplib2:Making request: POST https://accounts.google.com/o/oauth2/token }}

I'm sure Google SRE would be very unhappy if I scaled up this mapreduce. :)

This is a tricky cross-team interaction issue (only occurs for those using google-cloud-datastore *and* apache-beam google-dataflow), so not sure the proper place to file this. I've cross-posted it at https://github.com/GoogleCloudPlatform/google-cloud-python/issues/3191



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