title: Is there a Google Dataflow MongoDB Source/Sink?
body: <p>I know Google Dataflow only officially supports as I/O for a Dataflow a file in Google Cloud Storage, BigQuery, Avro files or Pub/Sub out of the box.</p>
  
  <p>But as it has an <a href="https://cloud.google.com/dataflow/model/custom-io" rel="nofollow">API for Custom Source and Sink</a> I was wondering, is there some Pipeline I/O implementation for MongoDB?</p>
  
  <p>Right now I will have to either migrate my data to BigQuery or write the whole Pipeline I/O implementation before even being able to know if Google Dataflow is a viable solution to my current problems.</p>
  
  <p>I tried googling and looking at the <a href="https://github.com/GoogleCloudPlatform/DataflowJavaSDK/issues?q=is%3Aissue%20mongodb" rel="nofollow">current SDK issues</a> and didn't see anything related. I even started to wonder if I missed something very basic from Google Dataflow concept and docs that completely invalidades this initial idea to use MongoDB as a data source.</p>