title: Python Custom Activity for Azure-Data Factory
body: <p>I am trying to create a Data Factory that once a week copies and process large blob files (The Source) to a SQL database (The Sink) in python - by reading the input data set line by line, extracting an ID - using that ID to do a lookup on CosmosDB to get an additional piece of data recomposing the output dataset and writing to the sink. 
  I have a python script that does this once off (ie reads the entire blob every time) without ADF but am now wanting use the scheduling features on ADF to automate this.</p>
  
  <p>Is there a way of creating a custom copy activity in Python that I can inject my current code logic into. Azure currently only documents .Net custom activities (<a href="https://docs.microsoft.com/en-us/azure/data-factory/transform-data-using-dotnet-custom-activity" rel="nofollow noreferrer">https://docs.microsoft.com/en-us/azure/data-factory/transform-data-using-dotnet-custom-activity</a>) which does not fit into my stack.</p>
  
  <p>The python azure SDK doesn't currently have any documentation on creating custom activity.</p>