azure synapse analytics /Apache spark logging

We are looking to implement logging using log4j in Azure synapse analytics - Spark pool / pyspark

could not find any documentation for application level logging in azure synapse analytics. 

is there any default log library supported in azure synapse analytics ( log4j or any other) 

We are not able to upload the log4j.properties files into Synapse workspace as the workspace only accepts the .txt files for configuration. 

We were able to capture the spark logs using below MSFT docs.  azure-docs/azure-synapse-diagnostic-emitters-azure-storage.md at master · MicrosoftDocs/azure-docs · GitHub 

now want to capture only Application logs with some logger library. 

There are good articles for log4j implementation for  Azure Databricks. but we are not able follow same steps as the spark cluster in synapse not allowing to go into ubuntu folder of the cluster.  

any documentation or samples for synapse analytics will be a great help. 

Mark Kromer  , James Serra  - adding you for visibility