How do I connect Amazon RDS - Microsoft SQL Server through Glue Spark type jobs using python ?

You have several options:

• You can use the from_options reader, specifying the connection details or using a connection where you store the connection properties and credentials https://docs.aws.amazon.com/glue/latest/dg/aws-glue-api-crawler-pyspark-extensions-dynamic-frame-reader.html#aws-glue-api-crawler-pyspark-extensions-dynamic-frame-reader-from_options
• You could create catalog tables that represent the SQLServer tables, using a connection and crawler and then read from the table using from_catalog API.
• You can read using the Spark API spark.jdbc()