title: pyWriteDynamicFrame: Unrecognized scheme null; expected s3, s3n, or s3a [Glue to Redshift]
body: <p>While executing a Glue Job, after the necessaries transformations I am writing the results of my Spark <code>df</code> to a Redshift table like this:</p>
  
  <pre><code>dynamic_df = DynamicFrame.fromDF(df, glue_context, "dynamic_df")
  
  glue_context.write_dynamic_frame.from_jdbc_conf(
      frame=dynamic_df, catalog_connection=args['catalog_connection'],
      connection_options={"dbtable": args['dbschema'] + "." + args['dbtable'], "database": args['database']},
      transformation_ctx="write_my_df")
  </code></pre>
  
  <p>But I am receiving this exception:</p>
  
  <pre><code>19/08/23 14:29:31 ERROR __main__: Traceback (most recent call last):
  File "/mnt/yarn/usercache/root/appcache/application_1572375324962_0001/container_1572375324962_0001_01_000001/pyspark.zip/pyspark/sql/utils.py", line 63, in deco
  return f(*a, **kw)
  File "/mnt/yarn/usercache/root/appcache/application_1572375324962_0001/container_1572375324962_0001_01_000001/py4j-0.10.7-src.zip/py4j/protocol.py", line 328, in get_return_value
  format(target_id, ".", name), value)
  py4j.protocol.Py4JJavaError: An error occurred while calling o190.pyWriteDynamicFrame.
  : java.lang.IllegalArgumentException: Unrecognized scheme null; expected s3, s3n, or s3a
  </code></pre>
  
  <p>What am I doing wrong? How can I solve it?</p>