Tutorial: Use a REPL shell with your development endpoint - Amazon Glue
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Tutorial: Use a REPL shell with your development endpoint

In Amazon Glue, you can create a development endpoint and then invoke a REPL (Read–Evaluate–Print Loop) shell to run PySpark code incrementally so that you can interactively debug your ETL scripts before deploying them.

In order to use a REPL on a development endpoint, you need to have authorization to SSH to the endpoint.

  1. On your local computer, open a terminal window that can run SSH commands, and paste in the edited SSH command. Run the command.

    Assuming that you accepted Amazon Glue version 1.0 with Python 3 for the development endpoint, the output will look like this:

    Python 3.6.8 (default, Aug  2 2019, 17:42:44)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux
Type "help", "copyright", "credits" or "license" for more information.
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/usr/share/aws/glue/etl/jars/glue-assembly.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/usr/lib/spark/jars/slf4j-log4j12-1.7.16.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory]
Setting default log level to "WARN".
To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel).
2019-09-23 22:12:23,071 WARN  [Thread-5] yarn.Client (Logging.scala:logWarning(66)) - Neither spark.yarn.jars nor spark.yarn.archive is set, falling back to uploading libraries under SPARK_HOME.
2019-09-23 22:12:26,562 WARN  [Thread-5] yarn.Client (Logging.scala:logWarning(66)) - Same name resource file:/usr/lib/spark/python/lib/pyspark.zip added multiple times to distributed cache
2019-09-23 22:12:26,580 WARN  [Thread-5] yarn.Client (Logging.scala:logWarning(66)) - Same path resource file:///usr/share/aws/glue/etl/python/PyGlue.zip added multiple times to distributed cache.
2019-09-23 22:12:26,581 WARN  [Thread-5] yarn.Client (Logging.scala:logWarning(66)) - Same path resource file:///usr/lib/spark/python/lib/py4j-src.zip added multiple times to distributed cache.
2019-09-23 22:12:26,581 WARN  [Thread-5] yarn.Client (Logging.scala:logWarning(66)) - Same path resource file:///usr/share/aws/glue/libs/pyspark.zip added multiple times to distributed cache.
Welcome to
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   /__ / .__/\_,_/_/ /_/\_\   version 2.4.3
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Using Python version 3.6.8 (default, Aug  2 2019 17:42:44)
SparkSession available as 'spark'.
>>>

  2. Test that the REPL shell is working correctly by typing the statement, print(spark.version). As long as that displays the Spark version, your REPL is now ready to use.

  3. Now you can try executing the following simple script, line by line, in the shell:

    import sys
from pyspark.context import SparkContext
from awsglue.context import GlueContext
from awsglue.transforms import *
glueContext = GlueContext(SparkContext.getOrCreate())
persons_DyF = glueContext.create_dynamic_frame.from_catalog(database="legislators", table_name="persons_json")
print ("Count:  ", persons_DyF.count())
persons_DyF.printSchema()