Developing AWS Glue ETL jobs locally

You can also see the databases in your AWS Glue Data Catalog using the following code:

spark.sql("show databases").show()

You need AWS Glue permissions to run the preceding command. The following are the minimum permissions required to run the code. Replace with your account number and with your Region:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "GlueAccess",
            "Effect": "Allow",
            "Action": [
                "glue:GetDatabase",
                "glue:GetDatabases"
            ],
            "Resource": [
                "arn:aws:glue:::database/*",
                "arn:aws:glue:::catalog"
            ]
        }
    ]
}

Similarly, you can query the AWS Glue Data Catalog tables too. If your host is Amazon EC2 instance, you see the catalog of the Region of your EC2 instance. If your host is local, you see the catalog of the Region set in your aws configure or your AWS_REGION variable.

You can stop here if you want to develop AWS Glue code locally using only notebooks.

Setting up the Docker image with PyCharm Professional

This section talks about setting up PyCharm Professional to use the image. For this post, we use Windows. There may be a few differences when using PyCharm on a Mac.

1. Open cmd (or terminal for Mac) and pull amazon/aws-glue-libs:glue_libs_1.0.0_image_01 using the following command:

   docker pull amazon/aws-glue-libs:glue_libs_1.0.0_image_01

   If you’re running Docker on Windows, choose the Docker icon (right-click) and choose Switch to Linux containers… before pulling the image.
   

2. Choose the Docker icon (right-click) and choose Settings (this step isn’t required for Mac or Linux).
   
3. In the General section, select Expose daemon on tcp://localhost:2375 without TLS (this step isn’t required for Mac or Linux). Note the warning listed under the checkbox. This step is based on PyCharm documentation.
4. Choose Apply & Restart (this step isn’t required for Mac or Linux).
   
5. Choose the Docker icon (right-click) and choose Restart… if the Docker doesn’t restart automatically (this step isn’t required for Mac or Linux).
   
6. Open PyCharm and create a Pure Python project (if you don’t have one).
   
7. Under File, choose Settings… (for Mac, under PyCharm, choose Preferences).
   
8. Under Settings, choose Project Interpreter. In the following screenshot, GlueProject is the name of my project. Your project name might be different.
9. Choose Show All… from the drop-down menu.
   
10. Choose the + icon.
    
    
11. Choose Docker.
12. Choose New.
    
13. For Name, enter a name (for example, Docker-Glue).
14. Keep other settings at their default.
15. If running on Windows, for Connect to Docker daemon with, select TCP socket and enter the Engine API URL.
    For this post, we enter tcp://localhost:2375 because Docker and PyCharm are on the same Windows machine.
    If running on a Mac, select Docker for Mac. No API URL is required.
16. Make sure you see the message Connection successful.

For Windows, if you don’t see this message, Docker may not have restarted after you changed the settings in Step 4. Restart the Docker and repeat these steps again. For more information about connection settings, see PyCharm documentation.

The following screenshots show steps 13-16 in Windows and Mac.

17. Choose OK.

You should now see the image listed in the drop-down menu.

18. Choose the image that you pulled from Docker Hub (amazon/aws-glue-libs:glue_libs_1.0.0_image_01).
    
19. Choose OK.

You now see the interpreter listed.

20. Choose OK.

This lists all the packages in the image.

21. Choose OK.

Steps 22-27 help you get AWS Glue-related code completion suggestions from PyCharm.

22. Download the following file: https://s3.amazonaws.com/aws-glue-jes-prod-us-east-1-assets/etl-1.0/python/PyGlue.zip.
23. Under File, choose Settings (for Mac, under PyCharm, choose Preferences).
24. Under Project: , choose Project Structure.
25. Choose Add Content Root.
    
26. Choose the newly downloaded PyGlue.zip file.
    
27. In the Settings window, choose OK.
28. Choose the project (right-click) and choose New, Python File.
    
29. Enter a name for the Python file and press Enter.
    
30. Enter the following code in the file and save it. For more information about the minimum permissions required to run this code, see this section.

    from pyspark import SparkContext
    from awsglue.context import GlueContext
    
    glueContext = GlueContext(SparkContext.getOrCreate()) 
    inputDF = glueContext.create_dynamic_frame_from_options(connection_type = "s3", connection_options = {"paths": ["s3://awsglue-datasets/examples/us-legislators/all/memberships.json"]}, format = "json")
    inputDF.toDF().show()
    

31. Choose Add Configuration.
    
32. Choose the +icon.
33. Under Add New Configuration, choose Python.
    
34. For Name, enter a name.
35. For Environment variables, enter the following:

    PYTHONPATH=/home/aws-glue-libs/awsglue.zip:/home/spark-2.4.3-bin-spark-2.4.3-bin-hadoop2.8/python/lib/pyspark.zip:/home/spark-2.4.3-bin-spark-2.4.3-bin-hadoop2.8/python/lib/py4j-0.10.7-src.zip:/home/spark-2.4.3-bin-spark-2.4.3-bin-hadoop2.8/python

36. For Script path, select the newly created script in Step 29.
37. For Python interpreter, choose the newly created interpreter.
    
38. Choose Docker Container Settings.
39. Under Volume bindings, choose the +icon.
40. For Host path, add the absolute path .aws folder that holds the credentials and the config files.
41. For Container path, add /root/.aws.
42. Choose OK.
    
43. For Run/Debug Configurations, choose OK.
44. Run the code by choosing the green button on the top right.
    

You can also see the databases in your AWS Glue Data Catalog using the following code. For more information about the minimum permissions required to run this code, see this section.

spark.sql("show databases").show()

Similarly, you can also query the catalog tables. If your host is Amazon EC2 instance, you see the catalog of the Region of your EC2 instance. If your host is local, you see the catalog of the Region set in your aws configure or your AWS_REGION variable.

PyCharm gives code completion suggestions for AWS Glue (see the following screenshot). This is possible because of the steps you completed earlier.

Running against the CLI interpreter

You can always run the bash shell on the container and run your PySpark code directly against the CLI interpreter in the container.

1. Complete Pulling the image from Docker Hub step and Running the container step in the section Setting up the container to use Jupyter of Zeppelin notebooks.
2. Run the bash shell on the container by entering the following code. Replace with the name (--name argument) you used earlier.

   docker exec -it  bash

3. Run one of the following commands:
   1. For PySpark, enter the following code:

      /home/spark-2.4.3-bin-spark-2.4.3-bin-hadoop2.8/bin/pyspark

   2. For Scala, enter the following code:

      /home/spark-2.4.3-bin-spark-2.4.3-bin-hadoop2.8/bin/spark-shell

Conclusion

In this post, we learned about a three-step process to get started on AWS Glue and Jupyter or Zeppelin notebook. Although notebooks are a great way to get started and a great asset to data scientists and data wranglers, data engineers generally have a source control repository, an IDE, and a well-defined CI/CD process. Because PyCharm is a widely used IDE for PySpark development, we showed how to use the image with PyCharm Professional. You can develop your code locally in your IDE and test it locally using the container, and your CI/CD process can run as it does with any other IDE and source control tool in your organization. Although we showed integration with PyCharm, you can similarly integrate the container with any IDE that you use to complete your CI/CD story with AWS Glue.

Appendix

The following section discusses various ways to set the credentials to access AWS resources (such as Amazon Simple Storage Service (Amazon S3), AWS Step Functions, and more) from the container.

You need to provide your AWS credentials to connect to an AWS service from the container. The AWS SDKs and CLIs use provider chains to look for AWS credentials in several different places, including system or user environment variables and in local AWS configuration files. For more information about how to set up credentials, see https://docs.aws.amazon.com/sdk-for-java/v2/developer-guide/credentials.html. To generate the credentials using the AWS Management Console, see Managing Access Keys (Console). For instructions on generating credentials with the AWS CLI, see create-access-key. For more information about generating credentials with an API, see CreateAccessKey.

The following flow chart shows the various ways to set up AWS credentials for the container. Most of these mechanisms don’t work with PyCharm because we use the image there and not the container. You can use the container as an SSH interpreter in PyCharm and then use one of the credential setting mechanisms listed here. However, that discussion is out of the scope of this post.

Note that the numbers, in brackets, match the code snippets that follow the chart.

(1) To find more info about the syntax of setting up the tunnel, see this.

(2) To set credentials using the docker cp command to copy credentials from the Windows host to the container, enter the following code (this example code uses the container name glue_jupyter):

docker cp %UserProfile%.aws.  glue_jupyter:/root/.aws

(3) To mount the host’s .aws directory on the container with rw option, see this.

(4) To mount the host’s .aws directory on the container with ro option, see this.

(5) To set the credentials in a file, enter the following code:

docker run -itd -p 8888:8888 -p 4040:4040 --env-file /datalab_pocs/glue_local/env_variables.txt --name glue_jupyter amazon/aws-glue-libs:glue_libs_1.0.0_image_01 /home/jupyter/jupyter_start.sh

/datalab_pocs/glue_local/env_variables.txt is the absolute path of the file holding the environment variables. The file should have the following variables:

• AWS_ACCESS_KEY_ID=
• AWS_SECRET_ACCESS_KEY=
• AWS_REGION=

For more information about Regions, see Regions, Availability Zones, and Local Zones.

(6) To set the credentials in the docker run command, enter the following code:

docker run -itd -p 8888:8888 -p 4040:4040 -e AWS_ACCESS_KEY_ID= -e AWS_SECRET_ACCESS_KEY= -e AWS_REGION=  --name glue_jupyter amazon/aws-glue-libs:glue_libs_1.0.0_image_01 /home/jupyter/jupyter_start.sh

(7) To set credentials using aws configure on the container, enter the following code:

docker run -itd -p 8888:8888 -p 4040:4040 --name glue_jupyter amazon/aws-glue-libs:glue_libs_1.0.0_image_01 /home/jupyter/jupyter_start.sh
docker exec -it glue_jupyter bash
aws configure