# Custom Python versions on EMR Serverless

Occasionally, you'll require a specific Python version. While EMR Serverless uses Python 3.7.10 by default, you can upgrade by building your own virtual environment with the desired version and copying the binaries when you package your virtual environment.

Let's say you want to make use of the new `match` statements in Python 3.10 - We'll use a Dockerfile to install Python 3.10.6 and create our custom virtual environment.

Once created, we'll upload the new virtual environment and a sample Python script only compatible with 3.10 to S3.

```
# Define a variable for code storage and job logs
S3_BUCKET=<YOUR_S3_BUCKET>

# Build our custom venv with BuildKit backend
DOCKER_BUILDKIT=1 docker build --output . .

# Upload the artifacts to S3
aws s3 cp pyspark_3.10.6.tar.gz     s3://${S3_BUCKET}/artifacts/pyspark/
aws s3 cp python_3.10.py            s3://${S3_BUCKET}/code/pyspark/
```

We'll then submit our job with the venv archive provided in `spark.archives` and configure our Python environment variables appropriately.

```
aws emr-serverless start-job-run \
    --name custom-python \
    --application-id $APPLICATION_ID \
    --execution-role-arn $JOB_ROLE_ARN \
    --job-driver '{
        "sparkSubmit": {
            "entryPoint": "s3://'${S3_BUCKET}'/code/pyspark/python_3.10.py",
            "sparkSubmitParameters": "--conf spark.archives=s3://'${S3_BUCKET}'/artifacts/pyspark/pyspark_3.10.6.tar.gz#environment --conf spark.emr-serverless.driverEnv.PYSPARK_DRIVER_PYTHON=./environment/bin/python --conf spark.emr-serverless.driverEnv.PYSPARK_PYTHON=./environment/bin/python --conf spark.emr-serverless.executorEnv.PYSPARK_PYTHON=./environment/bin/python"
        }
    }' \
    --configuration-overrides '{
        "monitoringConfiguration": {
            "s3MonitoringConfiguration": {
                "logUri": "s3://'${S3_BUCKET}'/logs/"
            }
        }
    }'
```

If we copy the output of the job, we should see the new Python version works as expected.

```
 aws s3 cp s3://${S3_BUCKET}/logs/applications/${APPLICATION_ID}/jobs/${JOB_RUN_ID}/SPARK_DRIVER/stdout.gz - | gunzip
```

```
/home/hadoop/environment/bin/python
3.10.6 (main, Aug 12 2022, 18:37:31) [GCC 7.3.1 20180712 (Red Hat 7.3.1-15)]
Damon
```