Glue streaming job throws FileDownloadException from S3 location

This error indicates that your AWS Glue streaming job encountered an issue downloading a Parquet file from Amazon S3 during batch processing. Based on the error message, there are several potential causes for this FileDownloadException:

1. Temporary S3 Access Issues: Even though the file exists and is normally accessible, there might have been temporary permission issues or S3 service disruptions at the time of the job execution.

2. IAM Role Permissions: The IAM role used by your Glue job might have insufficient permissions to access the specific S3 bucket or objects. This could be due to:

• Bucket policies restricting access
• IAM policies that need updating
• S3 ACL settings
• S3 Block Public Access settings
• S3 object lock settings
• VPC endpoint policies
• AWS organization policies
• Access point settings

3. Network Connectivity Issues: If your Glue job runs within a VPC, there might have been temporary network connectivity issues between the Glue job and S3.

4. S3 Request Rate Limitations: Your job might have hit S3 request rate limits, especially if it's processing a large number of files simultaneously.

Recommended remediation steps:

1. Review IAM Permissions: Ensure the IAM role used by your Glue job has the necessary S3 permissions, particularly s3:GetObject for the bucket and objects being accessed.

2. Implement Retry Logic: Modify your Glue job to include robust retry mechanisms for S3 operations to handle transient failures.

3. Monitor with CloudWatch: Set up CloudWatch monitoring for your Glue streaming job to track metrics and detect issues early. Check logs for error messages, warnings, or unusual patterns.

4. Test Locally: Before deploying updates to your streaming job, test them locally using AWS Glue Docker images or the AWS Glue ETL library.

5. Optimize S3 Access Patterns: If your job accesses many small files, consider optimizing your S3 access patterns to reduce the number of API calls.

6. Consider Checkpointing: Implement proper checkpointing in your streaming job to ensure it can recover from failures without reprocessing all data.

Since restarting the job resolved the issue, it was likely a transient problem. However, implementing the above recommendations should help make your job more resilient to similar issues in the future.
Sources
Troubleshoot Amazon S3 errors from AWS SDK exceptions | AWS re:Post
Troubleshoot AWS Glue streaming job | AWS re:Post
5.2 - Spark troubleshooting and performance tuning | AWS Open Data Analytics