504 Gateway Timeout on Elastic Beanstalk PHP

For your PHP application on Elastic Beanstalk experiencing 504 Gateway Timeout errors during long OCR processing, there are several approaches to resolve this issue:

1. Adjust PHP execution time limit: Your PHP script is likely hitting the default max_execution_time limit. You should increase this setting in your Elastic Beanstalk configuration using an .ebextensions file:

option_settings:
aws:elasticbeanstalk:container:php:phpini:
max_execution_time: 300

This will increase the PHP execution time limit to 300 seconds (5 minutes) or higher as needed for your OCR processing.

2. Implement asynchronous processing: Instead of processing the OCR request synchronously, consider:

• Using a queue system (like SQS) to offload the processing
• Implementing a background job that handles the OCR processing
• Returning an immediate response to the user and providing a way to check the status later

3. Verify all timeout settings: Ensure you've properly configured all relevant timeout settings:

• PHP's max_execution_time
• Nginx timeouts (proxy_read_timeout, fastcgi_read_timeout)
• Any application-level timeouts

4. Monitor resource usage: Check if your application is hitting resource limits during processing:

• Review CloudWatch metrics for CPU, memory usage
• Look for "Memory limit exceeded" or similar errors in your logs

5. Consider AWS Lambda or Step Functions: For very long-running processes, you might want to move the OCR processing out of your PHP application entirely and use AWS Lambda or Step Functions, which can handle longer execution times.

Best practices for handling long-running PHP processes on Elastic Beanstalk:

• Always process long-running tasks asynchronously
• Use a worker environment for background processing
• Implement proper error handling and retry mechanisms
• Consider breaking down the processing into smaller chunks
• Provide status updates to users during long-running operations
  Sources
  Using the Elastic Beanstalk PHP platform - AWS Elastic Beanstalk
  Diagnose and resolve performance issues in my Amazon ECS-hosted applications | AWS re:Post