Issue Summary:
On June 18th, 2024, from 10:00 AM to 11:00 AM SAT, our web application experienced a significant outage due to a load balancer error. Users encountered HTTP 500 Internal Server Errors, impacting approximately 40% of our user base. The root cause was a communication issue between the load balancer and backend servers.
Timeline: (SAT)
- 10:00 AM: An engineer noticed increased error rates in the logs.
- 10:02 AM: The engineer notified the team via Discord.
- 10:05 AM: Initial investigation began, focusing on server logs and load balancer health checks.
- 10:15 AM: Identified intermittent communication failures between the load balancer and backend servers.
- 10:20 AM: The initial hypothesis formed was that the issue was related to network connectivity or misconfigured load balancer settings.
- 10:30 AM: Engineers investigated potential connectivity issues but found none.
- 10:40 AM: Load balancer configuration reviewed and identified a recent update causing the issue.
- 10:45 AM: Reverted load balancer settings to the previous stable configuration.
- 10:50 AM: Verified that the web application was operational and error-free.
- 11:00 AM: Full service restored and monitoring confirmed stability.
Root Cause and Resolution:
The outage was caused by a misconfiguration in the load balancer settings during a recent update, leading to communication failures with backend servers. The issue was resolved by reverting the load balancer configuration to its previous stable state.
Corrective and Preventive Measures:
Improvement Areas:
- Implement pre-deployment configuration validation.
- Enhance monitoring to detect configuration issues promptly.
- Increase redundancy to mitigate single points of failure.
Specific Tasks:
- Deploy Configuration Validation Tools: Integrate tools to validate load balancer configurations before deployment.
- Training Sessions: Conduct training for engineers on load balancer management best practices.
- Enhanced Monitoring: Implement more detailed health checks and alerts to quickly identify and resolve similar issues.
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