Postmortem: Server Downtime on August 24th

Incident Overview

Start Time: August 24th, 00:08 UTC
End Time: August 24th, 03:10 UTC

The server experienced a significant outage beginning at 00:08 UTC, which lasted until 03:10 UTC, totaling approximately 3 hours and 2 minutes of downtime.

Impact

• Inaccessible services hosted on the affected server
• Disruption of user access and potential data transfer issues
• System stability was compromised due to proxy management failure

Cause

The primary cause of the outage was identified as a failure in the Nginx Proxy Manager. Specifically, it broke due to issues with Let's Encrypt-based certificates. The broken certificates caused the proxy manager to malfunction, leading to the entire system becoming inaccessible.

Note: The exact root cause remains uncertain, but the failure of certificate renewal or validation appears to be a critical factor.

Timeline

Time (UTC)	Event
00:08	Proxy manager failure detected; system becomes inaccessible
~00:08 - 02:40	Attempted to deploy alternative proxy solutions (Traefik, Caddy, Nginx Proxy Manager Plus)
02:40	Abandoned alternative deployment attempts after ~2.5 hours
02:40 - 03:10	Installed a fresh copy of Nginx Proxy Manager on a new LXC container and reconfigured from scratch
03:10	Services restored; system fully operational

Resolution & Actions Taken

1. Failed Attempts with Alternative Proxy Solutions
   Spent approximately 2.5 hours trying to deploy and configure Traefik, Caddy, and Nginx Proxy Manager Plus. These efforts were unsuccessful, leading to delays in restoring service.

2. Fresh Install of Nginx Proxy Manager
   Decided to start from scratch by deploying a new instance of Nginx Proxy Manager on a new LXC container. This involved:

   • Setting up a new container environment
   • Installing Nginx Proxy Manager anew
   • Reconfiguring proxy and SSL certificates via cloudflare's SSL provider

   This approach successfully restored service and stabilized the environment.

Lessons Learned

• Certificate Management: Automated certificate renewal processes can cause system failures if not properly monitored or if certificate validation fails unexpectedly.
• Backup & Recovery: Maintaining backups of configuration and certificates could reduce downtime during such incidents.
• Testing Alternative Solutions: Prolonged attempts to deploy alternative proxy solutions highlight the importance of testing and validation in staging environments before production deployment.
• Monitoring & Alerts: Enhanced monitoring and alerting for certificate expiry or proxy failures could enable quicker response times.

Next Steps

• Investigate the root cause of the Let's Encrypt certificate failure to prevent recurrence.
• Implement regular backups of configurations and certificates.
• Improve monitoring for SSL certificate health and proxy server status.
• Document and test fallback procedures for proxy management failures.
• Review and optimize deployment procedures for proxy solutions.

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Prepared by: Kneesox - Shiro
Date: 08/24/25