Resolving Prometheus Pod Crashing Issue in Production Environment

Problem:

The client reported an issue where the Prometheus pod was crashing in the production environment. The error logs indicated a variety of issues including “Terminated Reason: Error” and messages about unhealthy blocks and existing lock files. The specific error message highlighted was:

Last State: Terminated Reason: Error Message: und healthy block” mint=1680069600000 maxt=1680091200000 ulid=01GWPY8332RWJAPSFZ8KNAJQ9H ts=2023-03-31T06:46:07.776Z

Additionally, the logs mentioned:

caller=repair.go:56 level=info component=tsdb msg=”Found healthy block” mint=1680098400000 maxt=1680105600000 ulid=01GWQ501H1B768DP28TZJC2KEG

Other messages in the log detailed various stopping components and issues with resource unavailability.

Process:

Upon receiving the error report, the experts requested the Prometheus configuration files, specifically the “values” file if the deployment was managed via Helm. A live session with the client to expedite the resolution was arranged.

During the meeting the experts performed a detailed analysis and identified multiple potential root causes and corresponding solutions:

1. Stopping Scrape Manager:
   • Checked Prometheus logs for error messages.
   • Verified the Prometheus configuration file, especially the scrape_configs section.
   • Ensured network connectivity between Prometheus and its scrape targets.
   • Advised restarting the Prometheus server and explicitly restarting the scrape manager using curl -XPOST http://localhost:9090/-/reload.
2. Unhealthy Block Errors:
   • Examined Prometheus logs for any error messages.
   • Used promtool check tsdb --all-blocks to verify the integrity of Prometheus data.
   • Recommended deleting any corrupted blocks detected by promtool and restarting Prometheus.
   • Checked disk space and memory usage to ensure there was sufficient capacity for Prometheus.
   • Reviewed the data ingestion process to ensure that the targets weren’t overloading Prometheus, suggesting adjustments to the scrape interval or implementing rate limiting if necessary.
3. Unexpected Error in K8s Client Runtime:
   • Verified that Prometheus had the necessary permissions on the entry point, checking login credentials or tokens.
4. Storage Class Configuration:
   • Confirmed that the appropriate storage class (Azure disks) was being used.

Solution:

The troubleshooting process involved a step-by-step approach to identify and rectify the configuration and resource issues causing the Prometheus pod to crash. Key actions included:

• Adjusting the Prometheus configuration file.
• Ensuring network and storage configurations were optimal.
• Verifying data integrity and clearing corrupted blocks.
• Enhancing resource allocation to handle the data load efficiently.

The issue with the crashing Prometheus pod was resolved through a series of targeted actions based on log analysis and configuration review. The client was advised to monitor the environment. This proactive approach ensured that Prometheus operated smoothly in the production environment, maintaining the reliability of their monitoring infrastructure.

Conclusion:

Following our detailed investigation and live troubleshooting session, the Prometheus pod crashing issue was effectively resolved. The primary causes were identified as misconfigurations and resource constraints. By refining the Prometheus configuration, ensuring proper network and storage setups, and verifying data integrity, it was possible to stabilize the system. The experts’ recommendations and adjustments led to a seamless operation of Prometheus in the production environment.