How to use Prometheus to monitor database agent performance?

To monitor database agent performance using Prometheus, you need to follow these steps:

1. Expose Metrics from the Database Agent:
   The database agent (e.g., MySQL exporter, PostgreSQL exporter, or a custom agent) must expose performance metrics in Prometheus' exposition format (usually via HTTP at /metrics). Most official database exporters already support this.

   Example: If you're using a MySQL exporter, it will expose metrics like mysql_up, mysql_global_status_queries_total, and mysql_global_status_threads_running at an HTTP endpoint.

2. Configure Prometheus to Scrape Metrics:
   In Prometheus' configuration file (prometheus.yml), add a scrape_config entry for the database agent's metrics endpoint.

   Example Configuration:

   scrape_configs:
     - job_name: 'database_agent'
       static_configs:
         - targets: ['<agent-host>:<port>']  # e.g., 'localhost:9104' for MySQL exporter
   

3. Verify Metrics in Prometheus UI:
   After restarting Prometheus, check the Targets page to ensure the database agent is being scraped successfully. Then, query metrics in the Graph or PromQL interface.

   Example Query:

   • mysql_global_status_queries_total (total queries)
   • rate(mysql_global_status_queries_total[5m]) (queries per second over 5 minutes)
   • up{job="database_agent"} (checks if the agent is alive)

4. Set Up Alerts (Optional):
   Use Prometheus' Alertmanager to define alerting rules for critical conditions, such as high query latency or agent downtime.

   Example Alert Rule:

   groups:
     - name: database_alerts
       rules:
         - alert: HighQueryLatency
           expr: rate(mysql_global_status_queries_total[5m]) > 1000
           for: 5m
           labels:
             severity: warning
           annotations:
             summary: "High query rate detected"
             description: "Database agent is handling {{ $value }} queries/sec."
   

5. Visualize Metrics (Optional):
   Use Grafana to create dashboards for real-time monitoring of database agent performance. Import pre-built dashboards (e.g., MySQL/PostgreSQL monitoring dashboards) or build custom ones.

   Recommended Tencent Cloud Service:
   For managed monitoring and alerting, consider Tencent Cloud Monitoring (CM) or Tencent Cloud CLS (Cloud Log Service) to integrate with Prometheus data for enhanced observability.

By following these steps, you can effectively monitor database agent performance using Prometheus, ensuring timely detection of issues and optimized database operations.