HaproxyHighHttp4xxErrorRateBackend #

Too many HTTP requests with status 4xx (> 5%) on backend {{ $labels.fqdn }}/{{ $labels.backend }}

alert: HaproxyHighHttp4xxErrorRateBackend
annotations:
  description: |-
    Too many HTTP requests with status 4xx (> 5%) on backend {{ $labels.fqdn }}/{{ $labels.backend }}
      VALUE = {{ $value }}
      LABELS = {{ $labels }}    
  runbook: https://srerun.github.io/prometheus-alerts/runbooks/haproxy-exporter-v1/haproxyhighhttp4xxerrorratebackend/
  summary: HAProxy high HTTP 4xx error rate backend (instance {{ $labels.instance
    }})
expr: sum by (backend) (rate(haproxy_server_http_responses_total{code="4xx"}[1m]))
  / sum by (backend) (rate(haproxy_server_http_responses_total[1m])) > 5
for: 1m
labels:
  severity: critical

Here is a runbook for the Prometheus alert rule:

Meaning #

The HaproxyHighHttp4xxErrorRateBackend alert is triggered when the rate of HTTP requests with status 4xx (client errors) exceeds 5% of the total HTTP requests on a specific backend server. This indicates that there may be an issue with the backend server or the requests being sent to it.

Impact #

• High error rates can lead to a poor user experience and reduced confidence in the application.
• Increased error rates can also lead to increased latency and decreased performance.
• Prolonged high error rates can also lead to resource wasting, as requests are being sent to a backend that is not able to process them correctly.

Diagnosis #

• Check the HAProxy logs to identify the specific 4xx error codes being returned and the URLs被affected.
• Investigate the backend server logs to determine the root cause of the errors.
• Check for any recent changes to the backend server or application code that may be contributing to the errors.
• Verify that the backend server is properly configured and has sufficient resources to handle the incoming requests.
• Check for any issues with the network connectivity between the HAProxy server and the backend server.

Mitigation #

• Investigate and resolve the root cause of the 4xx errors on the backend server.
• Implement retry logic on the HAProxy server to retry failed requests.
• Consider implementing circuit breakers to prevent further requests from being sent to the backend server until the issue is resolved.
• Check for any opportunities to optimize the backend server or application code to reduce the error rate.
• Verify that the HAProxy server is properly configured to handle the incoming requests and that the backend server is properly configured to handle the traffic.

Note: The runbook is just a template and should be tailored to the specific environment and requirements of the organization.