Alert thresholds depend on the nature of your applications. Some queries may have arbitrary tolerance thresholds. Building an efficient monitoring platform takes time. 😉
3 Prometheus alerting rules for Caddy. Exported via Embedded exporter. These rules cover critical and warning conditions — copy and paste the YAML into your Prometheus configuration.
groups:
- name: EmbeddedExporter
rules:
- alert: CaddyReverseProxyDown
expr: caddy_reverse_proxy_upstreams_healthy == 0
for: 0m
labels:
severity: critical
annotations:
summary: Caddy Reverse Proxy Down (instance {{ $labels.instance }})
description: "Caddy reverse proxy upstream {{ $labels.upstream }} is unhealthy\n VALUE = {{ $value }}\n LABELS = {{ $labels }}"
- alert: CaddyHighHTTP4xxErrorRateService
expr: sum(rate(caddy_http_request_duration_seconds_count{code=~"4.."}[3m])) by (instance) / sum(rate(caddy_http_request_duration_seconds_count[3m])) by (instance) * 100 > 5 and sum(rate(caddy_http_request_duration_seconds_count[3m])) by (instance) > 0
for: 1m
labels:
severity: critical
annotations:
summary: Caddy high HTTP 4xx error rate service (instance {{ $labels.instance }})
description: "Caddy service 4xx error rate is above 5%\n VALUE = {{ $value }}\n LABELS = {{ $labels }}"
- alert: CaddyHighHTTP5xxErrorRateService
expr: sum(rate(caddy_http_request_duration_seconds_count{code=~"5.."}[3m])) by (instance) / sum(rate(caddy_http_request_duration_seconds_count[3m])) by (instance) * 100 > 5 and sum(rate(caddy_http_request_duration_seconds_count[3m])) by (instance) > 0
for: 1m
labels:
severity: critical
annotations:
summary: Caddy high HTTP 5xx error rate service (instance {{ $labels.instance }})
description: "Caddy service 5xx error rate is above 5%\n VALUE = {{ $value }}\n LABELS = {{ $labels }}" wget https://raw.githubusercontent.com/samber/awesome-prometheus-alerts/refs/heads/master/dist/rules/caddy/embedded-exporter.yml
Caddy reverse proxy upstream {{ $labels.upstream }} is unhealthy
- alert: CaddyReverseProxyDown
expr: caddy_reverse_proxy_upstreams_healthy == 0
for: 0m
labels:
severity: critical
annotations:
summary: Caddy Reverse Proxy Down (instance {{ $labels.instance }})
description: "Caddy reverse proxy upstream {{ $labels.upstream }} is unhealthy\n VALUE = {{ $value }}\n LABELS = {{ $labels }}" Caddy service 4xx error rate is above 5%
- alert: CaddyHighHTTP4xxErrorRateService
expr: sum(rate(caddy_http_request_duration_seconds_count{code=~"4.."}[3m])) by (instance) / sum(rate(caddy_http_request_duration_seconds_count[3m])) by (instance) * 100 > 5 and sum(rate(caddy_http_request_duration_seconds_count[3m])) by (instance) > 0
for: 1m
labels:
severity: critical
annotations:
summary: Caddy high HTTP 4xx error rate service (instance {{ $labels.instance }})
description: "Caddy service 4xx error rate is above 5%\n VALUE = {{ $value }}\n LABELS = {{ $labels }}" Caddy service 5xx error rate is above 5%
- alert: CaddyHighHTTP5xxErrorRateService
expr: sum(rate(caddy_http_request_duration_seconds_count{code=~"5.."}[3m])) by (instance) / sum(rate(caddy_http_request_duration_seconds_count[3m])) by (instance) * 100 > 5 and sum(rate(caddy_http_request_duration_seconds_count[3m])) by (instance) > 0
for: 1m
labels:
severity: critical
annotations:
summary: Caddy high HTTP 5xx error rate service (instance {{ $labels.instance }})
description: "Caddy service 5xx error rate is above 5%\n VALUE = {{ $value }}\n LABELS = {{ $labels }}"