Caddy

Prometheus Metrics

Caddy is a powerful, extensible web server with automatic HTTPS.

Prometheus Metrics

Service Configuration

Caddy 2 includes native Prometheus support, but metrics must be explicitly enabled.

Option 1: Using the Caddyfile

Add the metrics directive inside your servers block:

{
    servers {
        metrics
    }
}

Option 2: Using the command-line flag

Start Caddy with the --metrics flag:

caddy run --metrics

Once enabled, metrics are available at http://localhost:2019/metrics.

Glouton Configuration

Linux

sudo tee /etc/glouton/conf.d/99-caddy.conf > /dev/null << 'EOF'
metric:
  prometheus:
    targets:
      - url: "http://localhost:2019/metrics"
        name: "caddy"
        allow_metrics:
          - "caddy_http_requests_total"
          - "caddy_http_request_duration_seconds*"
          - "caddy_http_response_size_bytes*"
          - "caddy_reverse_proxy_upstreams_healthy"
EOF

Windows

Create or edit C:\ProgramData\glouton\conf.d\99-caddy.conf:

metric:
  prometheus:
    targets:
      - url: "http://localhost:2019/metrics"
        name: "caddy"
        allow_metrics:
          - "caddy_http_requests_total"
          - "caddy_http_request_duration_seconds*"
          - "caddy_http_response_size_bytes*"
          - "caddy_reverse_proxy_upstreams_healthy"

Glouton automatically detects configuration changes.

Customize collected metrics

The metrics below are our recommended defaults. You can adjust the allow_metrics list to include any metric from Caddy’s metrics reference, or use deny_metrics to exclude specific ones. See Metrics Filtering for details.

Metric	Description
caddy_http_requests_total	Total number of HTTP requests handled by Caddy
caddy_http_request_duration_seconds	Histogram of HTTP request durations in seconds
caddy_http_response_size_bytes	Histogram of HTTP response body sizes in bytes
caddy_reverse_proxy_upstreams_healthy	Number of healthy upstream backends for the reverse proxy