Metrics

This module enables prometheus metrics for Caddy v2 (with custom-labels through HTTP Response Headers).

Build

Use the docker file to build caddy docker image.

docker build -t caddy .

Use

You'll need to put this module early in the chain, so that the duration histogram actually makes sense. I've put it at number 0. In your Caddyfile, at global section:

{
    debug
    order prometheus first
}

For each virtual host that you want to see metrics for, these are the (optional) parameters that can be used:

• use_caddy_addr - causes metrics to be exposed at the same address:port as Caddy itself. This can not be specified at the same time as address.
• address - the address where the metrics are exposed, the default is localhost:9180
• path - the path to serve collected metrics from, the default is /metrics
• hostname - the host parameter that can be found in the exported metrics, this defaults to the label specified for the server block
• label - Custom label to add on all metrics. This directive can be used multiple times.
  You should specify a label name and a value.
  The value is a placeholder {>HEADER-NAME} and can be used to extract value from response headers.
  Usage: label route_name {>X-Route-Name}

Sample Config

{
    debug
    order prometheus first
}

localhost:80 {
	@path1 {
        path /path1
    }

	@path2 {
        path /path2
    }

    handle @path1 {
        respond "Hello path1" 200

        header {
            "X-Route-Name" "/path1"
        }
    }

    handle @path2 {
        header {
                "X-Route-Name" "/path2"
        }

        respond "Hello path2" 200
    }

    prometheus {
        address 0.0.0.0:2081
        path    /metrics
        label server {>Server}
        label route_name {>X-Route-Name}
    }

    #metrics /metrics
}

Metrics

The following metrics are exported:

• caddy_http_request_count_total{host, family, proto, ...labels}
• caddy_http_request_duration_seconds{host, family, proto, ...labels}
• caddy_http_response_latency_seconds{host, family, proto, status, ...labels}
• caddy_http_response_size_bytes{host, family, proto, status, ...labels}
• caddy_http_response_status_count_total{host, family, proto, status, ...labels}

Each metric has the following labels:

• host which is the hostname used for the request/response,
• family which is the protocol family, either 1 (IP version 4) or 2 (IP version 6),
• proto which is the HTTP protocol major and minor version used: 1.x or 2 signifying HTTP/1.x or HTTP/2.

The response_* metrics have an extra label status which holds the status code.