a412255ad1
Add prometheus metrics to the cache handler. This just used prometheus, if the metrics middleware does not setup the handler, there is nobody reading these metrics, but they are still reported. Seems the simplest solution while keeping the whole middleware separation in tact.
prometheus
This module enables prometheus metrics for CoreDNS. The default location for the metrics is
localhost:9135. The metrics path is fixed to /metrics.
The following metrics are exported:
- coredns_dns_request_count_total
- coredns_dns_request_duration_seconds
- coredns_dns_response_size_bytes
- coredns_dns_response_rcode_count_total
Each counter has a label zone which is the zonename used for the request/response. and a label
qtype which old the query type. The dns_request_count_total has an extra label proto which
holds the transport of the response ("udp" or "tcp"). The response_rcode_count_total has an extra
label rcode which holds the rcode of the response.
If monitoring is enabled queries that do not enter the middleware chain are exported under the fake domain "dropped" (without a closing dot).
Restarting CoreDNS will stop the monitoring. This is a bug. Also this upstream Caddy bug.
Syntax
prometheus
For each zone that you want to see metrics for.
It optionally takes an address where the metrics are exported, the default
is localhost:9135. The metrics path is fixed to /metrics.