COREDNS-HEALTH(7) CoreDNS Plugins COREDNS-HEALTH(7) NAME health - enables a health check endpoint. DESCRIPTION Enabled process wide health endpoint. When CoreDNS is up and running this returns a 200 OK HTTP status code. The health is exported, by default, on port 8080/health. SYNTAX health [ADDRESS] Optionally takes an address; the default is :8080. The health path is fixed to /health. The health endpoint returns a 200 response code and the word "OK" when this server is healthy. An extra option can be set with this extended syntax: health [ADDRESS] { lameduck DURATION } * Where lameduck will delay shutdown for DURATION. /health will still an- swer 200 OK. Note: The ready plugin will not answer OK while CoreDNS is in lame duck mode prior to shutdown. If you have multiple Server Blocks, health can only be enabled in one of them (as it is process wide). If you really need multiple endpoints, you must run health endpoints on different ports: com { whoami health :8080 } net { erratic health :8081 } Doing this is supported but both endpoints ":8080" and ":8081" will export the exact same health. METRICS If monitoring is enabled (via the prometheus plugin) then the following metrics are exported: * coredns_health_request_duration_seconds{} - The health plugin performs a self health check once per second on the /health endpoint. This met- ric is the duration to process that request. As this is a local opera- tion it should be fast. A (large) increase in this duration indicates the CoreDNS process is having trouble keeping up with its query load. * coredns_health_request_failures_total{} - The number of times the self health check failed. Note that these metrics do not have a server label, because being over- loaded is a symptom of the running process, not a specific server. EXAMPLES Run another health endpoint on http://localhost:8091 <http://local- host:8091>. . { health localhost:8091 } Set a lame duck duration of 1 second: . { health localhost:8092 { lameduck 1s } } CoreDNS March 2026 COREDNS-HEALTH(7)
NAME | DESCRIPTION | SYNTAX | METRICS | EXAMPLES
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