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Published: Mar 25, 2018 License: Apache-2.0 Imports: 12 Imported by: 0




health - enables a health check endpoint.


By enabling health any plugin that implements healt.Healther interface will be queried for it's health. The combined health is exported, by default, on port 8080/health .


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 CoreDNS is healthy. It returns a 503. health periodically (1s) polls plugin that exports health information. If any of the plugin signals that it is unhealthy, the server will go unhealthy too. Each plugin that supports health checks has a section "Health" in their README.

More options can be set with this extended syntax:

health [ADDRESS] {
    lameduck DURATION
  • Where lameduck will make the process unhealthy then wait for DURATION before the process shuts down.

If you have multiple Server Block and need to export health for each of the plugins, you must run health endpoints on different ports:

com {
    health :8080

net {
    health :8081


Any plugin that implements the Healther interface will be used to report health.


If monitoring is enabled (via the prometheus directive) then the following metric is exported:

  • coredns_health_request_duration_seconds{} - duration to process a /health query. As this should be a local operation it should be fast. A (large) increases in this duration indicates the CoreDNS process is having trouble keeping up with its query load.


Run another health endpoint on http://localhost:8091.

. {
    health localhost:8091

Set a lameduck duration of 1 second:

. {
    health localhost:8092 {
        lameduck 1s



Package health implements an HTTP handler that responds to health checks.



This section is empty.


View Source
var (
	// HealthDuration is the metric used for exporting how fast we can retrieve the /health endpoint.
	HealthDuration = prometheus.NewHistogram(prometheus.HistogramOpts{
		Namespace: plugin.Namespace,
		Subsystem: "health",
		Name:      "request_duration_seconds",
		Buckets:   plugin.TimeBuckets,
		Help:      "Histogram of the time (in seconds) each request took.",


This section is empty.


type Healther

type Healther interface {
	// Health returns a boolean indicating the health status of a plugin.
	// False indicates unhealthy.
	Health() bool

Healther interface needs to be implemented by each plugin willing to provide healthhceck information to the health plugin. Note this method should return quickly, i.e. just checking a boolean status, as it is called every second from the health plugin.

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