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48059a6c3e
* plugin/health: add 'overloaded metrics' Query our on health endpoint and record (and export as a metric) the time it takes. The Get has a 5s timeout, that, when reached, will set the metric duration to 5s. The actually call "I'm I overloaded" is left to an external entity. * README * golint and govet * and the tests
45 lines
1.2 KiB
Markdown
45 lines
1.2 KiB
Markdown
# health
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## Name
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*health* - enables a health check endpoint.
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## Description
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By enabling *health* any plugin that implements it will be queried for it's health. The combined
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health is exported, by default, on port 8080/health .
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## Syntax
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~~~
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health [ADDRESS]
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~~~
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Optionally takes an address; the default is `:8080`. The health path is fixed to `/health`. The
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health endpoint returns a 200 response code and the word "OK" when CoreDNS is healthy. It returns
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a 503. *health* periodically (1s) polls plugin that exports health information. If any of the
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plugin signals that it is unhealthy, the server will go unhealthy too. Each plugin that
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supports health checks has a section "Health" in their README.
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## Plugins
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Any plugin that implements the Healther interface will be used to report health.
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## Metrics
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If monitoring is enabled (via the *prometheus* directive) then the following metric is exported:
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* `coredns_health_request_duration_seconds{}` - duration to process a /health query. As this should
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be a local operation it should be fast. A (large) increases in this duration indicates the
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CoreDNS process is having trouble keeping up.
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## Examples
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Run another health endpoint on http://localhost:8091.
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~~~ corefile
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. {
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health localhost:8091
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}
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~~~
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