0d6e113f90
Add a NativeHistogramBucketFactor parameter to the use of `NewHistogramVec` in order to enable use of Prometheus Native Histograms. This will store automatically computed sparse buckets in CoreDNS. If a compatible Prometeus requests native histograms this data will returned instead of the static buckets. The default factor of 1.05 should provide high quality resolution data. Signed-off-by: SuperQ <superq@gmail.com>
84 lines
2.5 KiB
Go
84 lines
2.5 KiB
Go
package health
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import (
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"context"
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"net"
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"net/http"
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"time"
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"github.com/coredns/coredns/plugin"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/client_golang/prometheus/promauto"
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)
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// overloaded queries the health end point and updates a metrics showing how long it took.
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func (h *health) overloaded(ctx context.Context) {
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bypassProxy := &http.Transport{
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Proxy: nil,
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DialContext: (&net.Dialer{
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Timeout: 30 * time.Second,
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KeepAlive: 30 * time.Second,
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}).DialContext,
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ForceAttemptHTTP2: true,
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MaxIdleConns: 100,
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IdleConnTimeout: 90 * time.Second,
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TLSHandshakeTimeout: 10 * time.Second,
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ExpectContinueTimeout: 1 * time.Second,
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}
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timeout := 3 * time.Second
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client := http.Client{
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Timeout: timeout,
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Transport: bypassProxy,
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}
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req, _ := http.NewRequestWithContext(ctx, http.MethodGet, h.healthURI.String(), nil)
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tick := time.NewTicker(1 * time.Second)
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defer tick.Stop()
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for {
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select {
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case <-tick.C:
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start := time.Now()
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resp, err := client.Do(req)
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if err != nil && ctx.Err() == context.Canceled {
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// request was cancelled by parent goroutine
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return
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}
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if err != nil {
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HealthDuration.Observe(time.Since(start).Seconds())
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HealthFailures.Inc()
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log.Warningf("Local health request to %q failed: %s", req.URL.String(), err)
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continue
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}
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resp.Body.Close()
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elapsed := time.Since(start)
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HealthDuration.Observe(elapsed.Seconds())
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if elapsed > time.Second { // 1s is pretty random, but a *local* scrape taking that long isn't good
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log.Warningf("Local health request to %q took more than 1s: %s", req.URL.String(), elapsed)
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}
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case <-ctx.Done():
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return
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}
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}
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}
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var (
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// HealthDuration is the metric used for exporting how fast we can retrieve the /health endpoint.
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HealthDuration = promauto.NewHistogram(prometheus.HistogramOpts{
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Namespace: plugin.Namespace,
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Subsystem: "health",
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Name: "request_duration_seconds",
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Buckets: plugin.SlimTimeBuckets,
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NativeHistogramBucketFactor: plugin.NativeHistogramBucketFactor,
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Help: "Histogram of the time (in seconds) each request took.",
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})
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// HealthFailures is the metric used to count how many times the health request failed
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HealthFailures = promauto.NewCounter(prometheus.CounterOpts{
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Namespace: plugin.Namespace,
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Subsystem: "health",
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Name: "request_failures_total",
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Help: "The number of times the health check failed.",
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})
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)
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