mirror of https://github.com/k3s-io/k3s
78 lines
2.8 KiB
Go
78 lines
2.8 KiB
Go
/*
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Copyright 2019 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package metrics
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import (
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"io"
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"net/http"
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"github.com/prometheus/client_golang/prometheus/promhttp"
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)
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// These constants cause handlers serving metrics to behave as described if
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// errors are encountered.
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const (
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// Serve an HTTP status code 500 upon the first error
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// encountered. Report the error message in the body.
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HTTPErrorOnError promhttp.HandlerErrorHandling = iota
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// Ignore errors and try to serve as many metrics as possible. However,
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// if no metrics can be served, serve an HTTP status code 500 and the
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// last error message in the body. Only use this in deliberate "best
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// effort" metrics collection scenarios. In this case, it is highly
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// recommended to provide other means of detecting errors: By setting an
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// ErrorLog in HandlerOpts, the errors are logged. By providing a
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// Registry in HandlerOpts, the exposed metrics include an error counter
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// "promhttp_metric_handler_errors_total", which can be used for
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// alerts.
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ContinueOnError
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// Panic upon the first error encountered (useful for "crash only" apps).
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PanicOnError
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)
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// HandlerOpts specifies options how to serve metrics via an http.Handler. The
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// zero value of HandlerOpts is a reasonable default.
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type HandlerOpts promhttp.HandlerOpts
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func (ho *HandlerOpts) toPromhttpHandlerOpts() promhttp.HandlerOpts {
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return promhttp.HandlerOpts(*ho)
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}
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// HandlerFor returns an uninstrumented http.Handler for the provided
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// Gatherer. The behavior of the Handler is defined by the provided
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// HandlerOpts. Thus, HandlerFor is useful to create http.Handlers for custom
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// Gatherers, with non-default HandlerOpts, and/or with custom (or no)
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// instrumentation. Use the InstrumentMetricHandler function to apply the same
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// kind of instrumentation as it is used by the Handler function.
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func HandlerFor(reg Gatherer, opts HandlerOpts) http.Handler {
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return promhttp.HandlerFor(reg, opts.toPromhttpHandlerOpts())
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}
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// HandlerWithReset return an http.Handler with Reset
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func HandlerWithReset(reg KubeRegistry, opts HandlerOpts) http.Handler {
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defaultHandler := promhttp.HandlerFor(reg, opts.toPromhttpHandlerOpts())
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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if r.Method == http.MethodDelete {
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reg.Reset()
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io.WriteString(w, "metrics reset\n")
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return
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}
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defaultHandler.ServeHTTP(w, r)
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})
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}
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