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8546ff98fb
This splits Prometheus metric handlers exposed by tsweb into two modules: - `varz.Handler` exposes Prometheus metrics generated by our expvar converter; - `promvarz.Handler` combines our expvar-converted metrics and native Prometheus metrics. By default, tsweb will use the promvarz handler, however users can keep using only the expvar converter. Specifically, `tailscaled` now uses `varz.Handler` explicitly, which avoids a dependency on the (heavyweight) Prometheus client. Updates https://github.com/tailscale/corp/issues/10205 Signed-off-by: Anton Tolchanov <anton@tailscale.com>
49 lines
1.3 KiB
Go
49 lines
1.3 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package promvarz combines Prometheus metrics exported by our expvar converter
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// (tsweb/varz) with metrics exported by the official Prometheus client.
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package promvarz
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import (
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"fmt"
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"net/http"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/common/expfmt"
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"tailscale.com/tsweb/varz"
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)
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// Handler returns Prometheus metrics exported by our expvar converter
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// and the official Prometheus client.
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func Handler(w http.ResponseWriter, r *http.Request) {
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if err := gatherNativePrometheusMetrics(w); err != nil {
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w.WriteHeader(http.StatusInternalServerError)
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w.Write([]byte(err.Error()))
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return
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}
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varz.Handler(w, r)
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}
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// gatherNativePrometheusMetrics writes metrics from the default
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// metric registry in text format.
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func gatherNativePrometheusMetrics(w http.ResponseWriter) error {
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enc := expfmt.NewEncoder(w, expfmt.FmtText)
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mfs, err := prometheus.DefaultGatherer.Gather()
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if err != nil {
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return fmt.Errorf("could not gather metrics from DefaultGatherer: %w", err)
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}
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for _, mf := range mfs {
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if err := enc.Encode(mf); err != nil {
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return fmt.Errorf("could not encode metric %v: %w", mf, err)
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}
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}
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if closer, ok := enc.(expfmt.Closer); ok {
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if err := closer.Close(); err != nil {
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return err
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}
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}
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return nil
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}
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