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https://github.com/tailscale/tailscale.git
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92 lines
2.6 KiB
Go
92 lines
2.6 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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//go:build linux
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package main
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import (
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"fmt"
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"io"
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"log"
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"net"
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"net/http"
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"tailscale.com/client/tailscale"
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"tailscale.com/client/tailscale/apitype"
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)
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// metrics is a simple metrics HTTP server, if enabled it forwards requests to
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// the tailscaled's LocalAPI usermetrics endpoint at /localapi/v0/usermetrics.
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type metrics struct {
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debugEndpoint string
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lc *tailscale.LocalClient
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}
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func proxy(w http.ResponseWriter, r *http.Request, url string, do func(*http.Request) (*http.Response, error)) {
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req, err := http.NewRequestWithContext(r.Context(), r.Method, url, r.Body)
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if err != nil {
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http.Error(w, fmt.Sprintf("failed to construct request: %s", err), http.StatusInternalServerError)
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return
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}
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req.Header = r.Header.Clone()
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resp, err := do(req)
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if err != nil {
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http.Error(w, fmt.Sprintf("failed to proxy request: %s", err), http.StatusInternalServerError)
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return
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}
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defer resp.Body.Close()
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for key, val := range resp.Header {
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for _, v := range val {
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w.Header().Add(key, v)
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}
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}
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w.WriteHeader(resp.StatusCode)
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if _, err := io.Copy(w, resp.Body); err != nil {
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http.Error(w, err.Error(), http.StatusInternalServerError)
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}
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}
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func (m *metrics) handleMetrics(w http.ResponseWriter, r *http.Request) {
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localAPIURL := "http://" + apitype.LocalAPIHost + "/localapi/v0/usermetrics"
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proxy(w, r, localAPIURL, m.lc.DoLocalRequest)
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}
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func (m *metrics) handleDebug(w http.ResponseWriter, r *http.Request) {
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if m.debugEndpoint == "" {
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http.Error(w, "debug endpoint not configured", http.StatusNotFound)
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return
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}
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debugURL := "http://" + m.debugEndpoint + r.URL.Path
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proxy(w, r, debugURL, http.DefaultClient.Do)
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}
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// runMetrics runs a simple HTTP metrics endpoint at <addr>/metrics, forwarding
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// requests to tailscaled's /localapi/v0/usermetrics API.
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//
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// In 1.78.x and 1.80.x, it also proxies debug paths to tailscaled's debug
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// endpoint if configured to ease migration for a breaking change serving user
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// metrics instead of debug metrics on the "metrics" port.
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func runMetrics(addr string, m *metrics) {
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ln, err := net.Listen("tcp", addr)
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if err != nil {
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log.Fatalf("error listening on the provided metrics endpoint address %q: %v", addr, err)
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}
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mux := http.NewServeMux()
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mux.HandleFunc("GET /metrics", m.handleMetrics)
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mux.HandleFunc("/debug/", m.handleDebug) // TODO(tomhjp): Remove for 1.82.0 release.
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log.Printf("Running metrics endpoint at %s/metrics", addr)
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ms := &http.Server{Handler: mux}
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go func() {
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if err := ms.Serve(ln); err != nil {
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log.Fatalf("failed running metrics endpoint: %v", err)
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}
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}()
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}
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