2023-01-27 21:37:20 +00:00
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// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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2021-07-13 05:04:16 +00:00
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// The derpprobe binary probes derpers.
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2023-01-27 14:49:50 +00:00
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package main
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2021-07-13 05:04:16 +00:00
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import (
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2023-01-27 14:49:50 +00:00
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"expvar"
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2021-07-13 05:04:16 +00:00
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"flag"
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"fmt"
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"html"
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"io"
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"log"
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"net/http"
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"sort"
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"time"
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2023-01-27 14:49:50 +00:00
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"tailscale.com/prober"
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"tailscale.com/tsweb"
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2021-07-13 05:04:16 +00:00
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)
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var (
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derpMapURL = flag.String("derp-map", "https://login.tailscale.com/derpmap/default", "URL to DERP map (https:// or file://)")
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listen = flag.String("listen", ":8030", "HTTP listen address")
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2022-11-24 00:09:24 +00:00
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probeOnce = flag.Bool("once", false, "probe once and print results, then exit; ignores the listen flag")
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2023-01-27 14:49:50 +00:00
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interval = flag.Duration("interval", 15*time.Second, "probe interval")
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2021-07-13 05:04:16 +00:00
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)
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func main() {
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flag.Parse()
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2022-03-01 04:13:33 +00:00
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2023-01-27 14:49:50 +00:00
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p := prober.New().WithSpread(true).WithOnce(*probeOnce)
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dp, err := prober.DERP(p, *derpMapURL, *interval, *interval, *interval)
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if err != nil {
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log.Fatal(err)
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}
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p.Run("derpmap-probe", *interval, nil, dp.ProbeMap)
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2022-03-01 04:13:33 +00:00
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2022-11-24 00:09:24 +00:00
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if *probeOnce {
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log.Printf("Waiting for all probes (may take up to 1m)")
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p.Wait()
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st := getOverallStatus(p)
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2022-11-24 00:09:24 +00:00
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for _, s := range st.good {
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log.Printf("good: %s", s)
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}
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for _, s := range st.bad {
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log.Printf("bad: %s", s)
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}
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return
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}
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2023-01-27 14:49:50 +00:00
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mux := http.NewServeMux()
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tsweb.Debugger(mux)
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expvar.Publish("derpprobe", p.Expvar())
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mux.HandleFunc("/", http.HandlerFunc(serveFunc(p)))
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log.Fatal(http.ListenAndServe(*listen, mux))
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2022-01-26 19:58:56 +00:00
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}
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2021-07-13 05:04:16 +00:00
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type overallStatus struct {
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good, bad []string
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}
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2022-03-16 23:27:57 +00:00
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func (st *overallStatus) addBadf(format string, a ...any) {
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2021-07-13 05:04:16 +00:00
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st.bad = append(st.bad, fmt.Sprintf(format, a...))
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}
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2022-03-16 23:27:57 +00:00
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func (st *overallStatus) addGoodf(format string, a ...any) {
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2021-07-13 05:04:16 +00:00
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st.good = append(st.good, fmt.Sprintf(format, a...))
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}
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2023-01-27 14:49:50 +00:00
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func getOverallStatus(p *prober.Prober) (o overallStatus) {
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for p, i := range p.ProbeInfo() {
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if i.End.IsZero() {
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// Do not show probes that have not finished yet.
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2022-01-26 19:58:56 +00:00
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continue
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}
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2023-01-27 14:49:50 +00:00
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if i.Result {
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o.addGoodf("%s: %s", p, i.Latency)
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} else {
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o.addBadf("%s: %s", p, i.Error)
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2022-01-26 19:58:56 +00:00
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}
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}
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2023-01-27 14:49:50 +00:00
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sort.Strings(o.bad)
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sort.Strings(o.good)
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return
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}
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2023-01-27 14:49:50 +00:00
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func serveFunc(p *prober.Prober) func(w http.ResponseWriter, r *http.Request) {
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return func(w http.ResponseWriter, r *http.Request) {
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st := getOverallStatus(p)
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summary := "All good"
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if (float64(len(st.bad)) / float64(len(st.bad)+len(st.good))) > 0.25 {
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// Returning a 500 allows monitoring this server externally and configuring
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// an alert on HTTP response code.
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w.WriteHeader(500)
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summary = fmt.Sprintf("%d problems", len(st.bad))
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}
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2022-01-26 19:58:56 +00:00
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2023-01-27 14:49:50 +00:00
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io.WriteString(w, "<html><head><style>.bad { font-weight: bold; color: #700; }</style></head>\n")
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fmt.Fprintf(w, "<body><h1>derp probe</h1>\n%s:<ul>", summary)
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for _, s := range st.bad {
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fmt.Fprintf(w, "<li class=bad>%s</li>\n", html.EscapeString(s))
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}
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2023-01-27 14:49:50 +00:00
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for _, s := range st.good {
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fmt.Fprintf(w, "<li>%s</li>\n", html.EscapeString(s))
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}
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2023-01-27 14:49:50 +00:00
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io.WriteString(w, "</ul></body></html>\n")
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}
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}
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