mirror of https://github.com/tailscale/tailscale/
tsweb: replace NewMux with a more flexible DebugHandler.
Signed-off-by: David Anderson <danderson@tailscale.com>pull/2159/head
David Anderson
3 years ago
committed by
Dave Anderson
parent
b461ba9554
commit
0022c3d2e2
@ -0,0 +1,136 @@
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// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package tsweb
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import (
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"expvar"
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"fmt"
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"html"
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"io"
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"net/http"
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"net/http/pprof"
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"net/url"
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"os"
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"runtime"
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"tailscale.com/version"
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)
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// DebugHandler is an http.Handler that serves a debugging "homepage",
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// and provides helpers to register more debug endpoints and reports.
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//
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// The rendered page consists of three sections: informational
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// key/value pairs, links to other pages, and additional
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// program-specific HTML. Callers can add to these sections using the
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// KV, URL and Section helpers respectively.
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//
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// Additionally, the Handle method offers a shorthand for correctly
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// registering debug handlers and cross-linking them from /debug/.
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type DebugHandler struct {
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mux *http.ServeMux // where this handler is registered
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kvs []func(io.Writer) // output one <li>...</li> each, see KV()
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urls []string // one <li>...</li> block with link each
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sections []func(io.Writer, *http.Request) // invoked in registration order prior to outputting </body>
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}
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// Debugger returns the DebugHandler registered on mux at /debug/,
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// creating it if necessary.
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func Debugger(mux *http.ServeMux) *DebugHandler {
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h, pat := mux.Handler(&http.Request{URL: &url.URL{Path: "/debug/"}})
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if d, ok := h.(*DebugHandler); ok && pat == "/debug/" {
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return d
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}
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ret := &DebugHandler{
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mux: mux,
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}
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mux.Handle("/debug/", ret)
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ret.KVFunc("Uptime", func() interface{} { return Uptime() })
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ret.KV("Version", version.Long)
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ret.Handle("vars", "Metrics (Go)", expvar.Handler())
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ret.Handle("varz", "Metrics (Prometheus)", http.HandlerFunc(VarzHandler))
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ret.Handle("pprof/", "pprof", http.HandlerFunc(pprof.Index))
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ret.URL("/debug/pprof/goroutine?debug=1", "Goroutines (collapsed)")
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ret.URL("/debug/pprof/goroutine?debug=2", "Goroutines (full)")
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ret.Handle("gc", "force GC", http.HandlerFunc(gcHandler))
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hostname, err := os.Hostname()
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if err == nil {
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ret.KV("Machine", hostname)
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}
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return ret
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}
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// ServeHTTP implements http.Handler.
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func (d *DebugHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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if !AllowDebugAccess(r) {
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http.Error(w, "debug access denied", http.StatusForbidden)
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return
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}
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if r.URL.Path != "/debug/" {
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// Sub-handlers are handled by the parent mux directly.
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http.NotFound(w, r)
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return
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}
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f := func(format string, args ...interface{}) { fmt.Fprintf(w, format, args...) }
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f("<html><body><h1>%s debug</h1><ul>", version.CmdName())
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for _, kv := range d.kvs {
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kv(w)
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}
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for _, url := range d.urls {
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io.WriteString(w, url)
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}
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for _, section := range d.sections {
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section(w, r)
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}
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}
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// Handle registers handler at /debug/<slug> and creates a descriptive
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// entry in /debug/ for it.
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func (d *DebugHandler) Handle(slug, desc string, handler http.Handler) {
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href := "/debug/" + slug
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d.mux.Handle(href, Protected(handler))
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d.URL(href, desc)
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}
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// KV adds a key/value list item to /debug/.
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func (d *DebugHandler) KV(k string, v interface{}) {
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val := html.EscapeString(fmt.Sprintf("%v", v))
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d.kvs = append(d.kvs, func(w io.Writer) {
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fmt.Fprintf(w, "<li><b>%s:</b> %s</li>", k, val)
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})
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}
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// KVFunc adds a key/value list item to /debug/. v is called on every
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// render of /debug/.
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func (d *DebugHandler) KVFunc(k string, v func() interface{}) {
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d.kvs = append(d.kvs, func(w io.Writer) {
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val := html.EscapeString(fmt.Sprintf("%v", v()))
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fmt.Fprintf(w, "<li><b>%s:</b> %s</li>", k, val)
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})
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}
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// URL adds a URL and description list item to /debug/.
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func (d *DebugHandler) URL(url, desc string) {
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if desc != "" {
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desc = " (" + desc + ")"
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}
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d.urls = append(d.urls, fmt.Sprintf(`<li><a href="%s">%s</a>%s</li>`, url, url, html.EscapeString(desc)))
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}
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// Section invokes f on every render of /debug/ to add supplemental
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// HTML to the page body.
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func (d *DebugHandler) Section(f func(w io.Writer, r *http.Request)) {
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d.sections = append(d.sections, f)
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}
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func gcHandler(w http.ResponseWriter, r *http.Request) {
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w.Write([]byte("running GC...\n"))
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if f, ok := w.(http.Flusher); ok {
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f.Flush()
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}
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runtime.GC()
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w.Write([]byte("Done.\n"))
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}
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@ -0,0 +1,189 @@
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// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package tsweb
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import (
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"fmt"
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"io"
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"net/http"
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"net/http/httptest"
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"strings"
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"testing"
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)
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func TestDebugger(t *testing.T) {
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mux := http.NewServeMux()
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dbg1 := Debugger(mux)
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if dbg1 == nil {
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t.Fatal("didn't get a debugger from mux")
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}
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dbg2 := Debugger(mux)
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if dbg2 != dbg1 {
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t.Fatal("Debugger returned different debuggers for the same mux")
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}
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}
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func get(m http.Handler, path, srcIP string) (int, string) {
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req := httptest.NewRequest("GET", path, nil)
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req.RemoteAddr = srcIP + ":1234"
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rec := httptest.NewRecorder()
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m.ServeHTTP(rec, req)
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return rec.Result().StatusCode, rec.Body.String()
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}
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const (
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tsIP = "100.100.100.100"
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pubIP = "8.8.8.8"
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)
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func TestDebuggerKV(t *testing.T) {
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mux := http.NewServeMux()
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dbg := Debugger(mux)
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dbg.KV("Donuts", 42)
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dbg.KV("Secret code", "hunter2")
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val := "red"
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dbg.KVFunc("Condition", func() interface{} { return val })
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code, _ := get(mux, "/debug/", pubIP)
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if code != 403 {
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t.Fatalf("debug access wasn't denied, got %v", code)
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}
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code, body := get(mux, "/debug/", tsIP)
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if code != 200 {
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t.Fatalf("debug access failed, got %v", code)
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}
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for _, want := range []string{"Donuts", "42", "Secret code", "hunter2", "Condition", "red"} {
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if !strings.Contains(body, want) {
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t.Errorf("want %q in output, not found", want)
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}
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}
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val = "green"
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code, body = get(mux, "/debug/", tsIP)
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if code != 200 {
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t.Fatalf("debug access failed, got %v", code)
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}
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for _, want := range []string{"Condition", "green"} {
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if !strings.Contains(body, want) {
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t.Errorf("want %q in output, not found", want)
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}
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}
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}
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func TestDebuggerURL(t *testing.T) {
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mux := http.NewServeMux()
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dbg := Debugger(mux)
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dbg.URL("https://www.tailscale.com", "Homepage")
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code, body := get(mux, "/debug/", tsIP)
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if code != 200 {
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t.Fatalf("debug access failed, got %v", code)
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}
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for _, want := range []string{"https://www.tailscale.com", "Homepage"} {
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if !strings.Contains(body, want) {
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t.Errorf("want %q in output, not found", want)
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}
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}
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}
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func TestDebuggerSection(t *testing.T) {
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mux := http.NewServeMux()
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dbg := Debugger(mux)
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dbg.Section(func(w io.Writer, r *http.Request) {
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fmt.Fprintf(w, "Test output %v", r.RemoteAddr)
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})
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code, body := get(mux, "/debug/", tsIP)
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if code != 200 {
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t.Fatalf("debug access failed, got %v", code)
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}
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want := `Test output 100.100.100.100:1234`
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if !strings.Contains(body, want) {
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t.Errorf("want %q in output, not found", want)
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}
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}
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func TestDebuggerHandle(t *testing.T) {
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mux := http.NewServeMux()
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dbg := Debugger(mux)
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dbg.Handle("check", "Consistency check", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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fmt.Fprintf(w, "Test output %v", r.RemoteAddr)
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}))
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code, body := get(mux, "/debug/", tsIP)
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if code != 200 {
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t.Fatalf("debug access failed, got %v", code)
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}
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for _, want := range []string{"/debug/check", "Consistency check"} {
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if !strings.Contains(body, want) {
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t.Errorf("want %q in output, not found", want)
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}
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}
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code, _ = get(mux, "/debug/check", pubIP)
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if code != 403 {
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t.Fatal("/debug/check should be protected, but isn't")
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}
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code, body = get(mux, "/debug/check", tsIP)
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if code != 200 {
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t.Fatal("/debug/check denied debug access")
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}
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want := "Test output " + tsIP
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if !strings.Contains(body, want) {
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t.Errorf("want %q in output, not found", want)
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}
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}
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func ExampleDebugHandler_Handle() {
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mux := http.NewServeMux()
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dbg := Debugger(mux)
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// Registers /debug/flushcache with the given handler, and adds a
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// link to /debug/ with the description "Flush caches".
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dbg.Handle("flushcache", "Flush caches", http.HandlerFunc(http.NotFound))
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}
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func ExampleDebugHandler_KV() {
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mux := http.NewServeMux()
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dbg := Debugger(mux)
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// Adds two list items to /debug/, showing that the condition is
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// red and there are 42 donuts.
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dbg.KV("Conditon", "red")
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dbg.KV("Donuts", 42)
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}
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func ExampleDebugHandler_KVFunc() {
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mux := http.NewServeMux()
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dbg := Debugger(mux)
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// Adds an count of page renders to /debug/. Note this example
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// isn't concurrency-safe.
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views := 0
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dbg.KVFunc("Debug pageviews", func() interface{} {
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views = views + 1
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return views
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})
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dbg.KV("Donuts", 42)
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}
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func ExampleDebugHandler_URL() {
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mux := http.NewServeMux()
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dbg := Debugger(mux)
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// Links to the Tailscale website from /debug/.
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dbg.URL("https://www.tailscale.com", "Homepage")
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}
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func ExampleDebugHandler_Section() {
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mux := http.NewServeMux()
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dbg := Debugger(mux)
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// Adds a section to /debug/ that dumps the HTTP request of the
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// visitor.
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dbg.Section(func(w io.Writer, r *http.Request) {
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io.WriteString(w, "<h3>Dump of your HTTP request</h3>")
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fmt.Fprintf(w, "<code>%#v</code>", r)
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})
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}
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