cmd/tailscale/cli: prefix all --help usages with "tailscale ...", some tidying

Also capitalises the start of all ShortHelp, allows subcommands to be hidden
with a "HIDDEN: " prefix in their ShortHelp, and adds a TS_DUMP_HELP envknob
to look at all --help messages together.

Fixes #11664

Signed-off-by: Paul Scott <paul@tailscale.com>

cmd/tailscale/cli/debug.go

@@ -45,9 +45,10 @@ import (
 )
 
 var debugCmd = &ffcli.Command{
-	Name:     "debug",
-	Exec:     runDebug,
-	LongHelp: `"tailscale debug" contains misc debug facilities; it is not a stable interface.`,
+	Name:       "debug",
+	Exec:       runDebug,
+	ShortUsage: "tailscale debug <debug-flags | subcommand>",
+	LongHelp:   `HIDDEN: "tailscale debug" contains misc debug facilities; it is not a stable interface.`,
 	FlagSet: (func() *flag.FlagSet {
 		fs := newFlagSet("debug")
 		fs.StringVar(&debugArgs.file, "file", "", "get, delete:NAME, or NAME")
@@ -58,15 +59,16 @@ var debugCmd = &ffcli.Command{
 	})(),
 	Subcommands: []*ffcli.Command{
 		{
-			Name:      "derp-map",
-			Exec:      runDERPMap,
-			ShortHelp: "print DERP map",
+			Name:       "derp-map",
+			ShortUsage: "tailscale debug derp-map",
+			Exec:       runDERPMap,
+			ShortHelp:  "Print DERP map",
 		},
 		{
 			Name:       "component-logs",
-			Exec:       runDebugComponentLogs,
-			ShortHelp:  "enable/disable debug logs for a component",
 			ShortUsage: "tailscale debug component-logs [" + strings.Join(ipn.DebuggableComponents, "|") + "]",
+			Exec:       runDebugComponentLogs,
+			ShortHelp:  "Enable/disable debug logs for a component",
 			FlagSet: (func() *flag.FlagSet {
 				fs := newFlagSet("component-logs")
 				fs.DurationVar(&debugComponentLogsArgs.forDur, "for", time.Hour, "how long to enable debug logs for; zero or negative means to disable")
@@ -74,14 +76,16 @@ var debugCmd = &ffcli.Command{
 			})(),
 		},
 		{
-			Name:      "daemon-goroutines",
-			Exec:      runDaemonGoroutines,
-			ShortHelp: "print tailscaled's goroutines",
+			Name:       "daemon-goroutines",
+			ShortUsage: "tailscale debug daemon-goroutines",
+			Exec:       runDaemonGoroutines,
+			ShortHelp:  "Print tailscaled's goroutines",
 		},
 		{
-			Name:      "daemon-logs",
-			Exec:      runDaemonLogs,
-			ShortHelp: "watch tailscaled's server logs",
+			Name:       "daemon-logs",
+			ShortUsage: "tailscale debug daemon-logs",
+			Exec:       runDaemonLogs,
+			ShortHelp:  "Watch tailscaled's server logs",
 			FlagSet: (func() *flag.FlagSet {
 				fs := newFlagSet("daemon-logs")
 				fs.IntVar(&daemonLogsArgs.verbose, "verbose", 0, "verbosity level")
@@ -90,9 +94,10 @@ var debugCmd = &ffcli.Command{
 			})(),
 		},
 		{
-			Name:      "metrics",
-			Exec:      runDaemonMetrics,
-			ShortHelp: "print tailscaled's metrics",
+			Name:       "metrics",
+			ShortUsage: "tailscale debug metrics",
+			Exec:       runDaemonMetrics,
+			ShortHelp:  "Print tailscaled's metrics",
 			FlagSet: (func() *flag.FlagSet {
 				fs := newFlagSet("metrics")
 				fs.BoolVar(&metricsArgs.watch, "watch", false, "print JSON dump of delta values")
@@ -100,80 +105,95 @@ var debugCmd = &ffcli.Command{
 			})(),
 		},
 		{
-			Name:      "env",
-			Exec:      runEnv,
-			ShortHelp: "print cmd/tailscale environment",
+			Name:       "env",
+			ShortUsage: "tailscale debug env",
+			Exec:       runEnv,
+			ShortHelp:  "Print cmd/tailscale environment",
 		},
 		{
-			Name:      "stat",
-			Exec:      runStat,
-			ShortHelp: "stat a file",
+			Name:       "stat",
+			ShortUsage: "tailscale debug stat <files...>",
+			Exec:       runStat,
+			ShortHelp:  "Stat a file",
 		},
 		{
-			Name:      "hostinfo",
-			Exec:      runHostinfo,
-			ShortHelp: "print hostinfo",
+			Name:       "hostinfo",
+			ShortUsage: "tailscale debug hostinfo",
+			Exec:       runHostinfo,
+			ShortHelp:  "Print hostinfo",
 		},
 		{
-			Name:      "local-creds",
-			Exec:      runLocalCreds,
-			ShortHelp: "print how to access Tailscale LocalAPI",
+			Name:       "local-creds",
+			ShortUsage: "tailscale debug local-creds",
+			Exec:       runLocalCreds,
+			ShortHelp:  "Print how to access Tailscale LocalAPI",
 		},
 		{
-			Name:      "restun",
-			Exec:      localAPIAction("restun"),
-			ShortHelp: "force a magicsock restun",
+			Name:       "restun",
+			ShortUsage: "tailscale debug restun",
+			Exec:       localAPIAction("restun"),
+			ShortHelp:  "Force a magicsock restun",
 		},
 		{
-			Name:      "rebind",
-			Exec:      localAPIAction("rebind"),
-			ShortHelp: "force a magicsock rebind",
+			Name:       "rebind",
+			ShortUsage: "tailscale debug rebind",
+			Exec:       localAPIAction("rebind"),
+			ShortHelp:  "Force a magicsock rebind",
 		},
 		{
-			Name:      "derp-set-on-demand",
-			Exec:      localAPIAction("derp-set-homeless"),
-			ShortHelp: "enable DERP on-demand mode (breaks reachability)",
+			Name:       "derp-set-on-demand",
+			ShortUsage: "tailscale debug derp-set-on-demand",
+			Exec:       localAPIAction("derp-set-homeless"),
+			ShortHelp:  "Enable DERP on-demand mode (breaks reachability)",
 		},
 		{
-			Name:      "derp-unset-on-demand",
-			Exec:      localAPIAction("derp-unset-homeless"),
-			ShortHelp: "disable DERP on-demand mode",
+			Name:       "derp-unset-on-demand",
+			ShortUsage: "tailscale debug derp-unset-on-demand",
+			Exec:       localAPIAction("derp-unset-homeless"),
+			ShortHelp:  "Disable DERP on-demand mode",
 		},
 		{
-			Name:      "break-tcp-conns",
-			Exec:      localAPIAction("break-tcp-conns"),
-			ShortHelp: "break any open TCP connections from the daemon",
+			Name:       "break-tcp-conns",
+			ShortUsage: "tailscale debug break-tcp-conns",
+			Exec:       localAPIAction("break-tcp-conns"),
+			ShortHelp:  "Break any open TCP connections from the daemon",
 		},
 		{
-			Name:      "break-derp-conns",
-			Exec:      localAPIAction("break-derp-conns"),
-			ShortHelp: "break any open DERP connections from the daemon",
+			Name:       "break-derp-conns",
+			ShortUsage: "tailscale debug break-derp-conns",
+			Exec:       localAPIAction("break-derp-conns"),
+			ShortHelp:  "Break any open DERP connections from the daemon",
 		},
 		{
-			Name:      "pick-new-derp",
-			Exec:      localAPIAction("pick-new-derp"),
-			ShortHelp: "switch to some other random DERP home region for a short time",
+			Name:       "pick-new-derp",
+			ShortUsage: "tailscale debug pick-new-derp",
+			Exec:       localAPIAction("pick-new-derp"),
+			ShortHelp:  "Switch to some other random DERP home region for a short time",
 		},
 		{
-			Name:      "force-netmap-update",
-			Exec:      localAPIAction("force-netmap-update"),
-			ShortHelp: "force a full no-op netmap update (for load testing)",
+			Name:       "force-netmap-update",
+			ShortUsage: "tailscale debug force-netmap-update",
+			Exec:       localAPIAction("force-netmap-update"),
+			ShortHelp:  "Force a full no-op netmap update (for load testing)",
 		},
 		{
 			// TODO(bradfitz,maisem): eventually promote this out of debug
-			Name:      "reload-config",
-			Exec:      reloadConfig,
-			ShortHelp: "reload config",
+			Name:       "reload-config",
+			ShortUsage: "tailscale debug reload-config",
+			Exec:       reloadConfig,
+			ShortHelp:  "Reload config",
 		},
 		{
-			Name:      "control-knobs",
-			Exec:      debugControlKnobs,
-			ShortHelp: "see current control knobs",
+			Name:       "control-knobs",
+			ShortUsage: "tailscale debug control-knobs",
+			Exec:       debugControlKnobs,
+			ShortHelp:  "See current control knobs",
 		},
 		{
-			Name:      "prefs",
-			Exec:      runPrefs,
-			ShortHelp: "print prefs",
+			Name:       "prefs",
+			ShortUsage: "tailscale debug prefs",
+			Exec:       runPrefs,
+			ShortHelp:  "Print prefs",
 			FlagSet: (func() *flag.FlagSet {
 				fs := newFlagSet("prefs")
 				fs.BoolVar(&prefsArgs.pretty, "pretty", false, "If true, pretty-print output")
@@ -181,9 +201,10 @@ var debugCmd = &ffcli.Command{
 			})(),
 		},
 		{
-			Name:      "watch-ipn",
-			Exec:      runWatchIPN,
-			ShortHelp: "subscribe to IPN message bus",
+			Name:       "watch-ipn",
+			ShortUsage: "tailscale debug watch-ipn",
+			Exec:       runWatchIPN,
+			ShortHelp:  "Subscribe to IPN message bus",
 			FlagSet: (func() *flag.FlagSet {
 				fs := newFlagSet("watch-ipn")
 				fs.BoolVar(&watchIPNArgs.netmap, "netmap", true, "include netmap in messages")
@@ -194,9 +215,10 @@ var debugCmd = &ffcli.Command{
 			})(),
 		},
 		{
-			Name:      "netmap",
-			Exec:      runNetmap,
-			ShortHelp: "print the current network map",
+			Name:       "netmap",
+			ShortUsage: "tailscale debug netmap",
+			Exec:       runNetmap,
+			ShortHelp:  "Print the current network map",
 			FlagSet: (func() *flag.FlagSet {
 				fs := newFlagSet("netmap")
 				fs.BoolVar(&netmapArgs.showPrivateKey, "show-private-key", false, "include node private key in printed netmap")
@@ -204,14 +226,17 @@ var debugCmd = &ffcli.Command{
 			})(),
 		},
 		{
-			Name:      "via",
+			Name: "via",
+			ShortUsage: "tailscale via <site-id> <v4-cidr>\n" +
+				"tailscale via <v6-route>",
 			Exec:      runVia,
-			ShortHelp: "convert between site-specific IPv4 CIDRs and IPv6 'via' routes",
+			ShortHelp: "Convert between site-specific IPv4 CIDRs and IPv6 'via' routes",
 		},
 		{
-			Name:      "ts2021",
-			Exec:      runTS2021,
-			ShortHelp: "debug ts2021 protocol connectivity",
+			Name:       "ts2021",
+			ShortUsage: "tailscale debug ts2021",
+			Exec:       runTS2021,
+			ShortHelp:  "Debug ts2021 protocol connectivity",
 			FlagSet: (func() *flag.FlagSet {
 				fs := newFlagSet("ts2021")
 				fs.StringVar(&ts2021Args.host, "host", "controlplane.tailscale.com", "hostname of control plane")
@@ -221,9 +246,10 @@ var debugCmd = &ffcli.Command{
 			})(),
 		},
 		{
-			Name:      "set-expire",
-			Exec:      runSetExpire,
-			ShortHelp: "manipulate node key expiry for testing",
+			Name:       "set-expire",
+			ShortUsage: "tailscale debug set-expire --in=1m",
+			Exec:       runSetExpire,
+			ShortHelp:  "Manipulate node key expiry for testing",
 			FlagSet: (func() *flag.FlagSet {
 				fs := newFlagSet("set-expire")
 				fs.DurationVar(&setExpireArgs.in, "in", 0, "if non-zero, set node key to expire this duration from now")
@@ -231,9 +257,10 @@ var debugCmd = &ffcli.Command{
 			})(),
 		},
 		{
-			Name:      "dev-store-set",
-			Exec:      runDevStoreSet,
-			ShortHelp: "set a key/value pair during development",
+			Name:       "dev-store-set",
+			ShortUsage: "tailscale debug dev-store-set",
+			Exec:       runDevStoreSet,
+			ShortHelp:  "Set a key/value pair during development",
 			FlagSet: (func() *flag.FlagSet {
 				fs := newFlagSet("store-set")
 				fs.BoolVar(&devStoreSetArgs.danger, "danger", false, "accept danger")
@@ -241,14 +268,16 @@ var debugCmd = &ffcli.Command{
 			})(),
 		},
 		{
-			Name:      "derp",
-			Exec:      runDebugDERP,
-			ShortHelp: "test a DERP configuration",
+			Name:       "derp",
+			ShortUsage: "tailscale debug derp",
+			Exec:       runDebugDERP,
+			ShortHelp:  "Test a DERP configuration",
 		},
 		{
-			Name:      "capture",
-			Exec:      runCapture,
-			ShortHelp: "streams pcaps for debugging",
+			Name:       "capture",
+			ShortUsage: "tailscale debug capture",
+			Exec:       runCapture,
+			ShortHelp:  "Streams pcaps for debugging",
 			FlagSet: (func() *flag.FlagSet {
 				fs := newFlagSet("capture")
 				fs.StringVar(&captureArgs.outFile, "o", "", "path to stream the pcap (or - for stdout), leave empty to start wireshark")
@@ -256,9 +285,10 @@ var debugCmd = &ffcli.Command{
 			})(),
 		},
 		{
-			Name:      "portmap",
-			Exec:      debugPortmap,
-			ShortHelp: "run portmap debugging",
+			Name:       "portmap",
+			ShortUsage: "tailscale debug portmap",
+			Exec:       debugPortmap,
+			ShortHelp:  "Run portmap debugging",
 			FlagSet: (func() *flag.FlagSet {
 				fs := newFlagSet("portmap")
 				fs.DurationVar(&debugPortmapArgs.duration, "duration", 5*time.Second, "timeout for port mapping")
@@ -270,14 +300,16 @@ var debugCmd = &ffcli.Command{
 			})(),
 		},
 		{
-			Name:      "peer-endpoint-changes",
-			Exec:      runPeerEndpointChanges,
-			ShortHelp: "prints debug information about a peer's endpoint changes",
+			Name:       "peer-endpoint-changes",
+			ShortUsage: "tailscale debug peer-endpoint-changes <hostname-or-IP>",
+			Exec:       runPeerEndpointChanges,
+			ShortHelp:  "Prints debug information about a peer's endpoint changes",
 		},
 		{
-			Name:      "dial-types",
-			Exec:      runDebugDialTypes,
-			ShortHelp: "prints debug information about connecting to a given host or IP",
+			Name:       "dial-types",
+			ShortUsage: "tailscale debug dial-types <hostname-or-IP> <port>",
+			Exec:       runDebugDialTypes,
+			ShortHelp:  "Prints debug information about connecting to a given host or IP",
 			FlagSet: (func() *flag.FlagSet {
 				fs := newFlagSet("dial-types")
 				fs.StringVar(&debugDialTypesArgs.network, "network", "tcp", `network type to dial ("tcp", "udp", etc.)`)
@@ -867,7 +899,7 @@ var setExpireArgs struct {
 
 func runSetExpire(ctx context.Context, args []string) error {
 	if len(args) != 0 || setExpireArgs.in == 0 {
-		return errors.New("usage --in=<duration>")
+		return errors.New("usage: tailscale debug set-expire --in=<duration>")
 	}
 	return localClient.DebugSetExpireIn(ctx, setExpireArgs.in)
 }
@@ -966,7 +998,7 @@ func runPeerEndpointChanges(ctx context.Context, args []string) error {
 	}
 
 	if len(args) != 1 || args[0] == "" {
-		return errors.New("usage: peer-status <hostname-or-IP>")
+		return errors.New("usage: tailscale debug peer-endpoint-changes <hostname-or-IP>")
 	}
 	var ip string
 
@@ -1042,7 +1074,7 @@ func runDebugDialTypes(ctx context.Context, args []string) error {
 	}
 
 	if len(args) != 2 || args[0] == "" || args[1] == "" {
-		return errors.New("usage: dial-types <hostname-or-IP> <port>")
+		return errors.New("usage: tailscale debug dial-types <hostname-or-IP> <port>")
 	}
 
 	port, err := strconv.ParseUint(args[1], 10, 16)