cmd/tailscale/cli,client,ipn: add appc-routes cli command

Allow the user to access information about routes an app connector has
learned, such as how many routes for each domain.

Fixes tailscale/corp#32624

Signed-off-by: Fran Bull <fran@tailscale.com>

cmd/tailscale/cli/appcroutes.go

@@ -0,0 +1,153 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package cli
+
+import (
+	"context"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"slices"
+	"strings"
+
+	"github.com/peterbourgon/ff/v3/ffcli"
+	"tailscale.com/appc"
+)
+
+var appcRoutesArgs struct {
+	all       bool
+	domainMap bool
+	n         bool
+}
+
+var appcRoutesCmd = &ffcli.Command{
+	Name:       "appc-routes",
+	ShortUsage: "tailscale appc-routes",
+	Exec:       runAppcRoutesInfo,
+	ShortHelp:  "Print the current app connector routes",
+	FlagSet: (func() *flag.FlagSet {
+		fs := newFlagSet("appc-routes")
+		fs.BoolVar(&appcRoutesArgs.all, "all", false, "Print learned domains and routes and extra policy configured routes.")
+		fs.BoolVar(&appcRoutesArgs.domainMap, "map", false, "Print the map of learned domains: [routes].")
+		fs.BoolVar(&appcRoutesArgs.n, "n", false, "Print the total number of routes this node advertises.")
+		return fs
+	})(),
+	LongHelp: strings.TrimSpace(`
+The 'tailscale appc-routes' command prints the current App Connector route status.
+
+By default this command prints the domains configured in the app connector configuration and how many routes have been
+learned for each domain.
+
+--all prints the routes learned from the domains configured in the app connector configuration; and any extra routes provided
+in the the policy app connector 'routes' field.
+
+--map prints the routes learned from the domains configured in the app connector configuration.
+
+-n prints the total number of routes advertised by this device, whether learned, set in the policy, or set locally.
+
+For more information about App Connectors, refer to
+https://tailscale.com/kb/1281/app-connectors
+`),
+}
+
+func getAllOutput(ri *appc.RouteInfo) (string, error) {
+	domains, err := json.MarshalIndent(ri.Domains, " ", "  ")
+	if err != nil {
+		return "", err
+	}
+	control, err := json.MarshalIndent(ri.Control, " ", "  ")
+	if err != nil {
+		return "", err
+	}
+	s := fmt.Sprintf(`Learned Routes
+==============
+%s
+
+Routes from Policy
+==================
+%s
+`, domains, control)
+	return s, nil
+}
+
+type domainCount struct {
+	domain string
+	count  int
+}
+
+func getSummarizeLearnedOutput(ri *appc.RouteInfo) string {
+	x := make([]domainCount, len(ri.Domains))
+	i := 0
+	maxDomainWidth := 0
+	for k, v := range ri.Domains {
+		if len(k) > maxDomainWidth {
+			maxDomainWidth = len(k)
+		}
+		x[i] = domainCount{domain: k, count: len(v)}
+		i++
+	}
+	slices.SortFunc(x, func(i, j domainCount) int {
+		if i.count > j.count {
+			return -1
+		}
+		if i.count < j.count {
+			return 1
+		}
+		if i.domain > j.domain {
+			return 1
+		}
+		if i.domain < j.domain {
+			return -1
+		}
+		return 0
+	})
+	s := ""
+	fmtString := fmt.Sprintf("%%-%ds %%d\n", maxDomainWidth) // eg "%-10s %d\n"
+	for _, dc := range x {
+		s += fmt.Sprintf(fmtString, dc.domain, dc.count)
+	}
+	return s
+}
+
+func runAppcRoutesInfo(ctx context.Context, args []string) error {
+	prefs, err := localClient.GetPrefs(ctx)
+	if err != nil {
+		return err
+	}
+	if !prefs.AppConnector.Advertise {
+		fmt.Println("not a connector")
+		return nil
+	}
+
+	if appcRoutesArgs.n {
+		fmt.Println(len(prefs.AdvertiseRoutes))
+		return nil
+	}
+
+	routeInfo, err := localClient.GetAppConnectorRouteInfo(ctx)
+	if err != nil {
+		return err
+	}
+
+	if appcRoutesArgs.domainMap {
+		domains, err := json.Marshal(routeInfo.Domains)
+		if err != nil {
+			return err
+		}
+		fmt.Println(string(domains))
+		return nil
+	}
+
+	if appcRoutesArgs.all {
+		s, err := getAllOutput(&routeInfo)
+		if err != nil {
+			return err
+		}
+		fmt.Println(s)
+		return nil
+	}
+
+	fmt.Print(getSummarizeLearnedOutput(&routeInfo))
+	return nil
+}

cmd/tailscale/cli/cli.go

@@ -276,6 +276,7 @@ change in the future.
 			idTokenCmd,
 			configureHostCmd(),
 			systrayCmd,
+			appcRoutesCmd,
 		),
 		FlagSet: rootfs,
 		Exec: func(ctx context.Context, args []string) error {

cmd/tailscale/depaware.txt

@@ -70,6 +70,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         software.sslmate.com/src/go-pkcs12                           from tailscale.com/cmd/tailscale/cli
         software.sslmate.com/src/go-pkcs12/internal/rc2              from software.sslmate.com/src/go-pkcs12
         tailscale.com                                                from tailscale.com/version
+        tailscale.com/appc                                           from tailscale.com/client/local+
      💣 tailscale.com/atomicfile                                     from tailscale.com/cmd/tailscale/cli+
         tailscale.com/client/local                                   from tailscale.com/client/tailscale+
    L    tailscale.com/client/systray                                 from tailscale.com/cmd/tailscale/cli
@@ -168,6 +169,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
    L 💣 tailscale.com/util/dirwalk                                   from tailscale.com/metrics
         tailscale.com/util/dnsname                                   from tailscale.com/cmd/tailscale/cli+
         tailscale.com/util/eventbus                                  from tailscale.com/client/local+
+        tailscale.com/util/execqueue                                 from tailscale.com/appc
         tailscale.com/util/groupmember                               from tailscale.com/client/web
      💣 tailscale.com/util/hashx                                     from tailscale.com/util/deephash
         tailscale.com/util/httpm                                     from tailscale.com/client/tailscale+