cmd/gomote: add support for groups to the rm command

For golang/go#53956.

Change-Id: I1224aabae4e80cb0380baaa0d5d7c434c59af61a
Reviewed-on: https://go-review.googlesource.com/c/build/+/418937
Reviewed-by: Carlos Amedee <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Run-TryBot: Michael Knyszek <[email protected]>
Auto-Submit: Michael Knyszek <[email protected]>

cmd/gomote/rm.go

@@ -11,6 +11,7 @@ import (
 	"os"
 
 	"golang.org/x/build/internal/gomote/protos"
+	"golang.org/x/sync/errgroup"
 )
 
 func legacyRm(args []string) error {
@@ -41,29 +42,61 @@ func legacyRm(args []string) error {
 }
 
 func rm(args []string) error {
-	if activeGroup != nil {
-		return fmt.Errorf("command does not yet support groups")
-	}
-
 	fs := flag.NewFlagSet("rm", flag.ContinueOnError)
 	fs.Usage = func() {
-		fmt.Fprintln(os.Stderr, "rm usage: gomote rm <instance> <file-or-dir>+")
-		fmt.Fprintln(os.Stderr, "          gomote rm <instance> .  (to delete everything)")
+		fmt.Fprintln(os.Stderr, "rm usage: gomote rm [instance] <file-or-dir>+")
+		fmt.Fprintln(os.Stderr, "          gomote rm [instance] .  (to delete everything)")
+		fmt.Fprintln(os.Stderr)
+		fmt.Fprintln(os.Stderr, "Instance name is optional if a group is specified.")
 		fs.PrintDefaults()
 		os.Exit(1)
 	}
 	fs.Parse(args)
 
-	if fs.NArg() < 2 {
-		fs.Usage()
-	}
-	name := fs.Arg(0)
-	args = fs.Args()[1:]
 	ctx := context.Background()
+	var rmSet []string
+	var paths []string
+	if err := doPing(ctx, fs.Arg(0)); instanceDoesNotExist(err) {
+		// When there's no active group, this is just an error.
+		if activeGroup == nil {
+			return fmt.Errorf("instance %q: %s", fs.Arg(0), statusFromError(err))
+		}
+		// When there is an active group, this just means that we're going
+		// to use the group instead and assume the rest is a command.
+		for _, inst := range activeGroup.Instances {
+			rmSet = append(rmSet, inst)
+		}
+		if fs.NArg() == 0 {
+			fmt.Fprintln(os.Stderr, "error: not enough arguments")
+			fs.Usage()
+		}
+		paths = fs.Args()
+	} else if err == nil {
+		rmSet = append(rmSet, fs.Arg(0))
+		if fs.NArg() == 1 {
+			fmt.Fprintln(os.Stderr, "error: not enough arguments")
+			fs.Usage()
+		}
+		paths = fs.Args()[1:]
+	} else {
+		return fmt.Errorf("checking instance %q: %v", fs.Arg(0), err)
+	}
+
+	eg, ctx := errgroup.WithContext(context.Background())
+	for _, inst := range rmSet {
+		inst := inst
+		eg.Go(func() error {
+			return doRm(ctx, inst, paths)
+		})
+	}
+	return eg.Wait()
+}
+
+func doRm(ctx context.Context, inst string, paths []string) error {
 	client := gomoteServerClient(ctx)
 	if _, err := client.RemoveFiles(ctx, &protos.RemoveFilesRequest{
-		GomoteId: name,
-		Paths:    args,
+		GomoteId: inst,
+		Paths:    paths,
 	}); err != nil {
 		return fmt.Errorf("unable to remove files: %s", statusFromError(err))
 	}