go.mod: upgrade nfpm to v2 (#8786)

Upgrade the nfpm package to the latest version to pick up
https://github.com/goreleaser/nfpm/commit/24a43c5ad7cfc549e8a4ec930521a97a30f26cc8.
The upgrade is from v0 to v2, so there was some breakage to fix.
Generated packages should have the same contents as before.

Updates https://github.com/tailscale/tailscale/issues/1882

Signed-off-by: Andrew Lytvynov <awly@tailscale.com>

cmd/mkpkg/main.go

@@ -11,35 +11,40 @@ import (
 	"os"
 	"strings"
 
-	"github.com/goreleaser/nfpm"
-	_ "github.com/goreleaser/nfpm/deb"
-	_ "github.com/goreleaser/nfpm/rpm"
+	"github.com/goreleaser/nfpm/v2"
+	_ "github.com/goreleaser/nfpm/v2/deb"
+	"github.com/goreleaser/nfpm/v2/files"
+	_ "github.com/goreleaser/nfpm/v2/rpm"
 )
 
 // parseFiles parses a comma-separated list of colon-separated pairs
-// into a map of filePathOnDisk -> filePathInPackage.
-func parseFiles(s string) (map[string]string, error) {
-	ret := map[string]string{}
+// into files.Contents format.
+func parseFiles(s string, typ string) (files.Contents, error) {
 	if len(s) == 0 {
-		return ret, nil
+		return nil, nil
 	}
+	var contents files.Contents
 	for _, f := range strings.Split(s, ",") {
 		fs := strings.Split(f, ":")
 		if len(fs) != 2 {
 			return nil, fmt.Errorf("unparseable file field %q", f)
 		}
-		ret[fs[0]] = fs[1]
+		contents = append(contents, &files.Content{Type: files.TypeFile, Source: fs[0], Destination: fs[1]})
 	}
-	return ret, nil
+	return contents, nil
 }
 
-func parseEmptyDirs(s string) []string {
+func parseEmptyDirs(s string) files.Contents {
 	// strings.Split("", ",") would return []string{""}, which is not suitable:
 	// this would create an empty dir record with path "", breaking the package
 	if s == "" {
 		return nil
 	}
-	return strings.Split(s, ",")
+	var contents files.Contents
+	for _, d := range strings.Split(s, ",") {
+		contents = append(contents, &files.Content{Type: files.TypeDir, Destination: d})
+	}
+	return contents
 }
 
 func main() {
@@ -48,7 +53,7 @@ func main() {
 	description := flag.String("description", "The easiest, most secure, cross platform way to use WireGuard + oauth2 + 2FA/SSO", "package description")
 	goarch := flag.String("arch", "amd64", "GOARCH this package is for")
 	pkgType := flag.String("type", "deb", "type of package to build (deb or rpm)")
-	files := flag.String("files", "", "comma-separated list of files in src:dst form")
+	regularFiles := flag.String("files", "", "comma-separated list of files in src:dst form")
 	configFiles := flag.String("configs", "", "like --files, but for files marked as user-editable config files")
 	emptyDirs := flag.String("emptydirs", "", "comma-separated list of empty directories")
 	version := flag.String("version", "0.0.0", "version of the package")
@@ -60,15 +65,20 @@ func main() {
 	recommends := flag.String("recommends", "", "comma-separated list of packages this package recommends")
 	flag.Parse()
 
-	filesMap, err := parseFiles(*files)
+	filesList, err := parseFiles(*regularFiles, files.TypeFile)
 	if err != nil {
 		log.Fatalf("Parsing --files: %v", err)
 	}
-	configsMap, err := parseFiles(*configFiles)
+	configsList, err := parseFiles(*configFiles, files.TypeConfig)
 	if err != nil {
 		log.Fatalf("Parsing --configs: %v", err)
 	}
 	emptyDirList := parseEmptyDirs(*emptyDirs)
+	contents := append(filesList, append(configsList, emptyDirList...)...)
+	contents, err = files.PrepareForPackager(contents, 0, *pkgType, false)
+	if err != nil {
+		log.Fatalf("Building package contents: %v", err)
+	}
 	info := nfpm.WithDefaults(&nfpm.Info{
 		Name:        *name,
 		Arch:        *goarch,
@@ -79,9 +89,7 @@ func main() {
 		Homepage:    "https://www.tailscale.com",
 		License:     "MIT",
 		Overridables: nfpm.Overridables{
-			EmptyFolders: emptyDirList,
-			Files:        filesMap,
-			ConfigFiles:  configsMap,
+			Contents: contents,
 			Scripts: nfpm.Scripts{
 				PostInstall: *postinst,
 				PreRemove:   *prerm,