feat: new git flags

Signed-off-by: Carlos Alexandro Becker <caarlos0@gmail.com>

cmd/executor/cmd/root.go

@@ -175,6 +175,9 @@ func addKanikoOptionsFlags() {
 	RootCmd.PersistentFlags().VarP(&opts.Labels, "label", "", "Set metadata for an image. Set it repeatedly for multiple labels.")
 	RootCmd.PersistentFlags().BoolVarP(&opts.SkipUnusedStages, "skip-unused-stages", "", false, "Build only used stages if defined to true. Otherwise it builds by default all stages, even the unnecessaries ones until it reaches the target stage / end of Dockerfile")
 	RootCmd.PersistentFlags().BoolVarP(&opts.RunV2, "use-new-run", "", false, "Experimental run command to detect file system changes. This new run command does no rely on snapshotting to detect changes.")
+	RootCmd.PersistentFlags().StringVarP(&opts.Git.Branch, "git-branch", "", "", "Branch to clone if build context is a git repository")
+	RootCmd.PersistentFlags().BoolVarP(&opts.Git.SingleBranch, "git-single-branch", "", false, "Whether to clone a single branch")
+	RootCmd.PersistentFlags().BoolVarP(&opts.Git.RecurseSubmodules, "git-recurse-submodules", "", false, "Whether to clone recursing submodules")
 }
 
 // addHiddenFlags marks certain flags as hidden from the executor help text
@@ -266,7 +269,11 @@ func resolveSourceContext() error {
 			opts.SrcContext = opts.Bucket
 		}
 	}
-	contextExecutor, err := buildcontext.GetBuildContext(opts.SrcContext)
+	contextExecutor, err := buildcontext.GetBuildContext(opts.SrcContext, buildcontext.BuildOptions{
+		GitBranch:            opts.Git.Branch,
+		GitSingleBranch:      opts.Git.SingleBranch,
+		GitRecurseSubmodules: opts.Git.RecurseSubmodules,
+	})
 	if err != nil {
 		return err
 	}

pkg/buildcontext/buildcontext.go

@@ -28,6 +28,12 @@ const (
 	TarBuildContextPrefix = "tar://"
 )
 
+type BuildOptions struct {
+	GitBranch            string
+	GitSingleBranch      bool
+	GitRecurseSubmodules bool
+}
+
 // BuildContext unifies calls to download and unpack the build context.
 type BuildContext interface {
 	// Unpacks a build context and returns the directory where it resides
@@ -36,7 +42,7 @@ type BuildContext interface {
 
 // GetBuildContext parses srcContext for the prefix and returns related buildcontext
 // parser
-func GetBuildContext(srcContext string) (BuildContext, error) {
+func GetBuildContext(srcContext string, opts BuildOptions) (BuildContext, error) {
 	split := strings.SplitAfter(srcContext, "://")
 	if len(split) > 1 {
 		prefix := split[0]
@@ -50,7 +56,7 @@ func GetBuildContext(srcContext string) (BuildContext, error) {
 		case constants.LocalDirBuildContextPrefix:
 			return &Dir{context: context}, nil
 		case constants.GitBuildContextPrefix:
-			return &Git{context: context}, nil
+			return &Git{context: context, opts: opts}, nil
 		case constants.HTTPSBuildContextPrefix:
 			if util.ValidAzureBlobStorageHost(srcContext) {
 				return &AzureBlob{context: srcContext}, nil

pkg/buildcontext/git.go

@@ -17,14 +17,20 @@ limitations under the License.
 package buildcontext
 
 import (
+	"fmt"
 	"os"
 	"strings"
 
 	"github.com/GoogleContainerTools/kaniko/pkg/constants"
+	"github.com/go-git/go-billy/v5/osfs"
 	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/config"
 	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/cache"
 	"github.com/go-git/go-git/v5/plumbing/transport"
 	"github.com/go-git/go-git/v5/plumbing/transport/http"
+	"github.com/go-git/go-git/v5/storage/filesystem"
+	"github.com/sirupsen/logrus"
 )
 
 const (
@@ -43,24 +49,83 @@ var (
 // Git unifies calls to download and unpack the build context.
 type Git struct {
 	context string
+	opts    BuildOptions
 }
 
 // UnpackTarFromBuildContext will provide the directory where Git Repository is Cloned
 func (g *Git) UnpackTarFromBuildContext() (string, error) {
 	directory := constants.BuildContextDir
 	parts := strings.Split(g.context, "#")
+	url := getGitPullMethod() + "://" + parts[0]
 	options := git.CloneOptions{
-		URL:      getGitPullMethod() + "://" + parts[0],
-		Auth:     getGitAuth(),
-		Progress: os.Stdout,
+		URL:               url,
+		Auth:              getGitAuth(),
+		Progress:          os.Stdout,
+		SingleBranch:      g.opts.GitSingleBranch,
+		RecurseSubmodules: getRecurseSubmodules(g.opts.GitRecurseSubmodules),
 	}
 	if len(parts) > 1 {
 		options.ReferenceName = plumbing.ReferenceName(parts[1])
 	}
+
+	if branch := g.opts.GitBranch; branch != "" {
+		ref, err := getGitReferenceName(directory, url, branch)
+		if err != nil {
+			return directory, err
+		}
+		options.ReferenceName = ref
+	}
+
+	logrus.Debugf("Getting source from reference %s", options.ReferenceName)
 	_, err := git.PlainClone(directory, false, &options)
 	return directory, err
 }
 
+func getGitReferenceName(directory string, url string, branch string) (plumbing.ReferenceName, error) {
+	var remote = git.NewRemote(
+		filesystem.NewStorage(
+			osfs.New(directory),
+			cache.NewObjectLRUDefault(),
+		),
+		&config.RemoteConfig{
+			URLs: []string{url},
+		},
+	)
+
+	refs, err := remote.List(&git.ListOptions{
+		Auth: getGitAuth(),
+	})
+	if err != nil {
+		return plumbing.HEAD, err
+	}
+
+	if ref := plumbing.NewBranchReferenceName(branch); gitRefExists(ref, refs) {
+		return ref, nil
+	}
+
+	if ref := plumbing.NewTagReferenceName(branch); gitRefExists(ref, refs) {
+		return ref, nil
+	}
+
+	return plumbing.HEAD, fmt.Errorf("invalid branch: %s", branch)
+}
+
+func gitRefExists(ref plumbing.ReferenceName, refs []*plumbing.Reference) bool {
+	for _, ref2 := range refs {
+		if ref.String() == ref2.Name().String() {
+			return true
+		}
+	}
+	return false
+}
+
+func getRecurseSubmodules(v bool) git.SubmoduleRescursivity {
+	if v {
+		return git.DefaultSubmoduleRecursionDepth
+	}
+	return git.NoRecurseSubmodules
+}
+
 func getGitAuth() transport.AuthMethod {
 	username := os.Getenv(gitAuthUsernameEnvKey)
 	password := os.Getenv(gitAuthPasswordEnvKey)

pkg/config/options.go

@@ -58,6 +58,13 @@ type KanikoOptions struct {
 	IgnoreVarRun            bool
 	SkipUnusedStages        bool
 	RunV2                   bool
+	Git                     KanikoGitOptions
+}
+
+type KanikoGitOptions struct {
+	Branch            string
+	SingleBranch      bool
+	RecurseSubmodules bool
 }
 
 // WarmerOptions are options that are set by command line arguments to the cache warmer.