Checkout a specific git commit

README.md

@@ -150,7 +150,7 @@ When running kaniko, use the `--context` flag with the appropriate prefix to spe
 | GCS Bucket        | gs://[bucket name]/[path to .tar.gz]                            | `gs://kaniko-bucket/path/to/context.tar.gz`                   |
 | S3 Bucket         | s3://[bucket name]/[path to .tar.gz]                            | `s3://kaniko-bucket/path/to/context.tar.gz`                   |
 | Azure Blob Storage| https://[account].[azureblobhostsuffix]/[container]/[path to .tar.gz] | `https://myaccount.blob.core.windows.net/container/path/to/context.tar.gz` |
-| Git Repository    | git://[repository url][#reference]                              | `git://github.com/acme/myproject.git#refs/heads/mybranch`     |
+| Git Repository    | git://[repository url][#reference][#commit-id]                              | `git://github.com/acme/myproject.git#refs/heads/mybranch#<desired-commit-id>`     |
 
 If you don't specify a prefix, kaniko will assume a local directory.
 For example, to use a GCS bucket called `kaniko-bucket`, you would pass in `--context=gs://kaniko-bucket/path/to/context.tar.gz`.

pkg/buildcontext/git.go

@@ -41,6 +41,28 @@ func (g *Git) UnpackTarFromBuildContext() (string, error) {
 	if len(parts) > 1 {
 		options.ReferenceName = plumbing.ReferenceName(parts[1])
 	}
-	_, err := git.PlainClone(directory, false, &options)
+	r, err := git.PlainClone(directory, false, &options)
+
+	if err == nil && len(parts) > 2 {
+		// ... retrieving the commit being pointed by HEAD
+		_, err := r.Head()
+		if err != nil {
+			return directory, err
+		}
+
+		w, err := r.Worktree()
+		if err != nil {
+			return directory, err
+		}
+
+		// ... checking out to desired commit
+		err = w.Checkout(&git.CheckoutOptions{
+			Hash: plumbing.NewHash(parts[2]),
+		})
+		if err != nil {
+			return directory, err
+		}
+	}
+
 	return directory, err
 }