Merge pull request #1071 from sparr/path_constants

Add constants for "index.json" and "blobs" alongside "oci-layout" as parts of the layout specification

specs-go/v1/layout.go

@@ -15,10 +15,14 @@
 package v1
 
 const (
-	// ImageLayoutFile is the file name of oci image layout file
+	// ImageLayoutFile is the file name containing ImageLayout in an OCI Image Layout
 	ImageLayoutFile = "oci-layout"
 	// ImageLayoutVersion is the version of ImageLayout
 	ImageLayoutVersion = "1.0.0"
+	// ImageIndexFile is the file name of the entry point for references and descriptors in an OCI Image Layout
+	ImageIndexFile = "index.json"
+	// ImageBlobsDir is the directory name containing content addressable blobs in an OCI Image Layout
+	ImageBlobsDir = "blobs"
 )
 
 // ImageLayout is the structure in the "oci-layout" file, found in the root