treewide: replace rules_docker with rules_oci

rules_docker is not maintained anymore and recommends migration to
rules_oci

Change-Id: I089f3cf44888b3c3c0baa2c84a319b04b1a7dec4
Reviewed-on: https://review.monogon.dev/c/monogon/+/2712
Tested-by: Jenkins CI
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/metropolis/pkg/localregistry/spec/manifest.proto b/metropolis/pkg/localregistry/spec/manifest.proto
index b4daeab..b28c8b7 100644
--- a/metropolis/pkg/localregistry/spec/manifest.proto
+++ b/metropolis/pkg/localregistry/spec/manifest.proto
@@ -4,23 +4,12 @@
 
 option go_package = "source.monogon.dev/metropolis/pkg/localregistry/spec";
 
-// BlobDescriptor is metadata for a single registry blob. Analogous to a
-// distribution.Descriptor in Go.
-message BlobDescriptor {
-    // Path to the file in the build directory.
-    string file_path = 1;
-    // Path to a file containing the SHA256 digest of the blob.
-    string digest_path = 2;
-}
-
 // Single image metadata
 message Image {
     // Name of the image (no domain or tag, just slash-separated path)
     string name = 1;
-    // Config blob
-    BlobDescriptor config = 2;
-    // Layer blobs in order
-    repeated BlobDescriptor layers = 3;
+    // Path to the image
+    string path = 2;
 }
 
 // Main message