diff --git a/metropolis/test/localregistry/spec/BUILD.bazel b/metropolis/test/localregistry/spec/BUILD.bazel
new file mode 100644
index 0000000..71253d1
--- /dev/null
+++ b/metropolis/test/localregistry/spec/BUILD.bazel
@@ -0,0 +1,23 @@
+load("@rules_proto//proto:defs.bzl", "proto_library")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
+
+proto_library(
+    name = "spec_proto",
+    srcs = ["manifest.proto"],
+    visibility = ["//visibility:public"],
+)
+
+go_proto_library(
+    name = "spec_go_proto",
+    importpath = "source.monogon.dev/metropolis/test/localregistry/spec",
+    proto = ":spec_proto",
+    visibility = ["//visibility:public"],
+)
+
+go_library(
+    name = "spec",
+    embed = [":spec_go_proto"],
+    importpath = "source.monogon.dev/metropolis/test/localregistry/spec",
+    visibility = ["//visibility:public"],
+)
diff --git a/metropolis/test/localregistry/spec/gomod-generated-placeholder.go b/metropolis/test/localregistry/spec/gomod-generated-placeholder.go
new file mode 100644
index 0000000..f09cd57
--- /dev/null
+++ b/metropolis/test/localregistry/spec/gomod-generated-placeholder.go
@@ -0,0 +1 @@
+package spec
diff --git a/metropolis/test/localregistry/spec/manifest.proto b/metropolis/test/localregistry/spec/manifest.proto
new file mode 100644
index 0000000..bb53581
--- /dev/null
+++ b/metropolis/test/localregistry/spec/manifest.proto
@@ -0,0 +1,19 @@
+syntax = "proto3";
+
+package monogon.metropolis.pkg.localregistry;
+
+option go_package = "source.monogon.dev/metropolis/test/localregistry/spec";
+
+// Single image metadata
+message Image {
+    // Name of the image (no domain or tag, just slash-separated path)
+    string name = 1;
+    // Path to the image
+    string path = 2;
+}
+
+// Main message
+message Manifest {
+    // List of images for the local registry
+    repeated Image images = 1;
+}
\ No newline at end of file