osbase/build/mkoci: add package

This adds the mkoci package, which contains a Bazel rule for building OS
image OCI artifacts.

Change-Id: I1a234238c4982078db8ecea684e5491c980b97c3
Reviewed-on: https://review.monogon.dev/c/monogon/+/4088
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
Tested-by: Jenkins CI
diff --git a/osbase/build/mkoci/BUILD.bazel b/osbase/build/mkoci/BUILD.bazel
new file mode 100644
index 0000000..9832f4c
--- /dev/null
+++ b/osbase/build/mkoci/BUILD.bazel
@@ -0,0 +1,21 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
+
+go_library(
+    name = "mkoci_lib",
+    srcs = ["main.go"],
+    importpath = "source.monogon.dev/osbase/build/mkoci",
+    visibility = ["//visibility:private"],
+    deps = [
+        "//osbase/oci/osimage",
+        "@com_github_klauspost_compress//zstd",
+        "@com_github_opencontainers_go_digest//:go-digest",
+        "@com_github_opencontainers_image_spec//specs-go",
+        "@com_github_opencontainers_image_spec//specs-go/v1:specs-go",
+    ],
+)
+
+go_binary(
+    name = "mkoci",
+    embed = [":mkoci_lib"],
+    visibility = ["//visibility:public"],
+)