Support tar files for multi-arch images

Fixes #112
bazel-contrib · Aug 8, 2023 · 573376c · 573376c
1 parent 0f7297c
commit 573376c
Showing 1 changed file with 70 additions and 18 deletions.
diff --git a/oci/private/tarball.sh.tpl b/oci/private/tarball.sh.tpl
@@ -5,36 +5,88 @@ readonly STAGING_DIR=$(mktemp -d)
 readonly YQ="{{yq}}"
 readonly IMAGE_DIR="{{image_dir}}"
 readonly BLOBS_DIR="${STAGING_DIR}/blobs"
-readonly TARBALL_PATH="{{tarball_path}}"
+readonly TARBALL_PATH="$(pwd)/{{tarball_path}}"
 readonly TAGS_FILE="{{tags}}"
+readonly INDEX_FILE="${IMAGE_DIR}/index.json"
+
+cp_f_with_mkdir() {
+  SRC="$1"
+  DST="$2"
+  mkdir -p "$(dirname "${DST}")"
+  cp -f "${SRC}" "${DST}"
+}
 
 # Replace newlines (unix or windows line endings) with % character.
 # We can't pass newlines to yq due to https://github.com/mikefarah/yq/issues/1430 and 
 # we can't update YQ at the moment because structure_test depends on a specific version:
 # see https://github.com/bazel-contrib/rules_oci/issues/212 
 REPOTAGS="$(tr -d '\r' < "${TAGS_FILE}" | tr '\n' '%')"
 
-MANIFEST_DIGEST=$(${YQ} eval '.manifests[0].digest | sub(":"; "/")' "${IMAGE_DIR}/index.json" | tr  -d '"')
-MANIFEST_BLOB_PATH="${IMAGE_DIR}/blobs/${MANIFEST_DIGEST}"
+MANIFESTS_LENGTH=$("${YQ}" eval '.manifests | length' "${INDEX_FILE}")
+if [[ "${MANIFESTS_LENGTH}" != 1 ]]; then
+  echo >&2 "Expected exactly one manifest in ${INDEX_FILE}"
+  exit 1
+fi
+
+MEDIA_TYPE=$("${YQ}" eval ".manifests[0].mediaType" "${INDEX_FILE}")
+if [[ "${MEDIA_TYPE}" == "application/vnd.oci.image.index.v1+json" ]]; then
+  # Handle multi-architecture image indexes.
+  # Ideally the toolchains we rely on would output these for us, but they don't seem to.
+
+  if [[ -n "${REPOTAGS}" ]]; then
+    echo >&2 "OCI image indexes don't support setting repo tags"
+    echo >&2 "Repo tags can only be set for single-architecture docker-packed images"
+    exit 1
+  fi
+
+  cp "${IMAGE_DIR}/index.json" "${STAGING_DIR}/index.json"
+  echo -n '{"imageLayoutVersion": "1.0.0"}' > "${STAGING_DIR}/oci-layout"
+
+  INDEX_FILE_MANIFEST_DIGEST=$("${YQ}" eval '.manifests[0].digest | sub(":"; "/")' "${INDEX_FILE}" | tr  -d '"')
+  INDEX_FILE_MANIFEST_BLOB_PATH="${IMAGE_DIR}/blobs/${INDEX_FILE_MANIFEST_DIGEST}"
+
+  cp_f_with_mkdir "${INDEX_FILE_MANIFEST_BLOB_PATH}" "${BLOBS_DIR}/${INDEX_FILE_MANIFEST_DIGEST}"
+
+  IMAGE_MANIFESTS_DIGESTS=($("${YQ}" '.manifests[] | .digest | sub(":"; "/")' "${INDEX_FILE_MANIFEST_BLOB_PATH}"))
+
+  for IMAGE_MANIFEST_DIGEST in "${IMAGE_MANIFESTS_DIGESTS[@]}"; do
+    IMAGE_MANIFEST_BLOB_PATH="${IMAGE_DIR}/blobs/${IMAGE_MANIFEST_DIGEST}"
+    cp_f_with_mkdir "${IMAGE_MANIFEST_BLOB_PATH}" "${BLOBS_DIR}/${IMAGE_MANIFEST_DIGEST}"
+
+    CONFIG_DIGEST=$("${YQ}" eval '.config.digest  | sub(":"; "/")' ${IMAGE_MANIFEST_BLOB_PATH})
+    CONFIG_BLOB_PATH="${IMAGE_DIR}/blobs/${CONFIG_DIGEST}"
+    cp_f_with_mkdir "${CONFIG_BLOB_PATH}" "${BLOBS_DIR}/${CONFIG_DIGEST}"
+
+    LAYER_DIGESTS=$("${YQ}" eval '.layers | map(.digest | sub(":"; "/"))' "${IMAGE_MANIFEST_BLOB_PATH}")
+    for LAYER_DIGEST in $("${YQ}" ".[]" <<< $LAYER_DIGESTS); do
+      cp_f_with_mkdir "${IMAGE_DIR}/blobs/${LAYER_DIGEST}" ${BLOBS_DIR}/${LAYER_DIGEST}
+    done
+  done
+else
+  # Assume we're dealing with a single application/vnd.docker.distribution.manifest.list.v2+json manifest.
+
+  MANIFEST_DIGEST=$(${YQ} eval '.manifests[0].digest | sub(":"; "/")' "${INDEX_FILE}" | tr  -d '"')
+  MANIFEST_BLOB_PATH="${IMAGE_DIR}/blobs/${MANIFEST_DIGEST}"
 
-CONFIG_DIGEST=$(${YQ} eval '.config.digest  | sub(":"; "/")' ${MANIFEST_BLOB_PATH})
-CONFIG_BLOB_PATH="${IMAGE_DIR}/blobs/${CONFIG_DIGEST}"
+  CONFIG_DIGEST=$(${YQ} eval '.config.digest  | sub(":"; "/")' ${MANIFEST_BLOB_PATH})
+  CONFIG_BLOB_PATH="${IMAGE_DIR}/blobs/${CONFIG_DIGEST}"
 
-LAYERS=$(${YQ} eval '.layers | map(.digest | sub(":"; "/"))' ${MANIFEST_BLOB_PATH})
+  LAYERS=$(${YQ} eval '.layers | map(.digest | sub(":"; "/"))' ${MANIFEST_BLOB_PATH})
 
-mkdir -p $(dirname "${BLOBS_DIR}/${CONFIG_DIGEST}")
-cp "${CONFIG_BLOB_PATH}" "${BLOBS_DIR}/${CONFIG_DIGEST}"
+  cp_f_with_mkdir "${CONFIG_BLOB_PATH}" "${BLOBS_DIR}/${CONFIG_DIGEST}"
 
-for LAYER in $(${YQ} ".[]" <<< $LAYERS); do 
-    cp -f "${IMAGE_DIR}/blobs/${LAYER}" "${BLOBS_DIR}/${LAYER}.tar.gz"
-done
+  for LAYER in $(${YQ} ".[]" <<< $LAYERS); do
+    cp_f_with_mkdir "${IMAGE_DIR}/blobs/${LAYER}" "${BLOBS_DIR}/${LAYER}.tar.gz"
+  done
 
-repo_tags="${REPOTAGS}" \
-config="blobs/${CONFIG_DIGEST}" \
-layers="${LAYERS}" \
-"${YQ}" eval \
-        --null-input '.[0] = {"Config": env(config), "RepoTags": "${repo_tags}" | envsubst | split("%") | map(select(. != "")) , "Layers": env(layers) | map( "blobs/" + . + ".tar.gz") }' \
-        --output-format json > "${STAGING_DIR}/manifest.json"
+  repo_tags="${REPOTAGS}" \
+  config="blobs/${CONFIG_DIGEST}" \
+  layers="${LAYERS}" \
+  "${YQ}" eval \
+          --null-input '.[0] = {"Config": env(config), "RepoTags": "${repo_tags}" | envsubst | split("%") | map(select(. != "")) , "Layers": env(layers) | map( "blobs/" + . + ".tar.gz") }' \
+          --output-format json > "${STAGING_DIR}/manifest.json"
+fi
 
 # TODO: https://github.com/bazel-contrib/rules_oci/issues/217
-tar -C "${STAGING_DIR}" -cf "${TARBALL_PATH}" manifest.json blobs
+cd "${STAGING_DIR}"
+tar -cf "${TARBALL_PATH}" *