Automatically detect if prefix library/ is needed

.github/workflows/test.yml

@@ -8,9 +8,9 @@ on:
   pull_request:
 
 jobs:
-  test:
+  test1:
     name: Test-Action
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     continue-on-error: true
     steps:
       - name: Checkout Repository
@@ -26,3 +26,21 @@ jobs:
       - name: Check value
         run: echo "Needs updating"
         if: steps.test.outputs.needs-updating == 'true'
+  test2:
+    name: Test-Action
+    runs-on: ubuntu-22.04
+    continue-on-error: true
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v2
+      - name: Test Action
+        id: test
+        uses: ./
+        with:
+          base-image: nginx:1.21.0
+          image: library/nginx:1.21.0
+      - name: Get Test Output
+        run: echo "Workflow Docker Image ${{ steps.test.outputs.needs-updating }}"
+      - name: Check value
+        run: echo "Does not need updating"
+        if: steps.test.outputs.needs-updating == 'false'

docker.sh

@@ -14,8 +14,12 @@ get_layers() {
     digestOutput=$(curl -H "Authorization: Bearer $token" \
         -H "Accept: application/vnd.docker.distribution.manifest.v2+json" \
         "https://index.docker.io/v2/${repo}/manifests/${digest}" 2>/dev/null)
-
-    jq -r '[.layers[].digest]' <<<"$digestOutput"
+
+    if jq -e -r '.errors[0].code' <<<"$digestOutput" >/dev/null; then
+        jq -r '.errors[0].code' <<<"$digestOutput"
+    else
+        jq -r '[.layers[].digest]' <<<"$digestOutput"
+    fi
 }
 
 get_token() {
@@ -25,10 +29,26 @@ get_token() {
     curl "$url" 2>/dev/null | jq -r '.token'
 }
 
+# if we get a "UNAUTHORIZED" response and the $base does not match a image with username -> fallback to a version with "library" as prefix
+retry_if_necessary() {
+    local IMAGE_PATTERN_WITH_USERNAME="^.+/.+$"
+    local repo=$1
+    local digest=$2
+    local result
+
+    result=$(get_layers "$repo" "$digest")
+
+    if [[ $result == "UNAUTHORIZED" ]] && ! [[ $repo =~ $IMAGE_PATTERN_WITH_USERNAME ]] ; then
+        result=$(get_layers "library/$repo" "$digest")
+    fi
+
+    echo "$result"
+}
+
 IFS=: read base base_tag <<<$base
 IFS=: read image image_tag <<<$image
 
-layers_base=$(get_layers $base ${base_tag:-latest})
-layers_image=$(get_layers $image ${image_tag:-latest})
+layers_base=$(retry_if_necessary $base ${base_tag:-latest})
+layers_image=$(retry_if_necessary $image ${image_tag:-latest})
 
 jq '.base-.image | .!=[]' <<<"{\"base\": $layers_base, \"image\": $layers_image }"