hack/build-and-push.sh: fix digest existence check

The current check queries Quay's custom API and expects that the tags
in the response always exist. This is not the case for deleted/expired
tags. See for example:

    curl 'https://quay.io/api/v1/repository/redhat-appstudio-tekton-catalog/pull-request-builds/tag/?specificTag=buildah-0.1-2f4e137b5ed645c6d5279c52eaf1d20b071729f1'

    {
      "tags": [
        {
          "name": "buildah-0.1-2f4e137b5ed645c6d5279c52eaf1d20b071729f1",
          "reversion": false,
          "start_ts": 1709804197,
          "end_ts": 1711038680,
          "manifest_digest": "sha256:ebb2fe8fe89005229962167b9a31015a023a49a7169c52edfc34d18fcb1270dd",
          "is_manifest_list": false,
          "size": 5920,
          "last_modified": "Thu, 07 Mar 2024 09:36:37 -0000",
          "expiration": "Thu, 21 Mar 2024 16:31:20 -0000"
        }
      ],
      "page": 1,
      "has_additional": false
    }

This tag has expired (and Quay reports it as such), but our script does
not notice that.

Fix the problem by using `skopeo inspect` instead of querying Quay's
custom API.

Signed-off-by: Adam Cmiel <[email protected]>

hack/build-and-push.sh

@@ -96,17 +96,17 @@ do
     repository=${TEST_REPO_NAME:-task-${task_name}}
     tag=${TEST_REPO_NAME:+${task_name}-}${task_version}
     task_bundle=quay.io/$MY_QUAY_USER/${repository}:${tag}
-    digest=$(curl -s https://quay.io/api/v1/repository/$MY_QUAY_USER/$repository/tag/?specificTag=${tag}-${task_file_sha} | yq '.tags[0].manifest_digest')
-    if [ "$digest" == "null" ]; then
+
+    if digest=$(skopeo inspect --no-tags --format='{{.Digest}}' docker://"${task_bundle}-${task_file_sha}" 2>/dev/null); then
+      task_bundle_with_digest=${task_bundle}@${digest}
+    else
       output=$(tkn bundle push -f "$prepared_task_file" "$task_bundle" | save_ref "$task_bundle" "$OUTPUT_TASK_BUNDLE_LIST")
       echo "$output"
       task_bundle_with_digest="${output##*$'\n'}"
 
       # copy task to new tag pointing to commit where the file was changed lastly, so that image persists
       # even when original tag is updated
       skopeo copy "docker://${task_bundle}" "docker://${task_bundle}-${task_file_sha}"
-    else
-      task_bundle_with_digest=${task_bundle}@${digest}
     fi
     # version placeholder is removed naturally by the substitution.
     real_task_name=$(yq e '.metadata.name' "$prepared_task_file")