ci: output manifest tarball with Oras (#3698)

* ci: output manifest tarball

* chore: reset file

* test: ob var

Author: jpayne3506

.pipelines/build/manifests.jobs.yaml

@@ -36,3 +36,31 @@ jobs:
         image_repository: ${{ job_data.templateContext.name }}
         image_tag: ${{ job_data.templateContext.image_tag }}
         manifest_data: $(MANIFEST_JSON)
+
+  - job: ${{ job_data.job }}_package_manifest
+    displayName: "Package Image Manifest - ${{ job_data.job }}"
+    dependsOn:
+    - ${{ job_data.job }}_publish_manifest
+    pool:
+      type: linux
+    variables:
+      LinuxContainerImage: 'mcr.microsoft.com/onebranch/azurelinux/build:3.0'
+      ob_outputDirectory: $(Build.SourcesDirectory)/out
+      ob_git_checkout: false
+    steps:
+    # Leverage new feature from https://github.com/oras-project/oras/issues/1366 in the future
+    # :v1 has no impact, but is required for oras
+    # Copy manifest from ACR
+    - bash: |
+        oras copy $(ACR).azurecr.io/$(IMAGE_REPO_PATH)/${{ job_data.templateContext.name }}:${{ job_data.templateContext.image_tag }} \
+        --to-oci-layout ./${{ job_data.templateContext.image_tag }}_artifact:v1
+      name: oras_copy
+      displayName: "Oras Copy"
+
+    # Generate tarball
+    - bash: |
+        TARGET_DIR=$(ob_outputDirectory)
+        mkdir -p "$TARGET_DIR"
+        tar -cvzf ${TARGET_DIR}/${{ job_data.templateContext.image_tag }}_artifact.tar.gz ./${{ job_data.templateContext.image_tag }}_artifact
+      name: tarball
+      displayName: "Generate tarball"