Build multi-arch image.

This will build only those architectures that we have runners to build on

.gitlab-ci.yml

@@ -1,3 +1,7 @@
+stages:
+  - test
+  - deploy
+  - container-build
 
 variables:
   DEBIAN_FRONTEND: noninteractive
@@ -275,14 +279,45 @@ release-job:
           url: '${CI_PROJECT_URL}/-/jobs/${TAR_JOB_ID}/artifacts/file/${CI_PROJECT_NAME}-${CI_COMMIT_TAG}.tar.gz'
  
 build-container:
-  stage: deploy
+  variables:
+    TAG: latest
+  stage: container-build
+  parallel:
+    matrix:
+      - ARCH: amd64
+      - ARCH: arm64
+      - ARCH: s390x
+  tags:
+    - $ARCH
   image:
-    name: gcr.io/kaniko-project/executor:v1.14.0-debug
+    name: gcr.io/kaniko-project/executor:debug
     entrypoint: [""]
   script:
-    - /kaniko/executor
+    - if [ -n "$CI_COMMIT_TAG" ]; then TAG="$CI_COMMIT_TAG"; fi
+    - >-
+      /kaniko/executor
       --context "${CI_PROJECT_DIR}"
       --dockerfile "${CI_PROJECT_DIR}/Dockerfile"
-      --destination "${CI_REGISTRY_IMAGE}:${CI_COMMIT_TAG}"
+      --destination "${CI_REGISTRY_IMAGE}:${TAG}_${ARCH}"
-  rules:
+
-    - if: $CI_COMMIT_TAG
+merge-manifests:
+  variables:
+    TAG: latest
+  stage: container-build
+  needs:
+    - job: build-container
+      artifacts: false
+  image:
+      name: mplatform/manifest-tool:alpine
+      entrypoint: [""]
+  script:
+    - if [ -n "$CI_COMMIT_TAG" ]; then export TAG="$CI_COMMIT_TAG"; fi
+    - >-
+      manifest-tool
+      --username="${CI_REGISTRY_USER}"
+      --password="${CI_REGISTRY_PASSWORD}"
+      push from-args
+      --platforms linux/amd64,linux/arm64,linux/s390x
+      --template "${CI_REGISTRY_IMAGE}:${CI_COMMIT_TAG}_ARCH"
+      --target "${CI_REGISTRY_IMAGE}:${TAG}"
+