Changing builder image in ci pipeline

Bug Description

Following the OTG0154122 The old docker-image-builder is no longer working properly. As immaediate effect the cern-drupal-distribution pipeline cannot build anymore new images.

CERN Gitlab team suggest to use the kaniko image.

Solution implemented

In this MR the gitlac_ci.yml file has been modified to accomodate such changes following the guidelines provided below https://gitlab.cern.ch/gitlabci-examples/build_docker_image/-/blob/master/.gitlab-ci.yml?ref_type=heads#L19

In particular the image has been changed from name: gitlab-registry.cern.ch/ci-tools/docker-image-builder to name: gcr.io/kaniko-project/executor:debug

.gitlab-ci.yml

@@ -7,15 +7,18 @@ stages:
 
 .build_image: &build_image
   image:
-    # We recommend using the CERN version of the Kaniko image: gitlab-registry.cern.ch/ci-tools/docker-image-builder
-    name: gitlab-registry.cern.ch/ci-tools/docker-image-builder
+    # The kaniko debug image is recommended because it has a shell, and a shell is required for an image to be used with GitLab CI/CD.
+    name: gcr.io/kaniko-project/executor:debug
     entrypoint: [""]
   script:
-      # This is not the common Authentication config, unknown reason why common config fails
-    - echo "{\"auths\":{\"$CI_REGISTRY\":{\"auth\":\"$(echo -n ${CI_REGISTRY_USER}:${CI_REGISTRY_PASSWORD} | base64)\"}}}" > /kaniko/.docker/config.json
-    - /kaniko/executor --context "$CI_PROJECT_DIR/$CONTEXT_DIR" --dockerfile "$CI_PROJECT_DIR/$CONTEXT_DIR/$DOCKERFILE"
-      --destination "${CI_REGISTRY_IMAGE}/${IMAGE_NAME}:${TAG}" $BUILD_ARGS
-    - echo "Image pushed to ${CI_REGISTRY_IMAGE}/${IMAGE_NAME}:${TAG}"
+      # define script variables, they are passed in build time
+    - IMAGE_DESTINATION=${CI_REGISTRY_IMAGE}/${IMAGE_NAME}:${TAG}
+      # Prepare Kaniko configuration file
+    - echo "{\"auths\":{\"$CI_REGISTRY\":{\"username\":\"$CI_REGISTRY_USER\",\"password\":\"$CI_REGISTRY_PASSWORD\"}}}" > /kaniko/.docker/config.json
+     # Build and push the image from the Dockerfile at the root of the project.
+    - /kaniko/executor --context "$CI_PROJECT_DIR/$CONTEXT_DIR" --dockerfile "$CI_PROJECT_DIR/$CONTEXT_DIR/$DOCKERFILE" --destination "${IMAGE_DESTINATION}" $BUILD_ARGS
+      # Print the full registry path of the pushed image
+    - echo "Image pushed to ${IMAGE_DESTINATION}"
 
 environment:
   stage: environment