added cache for kaniko

.gitlab-ci.yml

@@ -18,6 +18,9 @@ docker:
     - echo "{\"auths\":{\"$CI_REGISTRY\":{\"username\":\"$CI_REGISTRY_USER\",\"password\":\"$CI_REGISTRY_PASSWORD\"}}}" > /kaniko/.docker/config.json
     - |
         /kaniko/executor \
+          --cache \
+          --cache-copy-layers \
+          --cache-repo="${CI_REGISTRY_IMAGE}/cache" \
           --context "${CI_PROJECT_DIR}" \
           --dockerfile "${CI_PROJECT_DIR}/Dockerfile" \
           --destination "${CI_REGISTRY_IMAGE}:${CONTAINER_TAG}"