ci: added job to build the docker image

.gitlab-ci.yml

+default:
+  interruptible: true
+  artifacts:
+    expire_in: 30 days
+
+stages:
+  - build
+
+build_docker_image:
+  image:
+    name: gcr.io/kaniko-project/executor:debug
+    entrypoint: [ "" ]
+  stage: build
+  rules:
+    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH && $CI_COMMIT_REF_PROTECTED == "true"
+    - if: $CI_COMMIT_TAG =~ /^[0-9]+\.[0-9]+\.([0-9]|[0-z])+$/
+  before_script:
+    - if [ -n "$CI_COMMIT_TAG" ]; then export DOCKER_TAG=$CI_COMMIT_TAG; else export DOCKER_TAG=$CI_COMMIT_SHA; fi
+  script:
+    - echo "{\"auths\":{\"${CI_REGISTRY}\":{\"username\":\"${CI_REGISTRY_USER}\",\"password\":\"${CI_REGISTRY_PASSWORD}\"}}}" > /kaniko/.docker/config.json
+    - /kaniko/executor
+      --context $CI_PROJECT_DIR
+      --target production
+      --skip-unused-stages
+      --destination $CI_REGISTRY_IMAGE/frontend:$DOCKER_TAG
+      --destination $CI_REGISTRY_IMAGE/frontend:latest

Dockerfile

@@ -16,5 +16,3 @@ FROM nginx:alpine as production
 COPY default.conf /etc/nginx/conf.d/default.conf
 
 COPY --from=builder /app/dist/frontend/browser /usr/share/nginx/html
-
-