test(docker): build docker by CI

Signed-off-by: Klagarge <remi@heredero.ch>

.gitlab-ci.yml

@@ -5,6 +5,7 @@ default:
   image: $DOCKER_IMAGE
 
 stages:
+  - build-docker
   - lint
   - test
 
@@ -51,3 +52,21 @@ pages:
     expire_in: 7 days
   only:
     - main
+
+# This job runs only when Dockerfile changes
+docker-build:
+  image: docker:latest
+  stage: build-docker
+  services:
+    - docker:dind
+  script:
+    - docker build -t $DOCKER_IMAGE -f Dockerfile .
+    - echo $CI_REGISTRY_PASSWORD | docker login -u $CI_REGISTRY_USER --password-stdin $CI_REGISTRY
+    - docker push $DOCKER_IMAGE
+  rules:
+    - if: $GITLAB_CI == 'false' # Only run in GitLab CI
+      when: never
+    - changes:
+        - Dockerfile
+        - src/pyproject.toml
+        - src/pdm.lock