Merge branch 'kaniko' into 'main'

Use Kaniko for image builds

See merge request !20

.gitlab-ci.yml

-docker-build:
-  image: docker:24-dind
-
-  variables:
-    DOCKER_HOST: tcp://docker:2375
-    DOCKER_DRIVER: overlay2
-    DOCKER_TLS_CERTDIR: ""
-
-  services:
-    - name: docker:24-dind
-      alias: docker
-      command: ["--tls=false"]
-
-  before_script:
-    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
-  # Default branch leaves tag empty (= latest tag)
-  # All other branches are tagged with the escaped branch name (commit ref slug)
+build:
+  stage: build
+  image:
+    name: gcr.io/kaniko-project/executor:v1.9.0-debug
+    entrypoint: [""]
   script:
     - |
       if [[ "$CI_COMMIT_BRANCH" == "$CI_DEFAULT_BRANCH" ]]; then
-        tag=""
+        tag="latest"
         echo "Running on default branch '$CI_DEFAULT_BRANCH': tag = 'latest'"
       else
-        tag=":$CI_COMMIT_REF_NAME"
+        tag="$CI_COMMIT_REF_NAME"
         echo "Running on branch '$CI_COMMIT_BRANCH': tag = $tag"
       fi
-    - docker build --pull -t "$CI_REGISTRY_IMAGE${tag}" .
-    - docker push "$CI_REGISTRY_IMAGE${tag}"
-  # Run this job in a branch where a Dockerfile exists
+    - /kaniko/executor
+      --context "${CI_PROJECT_DIR}"
+      --build-arg http_proxy=$http_proxy
+      --build-arg https_proxy=$https_proxy
+      --build-arg no_proxy=$no_proxy
+      --dockerfile "${CI_PROJECT_DIR}/Dockerfile"
+      --destination "$CI_REGISTRY_IMAGE:${tag}"
   rules:
     - if: $CI_COMMIT_BRANCH
       exists: