Generic Gitlab CI file to build and push a Docker container to the private registry using kaniko (no Docker in Docker privileged mode needed)

.gitlab-ci.yaml

image: docker:latest

stages:
  - build
  
build:
  stage: build
  only:
    - master
  image:
    name: gcr.io/kaniko-project/executor:debug
    entrypoint: [""]
  script:
    - echo "{\"auths\":{\"$CI_REGISTRY\":{\"username\":\"$CI_REGISTRY_USER\",\"password\":\"$CI_REGISTRY_PASSWORD\"}}}" > /kaniko/.docker/config.json
    - /kaniko/executor --context $CI_PROJECT_DIR --dockerfile $CI_PROJECT_DIR/Dockerfile --destination $CI_REGISTRY_IMAGE:latest