GitLab Docker Image Publish CI

.gitlab-ci.yml

build:
    image: docker:latest
    stage: build
    services:
        - docker:dind
    variables:
        IMAGE_TAG: $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG
        LATEST_TAG: $CI_REGISTRY_IMAGE:latest
    script:
        - echo "$CI_REGISTRY_PASSWORD" | docker login $CI_REGISTRY -u $CI_REGISTRY_USER --password-stdin
        - docker build -t $IMAGE_TAG .
        - docker push $IMAGE_TAG
        - |
            if [ "$CI_COMMIT_REF_SLUG" = "main" ]; then
              docker tag $IMAGE_TAG $LATEST_TAG
              docker push $LATEST_TAG
            fi