Gitlab deploy to branch

.gitlab-ci.yml

stages:
  - build
  - deploy
build:
  stage: build
  image: node:11
  before_script:
    - npm install --progress=false --unsafe-perm
  script:
    - npm run build
  artifacts:
    expire_in: 100 yrs
    paths:
      - public
  cache:
    paths:
      - node_modules/
deploy:
  stage: deploy
  only:
    - master
  image: debian:stable
  before_script:
  - apt-get update
  - apt-get install -y git
  - mkdir -p ~/.ssh
  - echo "$SSH_PRIVATE_KEY" | tr -d '\r' > ~/.ssh/id_rsa
  - chmod 600 ~/.ssh/id_rsa
  - ssh-keyscan -H gitlab.com >> ~/.ssh/known_hosts
  - git config --global user.email "[email protected]"
  - git config --global user.name "GitLab CI"
  script:
  - git clone --depth 1 --single-branch -b deploy [email protected]:yourname/yourrepo.git deploy
  - mv deploy/.git deploy-.git
  - rm -rf deploy
  - mkdir deploy
  - mv deploy-.git deploy/.git
  - cd deploy
  - cp -r ../public/* .
  - git add .
  - git diff --staged --quiet || git commit -m "Update pages"
  - git push