wrong variable name in gitlab-ci

SSS_USER

master-deploy:
  stage: deploy
  image: collaborating.tuhh.de:5005/cfg0846/research-topics-mat-tuhh/alpine-ssh
  before_script:
    - eval $(ssh-agent -s)
    - echo "$SSH_PRIVATE_KEY" | tr -d '\r' | ssh-add -
    - mkdir -p ~/.ssh && touch ~/.ssh/known_hosts
    - echo "$SSH_KNOWN_HOSTS" > ~/.ssh/known_hosts
    - chmod 700 ~/.ssh/known_hosts
  script:
    - echo "$SSH_KNOWN_HOSTS" > ~/.ssh/known_hosts
    - chmod 644 ~/.ssh/known_hosts
    - eval $(ssh-agent -s)
    - echo "$SSH_PRIVATE_KEY" | tr -d '\r' | ssh-add - > /dev/null
    - rsync -v -r -a --delete -e  "ssh -p${SSH_PORT}" build-tuhh-asteroid/* ${SSH_USER}@${HOST_NAME}:/usr/local/apache2/htdocs/.
    - ssh -v -p "${SSH_PORT}" "${SSH_USER}"@"${HOST_NAME}" "rm -rf /usr/local/apache2/htdocs/.htaccess" #only temporary fix
  cache:
    key: "$CI_COMMIT_REF_SLUG"
  environment:
    name: $CI_COMMIT_REF_NAME
    url: https://$PROXY_HOST_NAME$BASE_DIR
  rules:
   # - if: $SSH_USER #use this only for testing
   - if: $CI_COMMIT_REF_NAME == "master" && $SSS_USER