DOCKER_CERT_PATH on gitlab shared runners

Question

Colleagues, hello. I'm learning how to set up ci/cd and deployment for production. I use the shared runners gitlab. And I don't understand how I can specify DOCKER_CERT_PATH in gitlab shared runners . If I understood correctly, DOCKER_CERT_PATH is the path to the local folder on the runner machine. So I need to use my personal runner only? And on my personal runner I have to add certificates to the local folder, and specify it in DOCKER_CERT_PATH?

I am wonna use gitlab-ci config like this -

    .deploy-script: &deploy-script
      script:
        - docker-compose -f docker-compose.base.yml -f docker-compose.$CI_COMMIT_REF_SLUG.yml pull
        - docker-compose -f docker-compose.base.yml -f docker-compose.$CI_COMMIT_REF_SLUG.yml up -d -V
        - docker image prune -af

    deploy:staging:
      stage: deploy
      environment:
        name: staging
        url: '$SERVER_PROTOCOL://$SERVER_NAME_DEV'
      variables:
        DOCKER_TLS_VERIFY: '1'
        DOCKER_HOST: 'tcp://$SERVER_IP_DEV:2376'
        DOCKER_CERT_PATH: '/certs/${CI_PROJECT_PATH_SLUG}-staging/'
        SERVER_NAME: '${SERVER_NAME_DEV}'
      <<: *deploy-script
      only:
        - dev