https://docs.gitlab.com/runner/install/docker.html

安装 runner

docker run -d --name gitlab-runner --restart always \
     -v /srv/gitlab-runner/config:/etc/gitlab-runner \
     -v /var/run/docker.sock:/var/run/docker.sock \
     gitlab/gitlab-runner:latest

注册 runner

https://docs.gitlab.com/runner/register/index.html#docker

使用 docker 的方式注册 runner 时，最后一步会提示输入默认 docker 镜像，提示语如下：

If you entered docker as your executor, you’ll be asked for the default image to be used for projects that do not define one in .gitlab-ci.yml

输入 alpine:latest即可。