问题描述：

如下配置：
external_url设置ip+port（http://10.0.0.100:8000），会出现无法访问GitLab UI。

(如果配置端口80:
external_url 'http://10.0.0.100'
是可以访问的，GitLab默认的http访问端口号为80端口 。)

version: '2'
services:
    gitlab:
      image: 'gitlab/gitlab-ce:12.9.0-ce.0'
      restart: unless-stopped
      hostname: 'gitlab'
      environment:
        TZ: 'Asia/Shanghai'
        GITLAB_OMNIBUS_CONFIG: |
          external_url 'http://10.0.0.100:8000'
      ports:
        - '80:8000'
        - '443:443'
        - '2212:22'
      volumes:
        - /root/gitlab/config:/etc/gitlab
        - /root/gitlab/data:/var/opt/gitlab
        - /root/gitlab/logs:/var/log/gitlab
      logging:
        driver: "json-file"
        options:
          max-file: '3'
          max-size: "20m"

原因：

修改external_url地址为http://10.0.0.100:8000，那GitLab肯定访问不了，因为你已经将内部的端口号修改为8000端口了，而你通过docker run映射出来的端口号是80端口，所以不可能访问到。那该怎么办？

设置的external_url端口就是容器内部服务端口，修改为对应即可，如下：

version: '2'
services:
    gitlab:
      image: 'gitlab/gitlab-ce:12.9.0-ce.0'
      restart: unless-stopped
      hostname: 'gitlab'
      environment:
        TZ: 'Asia/Shanghai'
        GITLAB_OMNIBUS_CONFIG: |
          external_url 'http://10.0.0.100:8000'
      ports:
        - '8000:8000'
        - '443:443'
        - '2212:22'
      volumes:
        - /root/gitlab/config:/etc/gitlab
        - /root/gitlab/data:/var/opt/gitlab
        - /root/gitlab/logs:/var/log/gitlab
      logging:
        driver: "json-file"
        options:
          max-file: '3'
          max-size: "20m"

参考文档：https://www.jianshu.com/p/d707f70c60d2