进入到gitlab容器

[root@localhost gitlab]# docker ps
CONTAINER ID   IMAGE                     COMMAND             CREATED          STATUS                    PORTS                                                                                                         NAMES
d1dc5573a3ab   gitlab/gitlab-ce:latest   "/assets/wrapper"   34 minutes ago   Up 34 minutes (healthy)   0.0.0.0:22->22/tcp, :::22->22/tcp, 0.0.0.0:80->80/tcp, :::80->80/tcp, 0.0.0.0:443->443/tcp, :::443->443/tcp   gitlab
[root@localhost gitlab]# docker exec -it d1 bash
root@gitlab:/#

切换目录：cd /opt/gitlab/bin

root@gitlab:/opt/gitlab/bin# ls
gitlab-backup  gitlab-healthcheck  gitlab-rails  gitlab-redis-cli
gitlab-ctl     gitlab-psql         gitlab-rake   gitlab-ruby

执行 gitlab-rails console production 命令 开始初始化密码

root@gitlab:/opt/gitlab/bin# gitlab-rails console
--------------------------------------------------------------------------------
 Ruby:         ruby 2.7.2p137 (2020-10-01 revision 5445e04352) [x86_64-linux]
 GitLab:       14.1.2 (8c67b499146) FOSS
 GitLab Shell: 13.19.1
 PostgreSQL:   12.6
--------------------------------------------------------------------------------
Loading production environment (Rails 6.1.3.2)
irb(main):001:0>

修改管理员密码

irb(main):002:0> u=User.where(id:1).first
=> #<User id:1 @root>
irb(main):007:0> u.password=12345678
=> 12345678
irb(main):008:0> u.password_confirmation=12345678
=> 12345678
irb(main):009:0> u.save
Enqueued ActionMailer::MailDeliveryJob (Job ID: 2cc5555c-e78f-4865-9be4-89da0d838278) to Sidekiq(mailers) with arguments: "DeviseMailer", "password_change", "deliver_now", {:args=>[#<GlobalID:0x00007f4a85ecbae0 @uri=#<URI::GID gid://gitlab/User/1>>]}
=> true

到这里，root密码已经改成了12345678

使用新的密码进行登陆，可以看到如下的页面

以上就是修改管理员密码的全过程。