Category: System Setting Other Debugs (系统设置其它排错)

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[排错] RHEL 8 及以上解决系统升级 Nginx 后使用 yum 命令时显示警告 “Problem: module……,but none of the providers can be installed”

报错代码

 Problem: module php:7.2:820181215112050:76554e01.x86_64 from rhel-8-for-x86_64-appstream-rpms requires module(nginx:1.14), but none of the providers can be installed
  - module nginx:1.14:820181214004940:9edba152.x86_64 from rhel-8-for-x86_64-appstream-rpms conflicts with module(nginx:1.24) provided by nginx:1.24:8100020240119085512:e155f54d.x86_64 from rhel-8-for-x86_64-appstream-rpms
  - module nginx:1.24:8100020240119085512:e155f54d.x86_64 from rhel-8-for-x86_64-appstream-rpms conflicts with module(nginx:1.14) provided by nginx:1.14:820181214004940:9edba152.x86_64 from rhel-8-for-x86_64-appstream-rpms
  - module nginx:1.14:8000020190830002848:f8e95b4e.x86_64 from rhel-8-for-x86_64-appstream-rpms conflicts with module(nginx:1.24) provided by nginx:1.24:8100020240119085512:e155f54d.x86_64 from rhel-8-for-x86_64-appstream-rpms
  - module nginx:1.24:8100020240119085512:e155f54d.x86_64 from rhel-8-for-x86_64-appstream-rpms conflicts with module(nginx:1.14) provided by nginx:1.14:8000020190830002848:f8e95b4e.x86_64 from rhel-8-for-x86_64-appstream-rpms
  - conflicting requests
Dependencies resolved.

解决方法一：禁用所有和 nginx 模块有关联的 php 模块

# dnf module disable php

解决方法二：开启最新版本的 php 模块

# dnf module reset php && dnf module enable php:7.2

（补充：这里以设置 php:7.2 模块为例）

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[排错] Linux 解决 SSSD 用户导致本地用户无法创建的问题 （本地用户名称和 SSSD 里的用户名称冲突导致本地用户名称无法被创建）

报错现象

创建这个用户时报错这个用户已经创建
删除这个用户时报错这个用户不存在
使用 id 命令检查这个用户时会显示此用户

确认方法：检查某个用户名有没有被域名占用

# getent passwd -s sss mingyuzhu

（补充：这里以检查某个用户名有没有被域名占用为例）

解决方法方法一：临时禁用 SSSD 解析

1.1 修改 /etc/nsswitch.conf 配置文件

# vi /etc/nsswitch.conf

将以下内容：

......
passwd:     files systemd
......

修改为：

......
#passwd:     files systemd
......

1.2 让刚刚修改的配置文件生效

# systemctl restart sssd

解决方法二：在 SSSD 服务中忽略某用户

2.1 修改 /etc/sssd.conf 配置文件

# vi /etc/sssd.conf

添加以下内容：

......
[nss]
filter_users = mingyuzhu

（补充：这里以忽略 mingyuzhu 用户为例）

2.2 让刚刚修改的配置文件生效

# systemctl restart sssd

参考文献

https://access.redhat.com/solutions/3442161

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[排错] 解决 Linux 启动时某些服务没有开机自启 （日志里报错： “deleted to break ordering cycle starting”）

报错代码

某些服务没有开机自启例如 NetworkManager.service

原因分析

在系统日志里可以类似 …… Job network.target/start deleted to break ordering cycle starting with …… 报错例如：

# cat /var/log/messages
Jan 1 10:09:24 server systemd[1]: network-online.target: Found ordering cycle on network.target/start
Jan 1 10:09:24 server systemd[1]: network-online.target: Found dependency on NetworkManager.service/start
Jan 1 10:09:24 server systemd[1]: network-online.target: Found dependency on basic.target/start
Jan 1 10:09:24 server systemd[1]: network-online.target: Found dependency on slices.target/start
Jan 1 10:09:24 server systemd[1]: network-online.target: Found dependency on mysql.slice/start
Jan 1 10:09:24 server systemd[1]: network-online.target: Found dependency on remote-fs.target/start
Jan 1 10:09:24 server systemd[1]: network-online.target: Found dependency on remote-fs-pre.target/start
Jan 1 10:09:24 server systemd[1]: network-online.target: Found dependency on iscsi.service/start
Jan 1 10:09:24 server systemd[1]: network-online.target: Found dependency on network-online.target/start
Jan 1 10:09:24 server systemd[1]: network-online.target: Job network.target/start deleted to break ordering cycle starting with network-online.target/start
Jan 1 10:09:24 server systemd[1]: NetworkManager-wait-online.service: Found ordering cycle on NetworkManager.service/start
Jan 1 10:09:24 server systemd[1]: NetworkManager-wait-online.service: Found dependency on basic.target/start
Jan 1 10:09:24 server systemd[1]: NetworkManager-wait-online.service: Found dependency on slices.target/start
Jan 1 10:09:24 server systemd[1]: NetworkManager-wait-online.service: Found dependency on mysql.slice/start
Jan 1 10:09:24 server systemd[1]: NetworkManager-wait-online.service: Found dependency on remote-fs.target/start
Jan 1 10:09:24 server systemd[1]: NetworkManager-wait-online.service: Found dependency on remote-fs-pre.target/start
Jan 1 10:09:24 server systemd[1]: NetworkManager-wait-online.service: Found dependency on iscsi.service/start
Jan 1 10:09:24 server systemd[1]: NetworkManager-wait-online.service: Found dependency on network-online.target/start
Jan 1 10:09:24 server systemd[1]: NetworkManager-wait-online.service: Found dependency on NetworkManager-wait-online.service/start
Jan 1 10:09:24 server systemd[1]: NetworkManager-wait-online.service: Job NetworkManager.service/start deleted to break ordering cycle starting with NetworkManager-wait-online.service/start

从案例中日志里的内容可以判断：
1) network.target/NetworkManager.service 启动
2) NetworkManager.service 作为基础服务依赖 basic.target
3) basic.target 依赖所有 slice 包括 mysql.slice
4) mysql.slice 依赖 iscsi.service/remote-fs.target/remote-fs-pre.target
5) iscsi.service/remote-fs.target/remote-fs-pre.target 依赖 network.target/NetworkManager.service
6) 系统为了防止启动时陷入死循环，systemd 报错 Job NetworkManager.service/start deleted to break ordering cycle 并放弃启动 NetworkManager.service

解决方法

取消不太重要的服务的依赖要求

# vi /etc/systemd/system/mysql.slice

将以下内容：

......
Before=slices.target
Wants=-.slice
After=-.slice remote-fs.target
......

修改为：

......
Before=slices.target
Wants=-.slice
After=-.slice #remote-fs.target
......

（
补充：
1) 这里以取消使用 /etc/systemd/system/mysql.slice 文件的服务的依赖要求为例
2) 这里以注释掉 After=-.slice remote-fs.target 中的 remote-fs.target 为例
）