CentOS 7 OpenVZ NetworkManager issues.

There is an issue with CentOS 7 containers on OpenVZ nodes, where NetworkManager service breaks the network, and only localhost 127.0.0.1 network interface is coming up.

When you try to check network interfaces, and IP address on the server, you will only see localhost interface.

[email protected] [/]# ifconfig
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 9059 bytes 1539654 (1.4 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 9059 bytes 1539654 (1.4 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

When issuing service network restart you will and output like this:

Starting network (via systemctl): Job for network.service failed because the control process exited with error code. See "systemctl status network.service" and "journalctl -xe" for details.
[FAILED]

When you run journalctl -xe you will see errors like this:

-- Unit network.service has begun starting up.
 Feb 16 05:16:40 server network[2262]: Bringing up loopback interface: Could not load file '/etc/sysconfig/network-scripts/ifcfg-Feb 16 05:16:40 server network[2262]: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
 Feb 16 05:16:40 server network[2262]: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
 Feb 16 05:16:40 server network[2262]: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
 Feb 16 05:16:40 server network[2262]: [ OK ]
 Feb 16 05:16:40 server network[2262]: Bringing up interface venet0: Error: Connection activation failed: No suitable device founFeb 16 05:16:40 server network[2262]: [FAILED]
 Feb 16 05:16:40 server network[2262]: RTNETLINK answers: File exists
 Feb 16 05:16:40 server network[2262]: RTNETLINK answers: File exists
 Feb 16 05:16:40 server network[2262]: RTNETLINK answers: File exists
 Feb 16 05:16:40 server network[2262]: RTNETLINK answers: File exists
 Feb 16 05:16:40 server network[2262]: RTNETLINK answers: File exists
 Feb 16 05:16:40 server network[2262]: RTNETLINK answers: File exists
 Feb 16 05:16:40 server network[2262]: RTNETLINK answers: File exists
 Feb 16 05:16:40 server network[2262]: RTNETLINK answers: File exists
 Feb 16 05:16:40 server network[2262]: RTNETLINK answers: File exists
 Feb 16 05:16:40 server systemd[1]: network.service: control process exited, code=exited status=1
 Feb 16 05:16:40 server systemd[1]: Failed to start LSB: Bring up/down networking.
 -- Subject: Unit network.service has failed
 -- Defined-By: systemd
 -- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
 --
 -- Unit network.service has failed.
 --
 -- The result is failed.
 Feb 16 05:16:40 server systemd[1]: Unit network.service entered failed state.
 Feb 16 05:16:40 server systemd[1]: network.service failed.
 Feb 16 05:16:40 server polkitd[226]: Unregistered Authentication Agent for unix-process:2257:65393 (system bus name :1.37, object

Issue can be resolved by stopping and disabling the NetworkManager service.

[email protected] [/]# service NetworkManager stop
Redirecting to /bin/systemctl stop NetworkManager.service
[email protected] [/]# chkconfig NetworkManager off

You can also uninstall NetworkManager completely.

References:

https://lists.openvz.org/pipermail/users/2015-December/006691.html

Openvz / CentOS 7 – Network Manager can break networking

 

systemd conflicts with initscripts during yum update

When running yum update on CentOS 7 OpenVZ container you might get a following error:

--> Processing Conflict: systemd-219-19.el7.x86_64 conflicts initscripts < 9.49.28-1 
--> Finished Dependency Resolution
Error: systemd conflicts with initscripts-9.49.17-1.el7.x86_64
 You could try using --skip-broken to work around the problem
 You could try running: rpm -Va --nofiles --nodigest

Exact version I was running on this server is CentOS Linux release 7.1.1503 (Core), and updates were failing due to them requiring a newer systemd version, which required a newer version, v9.49.28 at least,  of initscripts installed.

Reason why systemd was conflicting with current version of initscripts, instead of just updating them to newer version, was that initscripts were excluded from update in yum.conf file.

[[email protected] ~]# grep exclude /etc/yum.conf
exclude=initscripts*

There are no default exclude packages in default CentOS/RHEL installs, and it wasn’t put there by me, so question is why was initscripts excluded from updates.

Issues with initscripts v9.49.24 in CentOS 7 OpenVZ containers

It turns out there were some issues with initscripts v9.49.24, which seemed to introduce problems with network connectivity on CentOS 7 OpenVZ VPS machines.

https://vpsboard.com/topic/1908-creating-cpanel-openvz-template-wwhm-setup-wizard-fix/?page=2
https://forum.proxmox.com/threads/centos-7-openvz-template-in-pve-3-4-issues.21808/

I commented out exclude=initscripts* from yum.conf, and checked the currently available version.

[[email protected] ~]# grep exclude /etc/yum.conf
#exclude=initscripts*
[[email protected] ~]# yum check-updates initscripts
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.greenmountainaccess.net
 * epel: mirror.nexcess.net
 * extras: mirrors.lga7.us.voxel.net
 * updates: mirror.dattobackup.com
 * webtatic: us-east.repo.webtatic.com

initscripts.x86_64                                               9.49.30-1.el7                                                base

Current version is v9.49.30, so I presumed issues with v9.49.24 were corrected in this version, and proceeded with the update.

Update has completed successfully, and all packages including initscrips were updated to latest version, as was CentOS.

[[email protected] ~]# cat /etc/redhat-release
CentOS Linux release 7.2.1511 (Core)

I haven’t noticed any network or any other issues on the VPS after the upgrade, so it seems any network issues from v9.49.24, don’t exist in v9.49.30.

[[email protected] ~]# rpm -qa | grep initscripts
initscripts-9.49.30-1.el7.x86_64