After moving host interface to the secondary OVS bridge the host lost DNS config

antrea-io / antrea

Kubernetes networking based on Open vSwitch

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After moving host interface to the secondary OVS bridge the host lost DNS config #6558

Open jianjuns opened 4 months ago

jianjuns commented 4 months ago

Describe the bug In a secondary network test by @meibensteiner, after the node's primary interface is moved to the secondary OVS bridge, the node lost its DNS config in /etc/resolv.conf.

cat /etc/resolv.conf
# Generated by NetworkManager

It may be an interoperability issue with NetworkManager.

To Reproduce

cloud-init with the most straight forward settings for formatting and networking
networking via ipv4 DHCP, no proxy or anything alike
Basic RKE2 without CNI
Install Antrea (configured node's primary interface for secondary network OVS bridge)

Versions: It happened in cluster with both Ubuntu 24.04 and Debian 12 nodes.

meibensteiner commented 3 months ago

This issue is probably caused by systemd-resolved. Adding a static dns server in /etc/systemd/resolved.conf fixes it.

[Resolve]
DNS=192.168.1.254

luolanzone commented 3 months ago

Hi @meibensteiner , thanks for the update, systemd-resolved will update /etc/resolv.conf whenever there is a change in network configuration, DNS settings, or when the service is restarted or reloaded. You can try to run chattr +i /etc/resolv.conf command to make the file immutable to avoid the file being modified again.

@jianjuns Looks like the issue is not directly with Antrea secondary network feature but systemd-resolved, considering there are several processes can modify the file, I feel it may not be easy to check from Antrea side, any suggestion for next step?

jianjuns commented 3 months ago

But do we know why systemd removed the DNS config? We need to understand if that is because of OVS (e.g. systemd/network manager do not recognize interfaces on the OVS even we keep the original host interface names).

luolanzone commented 3 months ago

Sure, I can check if this can be reproduced locally first.

luolanzone commented 2 months ago

No chance to take a look at this recently, assigning this to @hongliangl to move forward.