How to bind flannel to different interface or all of them?

[hlacikd]

Hello guys,
we are advanced k3s users, but not experienced enough in infrastructure.
We have a customer that has 3 interfaces on server, each has its own network, and we need to be able to access all of them from kubernetes.

RN i see kubernetes was bind to if3, how to configure it to bind to all of them? Create network bridge and bind it to it? What should i set in k3s?

Here is how it looks. cali0f3d1e69ba2 is bind to if3 which is 3: ens192: ? Thanks in advance!

lzzii@x00-lzz-node01:~$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:50:56:80:70:f1 brd ff:ff:ff:ff:ff:ff
    inet 10.84.107.131/24 brd 10.84.107.255 scope global ens160
       valid_lft forever preferred_lft forever
    inet6 fe80::250:56ff:fe80:70f1/64 scope link 
       valid_lft forever preferred_lft forever
3: ens192: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:50:56:80:88:a9 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::250:56ff:fe80:88a9/64 scope link 
       valid_lft forever preferred_lft forever
4: ens224: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether 00:50:56:80:09:b6 brd ff:ff:ff:ff:ff:ff
5: cali0f3d1e69ba2@if3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UP group default 
    link/ether ee:ee:ee:ee:ee:ee brd ff:ff:ff:ff:ff:ff link-netns cni-d9149877-330c-e816-c8c6-a0f1ba827ad4
    inet6 fe80::ecee:eeff:feee:eeee/64 scope link 
       valid_lft forever preferred_lft forever
6: flannel.1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UNKNOWN group default 
    link/ether ca:03:62:b0:74:f9 brd ff:ff:ff:ff:ff:ff
    inet 10.42.2.0/32 brd 10.42.2.0 scope global flannel.1
       valid_lft forever preferred_lft forever
    inet6 fe80::c803:62ff:feb0:74f9/64 scope link 
       valid_lft forever preferred_lft forever

[ChristianCiach]

I don't know if you can do this with Flannel, but you should look into Multus-CNI.

It's on the roadmap: https://github.com/k3s-io/k3s/blob/master/ROADMAP.md

Relevant issue: #4490

But until then, you can always disable Flannel and deploy Multus by yourself.