On Tue, Mar 12, 2019 at 11:10:40PM +0100, Lars Lindstrom wrote:
Hi everyone! I have the following requirement: I need to connect a set of Docker containers to a KVM. The containers shall be isolated in a way that they cannot communicate to each other without going through the KVM, which will act as router/firewall. For this, I thought about the following simple setup (as opposed to a more complex one involving a bridge with vlan_filtering and a seperate VLAN for each container): +------------------------------------------------------------------+ | Host | | +-------------+ +----------------------+---+ | | KVM | | Docker +-> | a | | | +----------+ +----------+ +--------------+ +---+ | | | NIC lan0 | <-> | DEV tap0 | <-> | NET macvlan0 | <-+-> | b | | | +----------+ +----------+ +--------------+ +---+ | | | | +-> | c | | +-------------+ +----------------------+---+ | | +------------------------------------------------------------------+ NIC lan0: <interface type='direct'> <source dev='tap0' mode='vepa'/> <model type='virtio'/> </interface> *** Welcome to pfSense 2.4.4-RELEASE-p1 (amd64) on pfSense *** LAN (lan) -> vtnet0 -> v4: 10.0.20.1/24 DEV tap0: [root@server ~]# ip tuntap add tap0 mode tap [root@server ~]# ip l set tap0 up [root@server ~]# ip l show tap0 49: tap0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel state DOWN mode DEFAULT group default qlen 1000 link/ether ce:9e:95:89:33:5f brd ff:ff:ff:ff:ff:ff [root@server ~]# virsh start pfsense [root@server opt]# ip l show tap0 49: tap0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel state DOWN mode DEFAULT group default qlen 1000 link/ether ce:9e:95:89:33:5f brd ff:ff:ff:ff:ff:ff
IIUC, you are using the tap0 device, but it is not plugged anywhere. By that I mean there is one end that you created and passed through into the VM, but there is no other end of that. I can think of some complicated ways how to do what you are trying to, but hopefully the above explanation will move you forward and you'll figure out something better than what I'm thinking about right now. What usually helps me is to think of a way this would be done with hardware and replicate that as most of the technology is modelled after HW anyway. Or someone else will have a better idea. Before sending it I just thought, wouldn't it be possible to just have a veth pair instead of the tap device? one end would go to the VM and the other one would be used for the containers' macvtaps...
NET macvlan0: [root@server ~]# docker network create --driver macvlan --subnet=10.0.20.0/24 --gateway=10.0.20.1 --opt parent=tap0 macvlan0 CNT a: [root@server ~]# docker run --network macvlan0 --ip=10.0.20.2 -it alpine /bin/sh / # ping -c 4 10.0.20.1 PING 10.0.20.1 (10.0.20.1): 56 data bytes --- 10.0.20.1 ping statistics --- 4 packets transmitted, 0 packets received, 100% packet loss / # ifconfig eth0 Link encap:Ethernet HWaddr 02:42:0A:00:14:02 inet addr:10.0.20.2 Bcast:10.0.20.255 Mask:255.255.255.0 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:4 errors:0 dropped:0 overruns:0 frame:0 TX packets:4 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:448 (448.0 B) TX bytes:448 (448.0 B) / # ip r default via 10.0.20.1 dev eth0 10.0.20.0/24 dev eth0 scope link src 10.0.20.2 CNT b: [root@server ~]# docker run --network macvlan0 --ip=10.0.20.2 -it alpine /bin/ping 10.0.20.1 PING 10.0.20.1 (10.0.20.1): 56 data bytes CNT c: [root@server ~]# docker run --network macvlan0 --ip=10.0.20.2 -it alpine /bin/ping 10.0.20.1 PING 10.0.20.1 (10.0.20.1): 56 data bytes The KVM is not reachable from within a Docker container (during the test firewalld was disabled) and vice versa. The first thing I noticed is that tap0 remains NO-CARRIER and DOWN, even though the KVM has been started. Shouldn't the link come up as soon as the KVM is started (and thus is connected to the tap0 device)? The next thing that looked strange to me - even though interface and routing configuration within the container seemingly looks OK, there are 0 packets TX/RX on eth0 after pinging the KVM (but 4 on lo instead). Any idea on how to proceed from here? Is this a valid setup and a valid libvirt configuration for that setup? Thanks and br, Lars _______________________________________________ libvirt-users mailing list libvirt-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvirt-users
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