no default gateway on OCI container with dhcp

[komacke]

I'm trying out the new OCI image feature. It's very cool!

I use DHCP to manage IP addresses across services from the network. When I launch turnkeylinux templates, IP addressing works fine.

I've tried launching the nginx:latest image from docker hub. It gets an IP address but does not get a gateway. It is not accessible from outside the subnet. It is accessible from within the subnet.

If I assign it a static IP address and gateway, the container is accessible outside the subnet.

I've verified the missing gateway by using lxc-attach, installing iproute2 package, and checking 'ip route'. The gateway is missing. If I manually add the gateway with " ip route add def via <gateway ip address>" then connectivity is enabled and the container is accessible. (Note: to install the ip route package, I had to temporarily assign a static ip address/gateway so the container could get internet connectivity.)

I believe I need to enable "Host-Managed" since the container does not have a dhcp-client. Is this perhaps a difference between turnkeylinux templates? They seem to have udhcpc in them, so maybe this points to the issue.

Dave

 

[fschauer]

I believe I need to enable "Host-Managed" since the container does not have a dhcp-client. Is this perhaps a difference between turnkeylinux templates? They seem to have udhcpc in them, so maybe this points to the issue.

Yes, "host-managed" needs to be enabled, when the container does not run its own internal DHCP client on that network interface.

 

[komacke]

Sounds good. However the issue remains. No default route is assigned to the container in host-managed mode.

Is this a bug with the new OCI support?

 

[fschauer]

Are you using IPv4 or IPv6?
Proxmox VE still uses isc-dhcp-client for host-managed interfaces, while turnkeylinux templates use udhcpc as their DHCP client. These two clients behave slightly differently.

Could you please test with the debian-13-standard LXC template? It also uses isc-dhcp-client, so it will show whether the gateway issue appears on regular system containers as well.

 

[komacke]

Hi Filip

This is ipv4 on an OCI-based container. I used the docker ngnix:latest image. It does not have a dhcp client installed so host-managed is necessary (which you confirmed)

The IP address gets set as provided by my external dhcp server. However the default gateway does not get set.

I only mentioned turnkey templates above to confirm they work fine with my external dhcp server, suggesting it is not a problem with my dhcp server. As you request I've tried it with the Debian lxc template and udhcp works fine.

I think proxmox has a bug with OCI images and host-managed set using dhcp where the default gateway does not get set in the container.

Dave