CNAMEs for docker containers ?

[nklamann]

Hello all,
i have some Docker containers running in a virtual server in the cloud. Because I have only 1 IPv4 I built a proxy to access these containers under different names (CNAMES) .

This works fine but I would like to model the whole affair in netbox. I created a device for the virtual server and assigned the given IP. I have no doubt (didn't try yet) that i can generate the A and AAAA records just fine. But of course i can assign once and not to the containers living there.

So these containers cant' have IP adresses but should be visible as candidates for CNAMEs pointing to the address of the virtual server.

So it must be modeled that several cnames point to one ip address.

Is this possibe at all ?

[peteeckel]

Hi @nklamann, I think the main issue is the question you already posted in the Slack forum: How to best model containers in NetBox?

I'm not that much of a container guy, but for me containers are not much different from virtual machines in their setup. You basically have a device that hosts them (which is the physical host the containers are running on), and the containers as virtual machines running on the device. That's basically what you did.

Now the question is what you want to achieve in terms of DNS.

There's IPAM DNSsync as a means to synchronise IPAM IPAddress entities to DNS, but as a matter of fact (because you can only assign one "DNS name" to an IPAddress object within IPAM) that gives you exactly one A or AAAA record per IP address. Furthermore, you can't assign the same IPAddress object to multiple (virtual)interfaces, so that won't help you either. And actually - as far as I understand you - that's not the way it is actually set up, as the IP is on the device in reality and the proxy does the distribution to the containers, which have different IPs. That, however, does not help you much with DNS.

There are two approaches:

1. (Manually) define an address record for each container
2. Manually or automatically (IPAM DNSsync) create an address record for the physical IP address and define a CNAME for each container pointing to that name.

Both approaches will work. They differ in that if you are automatically creating PTR records, you will get one for each virtual interface's name with the first, and only one for the physical interface's address with the second approach. When you change the IP address on the device interface level, the second approach requires no further steps while for the first you need to do it for each container.

[peteeckel]

tl;dr: You can use automatic assignment of only one name per IP address, but you're entirely free with CNAMEs and multiple address records.