RancherOS 1.4.2 install adding duplicate entries to DNS?


#1

Hello,

I am doing a sanity check before I open a support case… is it the case that cloud-config will make changes to the DNS service somehow? The cloud config docs seem to imply that yes this is possible, at least the way it’s worded.

After each ROS install we are seeing some odd entries, in some cases causing disruption to existing names (such as “rancher.mycompany.org” loses the IP we assigned to it after suspected rancheros install).

Is there any way to stop rancheros install from making changes to DNS?

Or is this impossible and therefore something in our current environment we are confused about?

Cloud config DNS section:

rancher:
  network:
   dns:
     domain:
     - mycompany.org
     nameservers:
     - x.x.x.x
     - x.x.x.x
     search:
     - mycompany.org

Thanks!


#2

By default RancherOS will uses domain_name_servers as DNS info which is fetched from DHCP server.
User can prevent this dynamic fetching behavior by setting up fixed DNS info, such as:

#cloud-config
rancher:
  network:
    dns:
      nameservers:
      - 8.8.8.8
      - 8.8.4.4
      search:
      - rancher.com

#3

This was resolved, the problem was partially on our end. The DNS had auto-register checkbox checked somewhere. The admin turned it off. What we were seeing was the IP of our Rancher server being changed to a random IP after any install of ROS. So the name “rancher” was being added into DNS with a random IP for every rancheros install (at initial boot into memory).


#4

Well the solution failed the next time we tried to install another ros machine. Some kind of limited scope DNS setting did not prevent RancherOS when it boot into memory from going out to DNS and blowing away the IP for rancher.mycompany.com

lol it’s funny we go to the trouble to have HA and a multi-node cluster, and because of our DNS name we create an integrated system with a single point of failure which blows away the API for everybody in the system including the web interface.

What about, let’s not have an integrated system anymore… :rofl:


#5

ended up changing the name to rancher-server.mycompany.com

“rancher” is a target that will change IP with even every reboot of any rancheros host, I think if launched on vmware integrated with on-prem IT (this didn’t happen on kvm nodes).

you don’t want your all-important API changing IP addresses at random.

I was thinking until today that I wanted a real OS instead, but just read what redhat did with RHEL 8 not supporting docker and selling podman, buildah, instead, they must be kidding…enough already… I’ll stick with RancherOS there are no more real OSes…