bryantluk
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bryantluk

How to change DNS nameserver for CoreOS?

September 19, 2014 4.4k views

Hi,

I'm using the CoreOS image for my droplet. Is there any way to change which DNS name server is used? I would actually like to use consul.io for service lookup and have it fallback to the Google DNS servers.

1 Answer

On CoreOS, /etc/resolve.conf is managed by systemd. One way to append to it would be to use the cloud-config metadata to add a new systemd unit file. Something like:

#cloud-config
coreos:
  etcd:
    # generate a new token for each unique cluster from https://discovery.etcd.io/new
    discovery: https://discovery.etcd.io/[your-token-here]
    # multi-region deployments, multi-cloud deployments, and droplets without
    # private networking need to use $public_ipv4
    addr: $private_ipv4:4001
    peer-addr: $private_ipv4:7001
  fleet:
    public-ip: $private_ipv4   # used for fleetctl ssh command
  units:
    - name: etcd.service
      command: start
    - name: fleet.service
      command: start
      units:
    - name: nameservers.network
      content: |
        [Network]
        DNS=8.8.4.4
        DNS=8.8.8.8
  • Thanks. While I can append entries to the nameservers list, I don't think it guarantees usage. I guess I would really like to replace the nameservers used entirely.

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