CoreDNS Provider: ETCD datastore version

[muffin87]

Hi everyone,

I did some experiments with external-dns and CoreDNS.
I'm running Kubernetes On-Prem and want a dynamic DNS server which holds the records for all Services from the type: LoadBalancer and Ingress Objects. The idea was to delegate a sub domain to the this dynamic DNS server.

So I started external-dns with the provider CoreDNS:

Frist thing I notice was that I need a ETCD cluster. So I added a single node ETCD cluster into the same POD. With that in place external-dns pushes key values pairs into ETCD. Next step was to integrate CoreDNS. I added CoreDNS to the Pod and tried to query the A records external-dns pushed. And I saw nothing.

I jumped into debugging and found out that external-dns pushes into etcdv2 datastore and CoreDNS tried to read from etcdv3 datastore. I migrated the etcdv2 datastore to v3 and after that CoreDNS gives me the answers i expcted.

So my question is did I miss something? Is there a config parameter somewhere where I can specify the etcd datastore version? Or is my setup wrong?

external-dns config:

 args:
    - --source=service
    - --source=ingress
    - --provider=coredns
    - --policy=sync
    - --registry=txt
    - --log-format=text
    - --log-level=debug
    - --metrics-address=:7979

CoreDNS config:

  - args:
    - -conf
    - /etc/coredns/Corefile
    - -dns.port
    - "10053"

Corefile: |-
    .:10053 {
      cache 30
      errors
      etcd example.com {
        path /skydns
        endpoint http://localhost:2379
      }
      health
      loadbalance round_robin
      log
      prometheus 0.0.0.0:9153
    }

[shashidharatd]

The CoreDNS provider in external-dns does work with etcd v2 client. it needs to migrate to use etcd v3 client, as recent version of CoreDNS etcd plugin migrated to etcd v3.

[shashidharatd]

The workaround could be to use older version of CoreDNS server

[muffin87]

@shashidharatd thanks for your response. That clarifies why external-dns is using etcd v2 client. As a workaround I'm currently using SkyDNS. I will also try to use an older version of CoreDNS.

Are there any plans to migrate the CoreDNS provider to etcd v3 in the near future?