Support Traefik ingress controller

[cknowles]

I'd like to support Traefik as the ingress controller. Could someone point me in the right direction? I found the following code which seems to indicate Traefik would need to be updating the ingress status. Is there more to it than that?

https://github.com/kubernetes-incubator/external-dns/blob/b23765ed2722c5b39961eb6cf51d094c2db02d6b/source/ingress.go#L221

[hjacobs]

Yes, ideally the ingress controller updates the status field. There is a known workaround for ingress controllers who don't do that, see https://github.com/kubernetes-incubator/external-dns/blob/master/docs/faq.md#are-other-ingress-controllers-supported

[cknowles]

@hjacobs thanks, we've started using that annotation for now. I checked the status of our ingresses and it seems Traefik is not updating them so perhaps I should move this issue to the Traefik repo. I couldn't find much in the way of kube docs around updating the status of an Ingress.

[caarlos0]

@c-knowles did you manage to get this working?

[cknowles]

@caarlos0 yeah, the instructions above work ok:

1. Set metadata.annotations['external-dns.alpha.kubernetes.io/hostname'] on the Service record for the Ingress controller to something like ingress.YOUR-DOMAIN
2. Wait for that to get actioned by external-dns so it creates the DNS record
3. Set metadata.annotations['external-dns.alpha.kubernetes.io/target'] on the Ingress to ingress.YOUR-DOMAIN

The key to getting it to work on Route 53 at least was #2. From what I remember external-dns attempts to batch the DNS updates so if #1 is not in place first then the batch contains #1 and #3 which fails and it will never complete.

[rafaelmagu]

Any chance we can get these three steps added to the documentation as a side-note when using Traefik?

I'm using Helm to deploy Traefik and added this to my values.yaml:

service:
  annotations:
    external-dns.alpha.kubernetes.io/hostname: ingress.example.com

[coderanger]

For others that find this, Traefik 1.7 now supports setting the required status fields. You'll have to set one of the [kubernetes.ingressEndpoint] settings in your config, such as:

[kubernetes.ingressEndpoint]
publishedService = "traefik/traefik"

See https://docs.traefik.io/v1.7/configuration/backends/kubernetes/#ingressendpoint for more details.

[dusansusic]

@coderanger i don't understand, does this mean that traefik 1.7 support external-dns? Thanks.

[coderanger]

Yes, with that setting turned on Traefik 1.7 supports external-dns.

[dusansusic]

@coderanger thanks for fast answer.

what does this setting do?
publishedService = "traefik/traefik"

[coderanger]

The ingress controller (traefik) needs to know what address to publish into DNS. You can either set a fixed IP or hostname, or set a service to copy the information from. The latter is the more common case, so that's setting the service to copy from to one named traefik in the namespace also named traefik. Or more generally you are specifying a service object in namespace/servicename format :)

[coderanger]

Are you use you're using 1.7? You don't need to change it every time you make a new Ingress, as your example shows the status publish uses the Service (usually a LoadBalancer service) in front of the Traefik pods themselves. First check that the Service has a hostname or IP in its status:

$  kubectl get service -n traefik traefik -o=json | jq .status
{
  "loadBalancer": {
    "ingress": [
      {
        "ip": "35.230.xx.xx"
      }
    ]
  }
}

Then check that Traefik is correctly copying that to the status of the Ingress:

$  kubectl get ingress -n zomg zomg-web -o json | jq .status
{
  "loadBalancer": {
    "ingress": [
      {
        "ip": "35.230.xx.xx"
      }
    ]
  }
}

The thing external-dns actually cares about is that Status field in the Ingress (or Service if publishing those) so if it's set, you should be golden.

[bradenwright]

FYI for anyone using helm you just need to set the following:

kubernetes:
  ingressEndpoint:
    useDefaultPublishedService: true

https://github.com/helm/charts/blob/master/stable/traefik/values.yaml#L51

[bradenwright]

@c-knowles @hjacobs I'd consider this issue closed, I guess maybe worth updating documentation but its definitely supported and very easy to get working

[hjacobs]

@bradenwright let's have 1-2 sentences about it in the FAQ. I guess a new bullet item here makes sense: "Traefik is supported when setting the XYZ flag"

[coderanger]

How about this:

• Traefik, when kubernetes.ingressEndpoint is configured(kubernetes.ingressEndpoint.useDefaultPublishedService in the Helm chart)

[hjacobs]

PR welcome 😄

[cknowles]

I can confirm this is working with the latest chart for Traefik and the above settings, we upgraded to that a couple of weeks ago and it's now setting the Ingress statuses which then gets picked up by external-dns automatically.

[mostrovoi]

How do you guys configure traefik to make this config work? I am not using helm so I created a configmap containing the following:
apiVersion: v1 kind: ConfigMap metadata: name: traefik-configmap namespace: ingress-sc data: traefik.toml: | [kubernetes] [kubernetes.ingressEndpoint] publishedService = "ingress-sc/traefik-ingress-service"
In the deployment section I set configfile pointing to the volume containing this configmap. I dont set --api neither --kubernetes as args since I read somewhere that if I set a configfile these will overwrite my configfile.
Could you guys provide a valid snippet to make this work?
Thanks!

[coderanger]

@mostrovoi Explaining how to configure Traefik in general is out of scope for this ticket. Please ask on one of the various Slack channels or other support systems for Traefik.