Support multi-value A-records

[r35krag0th]

Feature Description

I'm not sure if this is intentional or not (limitations of UniFi's API), but currently any multi-value A-records will only write the first value to the UniFi DNS API.

The Istio Ingress GW has 3 External IPs.

kubectl get svc/istio-ingressgateway -n istio-system

NAME                   TYPE        CLUSTER-IP    EXTERNAL-IP                           PORT(S)                    AGE
istio-ingressgateway   ClusterIP   10.43.45.47   10.0.43.221,10.0.43.231,10.0.43.241   15021/TCP,80/TCP,443/TCP   140d

But only the first one gets written.

# Checking what was written
dig @10.0.42.1 api.dev.r35.network
10.0.43.221

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[kashalls]

This is a known issue, at least for me: https://github.com/kashalls/external-dns-unifi-webhook/blob/main/internal/unifi/client.go#L221

UniFi only supports creating 1:1 records. I need a way to match up 1:* without making it super complicated (as external-dns can have many targets as possible)

When ExternalDNS calls GetRecords, it is going to want to match the state of the cluster itself. I'm open to ideas on how to do this.

[r35krag0th]

I do know you can have multiple A records with the same name (left hand value) in UniFi DNS.

I need to sit down and learn more about the implementation to really have a good grasp. I'm definitely highly invested in getting this to work.

[kashalls]

I need to sit down and learn more about the implementation to really have a good grasp. I'm definitely highly invested in getting this to work.

I made #94 to build a "test". When it's finished building that image, can you test the tag pr-94 and see if by chance that works? Sorry about the experimentation 😺

[kashalls]

Here's an image to test: ghcr.io/kashalls/external-dns-unifi-webhook:pr-94

[r35krag0th]

I can confirm that does in fact create the additional records correctly. Looks like a good fix to me.

I'll create another ticket for better handling reconciliation (using sync policy) where the behavior seems to be:

1. delete all records that match discovered endpoints
2. delete all registry records
3. create all records with current data
4. create all registry records

[kashalls]

I can confirm that does in fact create the additional records correctly. Looks like a good fix to me.

Does external-dns seem to endlessly sync instead of occuring once and just idling?

[r35krag0th]

I can confirm that does in fact create the additional records correctly. Looks like a good fix to me.

Does external-dns seem to endlessly sync instead of occuring once and just idling?

It does run once and pause for the next interval.

Logs

external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668586.6443675,"caller":"unifi/provider.go:67","msg":"deleting endpoint","name":"api.dev.r35.network","type":"A"}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668586.6740441,"caller":"unifi/client.go:283","msg":"Client deleted record","record":{"_id":"67c07e71d7ba2a44bdc7e5dc","enabled":true,"key":"api.dev.r35.network","port":0,"priority":0,"record_type":"A","value":"10.0.43.221","weight":0}}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668586.685423,"caller":"unifi/client.go:283","msg":"Client deleted record","record":{"_id":"67c07e71d7ba2a44bdc7e5de","enabled":true,"key":"api.dev.r35.network","port":0,"priority":0,"record_type":"A","value":"10.0.43.231","weight":0}}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668586.6964533,"caller":"unifi/client.go:283","msg":"Client deleted record","record":{"_id":"67c07e71d7ba2a44bdc7e5e0","enabled":true,"key":"api.dev.r35.network","port":0,"priority":0,"record_type":"A","value":"10.0.43.241","weight":0}}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668588.3212514,"caller":"unifi/provider.go:67","msg":"deleting endpoint","name":"k8s.api.dev.r35.network","type":"TXT"}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668588.3508084,"caller":"unifi/client.go:283","msg":"Client deleted record","record":{"_id":"67c07e73d7ba2a44bdc7e670","enabled":true,"key":"k8s.api.dev.r35.network","port":0,"priority":0,"record_type":"TXT","value":"\"heritage=external-dns,external-dns/owner=rke2,external-dns/resource=gateway/istio-system/r35-api-dev-gateway\"","weight":0}}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668588.3508756,"caller":"unifi/provider.go:67","msg":"deleting endpoint","name":"k8s.a-api.dev.r35.network","type":"TXT"}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668588.3787184,"caller":"unifi/client.go:283","msg":"Client deleted record","record":{"_id":"67c07e73d7ba2a44bdc7e672","enabled":true,"key":"k8s.a-api.dev.r35.network","port":0,"priority":0,"record_type":"TXT","value":"\"heritage=external-dns,external-dns/owner=rke2,external-dns/resource=gateway/istio-system/r35-api-dev-gateway\"","weight":0}}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668589.8568807,"caller":"unifi/provider.go:76","msg":"creating endpoint","name":"api.dev.r35.network","type":"A"}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668589.8725803,"caller":"unifi/client.go:257","msg":"client created new record","record":{"_id":"67c07eadd7ba2a44bdc7e77c","enabled":true,"key":"api.dev.r35.network","port":0,"priority":0,"record_type":"A","value":"10.0.43.221","weight":0}}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668589.8858943,"caller":"unifi/client.go:257","msg":"client created new record","record":{"_id":"67c07eadd7ba2a44bdc7e77e","enabled":true,"key":"api.dev.r35.network","port":0,"priority":0,"record_type":"A","value":"10.0.43.231","weight":0}}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668589.9016798,"caller":"unifi/client.go:257","msg":"client created new record","record":{"_id":"67c07eadd7ba2a44bdc7e780","enabled":true,"key":"api.dev.r35.network","port":0,"priority":0,"record_type":"A","value":"10.0.43.241","weight":0}}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668591.1220295,"caller":"unifi/provider.go:76","msg":"creating endpoint","name":"k8s.api.dev.r35.network","type":"TXT"}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668591.1358945,"caller":"unifi/client.go:257","msg":"client created new record","record":{"_id":"67c07eafd7ba2a44bdc7e814","enabled":true,"key":"k8s.api.dev.r35.network","port":0,"priority":0,"record_type":"TXT","value":"\"heritage=external-dns,external-dns/owner=rke2,external-dns/resource=gateway/istio-system/r35-api-dev-gateway\"","weight":0}}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668591.135968,"caller":"unifi/provider.go:76","msg":"creating endpoint","name":"k8s.a-api.dev.r35.network","type":"TXT"}
external-dns-unifi-7f75c99dbf-4plth webhook {"level":"debug","ts":1740668591.1497874,"caller":"unifi/client.go:257","msg":"client created new record","record":{"_id":"67c07eafd7ba2a44bdc7e816","enabled":true,"key":"k8s.a-api.dev.r35.network","port":0,"priority":0,"record_type":"TXT","value":"\"heritage=external-dns,external-dns/owner=rke2,external-dns/resource=gateway/istio-system/r35-api-dev-gateway\"","weight":0}}

Summarized

1. deletes endpoint api.dev.r35.network
   1. delete 10.0.43.221
   2. delete 10.0.43.231
   3. delete 10.0.43.241
2. delete endpoints for registry records
   1. delete registry record k8s.api.dev.r35.network
   2. delete registry record k8s.a-api.dev.r35.network2. create endpoint and records (A)
3. create endpoint api.dev.r35.network
   1. create 10.0.43.221
   2. create 10.0.43.231
   3. create 10.0.43.241
4. create endpoints for registry records
   1. create registry record k8s.api.dev.r35.network
   2. create registry record k8s.a-api.dev.r35.network

[kashalls]

Does external-dns seem to endlessly sync instead of occuring once and just idling?

It does run once and pause for the next interval.

I just checked and this implementation allows for the records to be created and deleted. However, the GetEndpoints is still returning the wrong response to ExternalDNS causing the records to be constantly updated (by being deleted and created every time it sync's) when I create three kubernetes secrets with different external ips and identical hostnames. It would not be a good idea for this to be pushed to main as is IMO.

Not against the idea of supporting this, just no known way to fix this.