Source Endpoints de-duplication (dedupSource) performed before AdjustEndpoints

[krasoffski]

What happened:
Controller RunOnce get Records and than Source Endpoints.
After this, it performs AdjustEndpoints for Source Endpoints.

Here is simplified part.

func (c *Controller) RunOnce(ctx context.Context) error {
	lastReconcileTimestamp.SetToCurrentTime()

	records, err := c.Registry.Records(ctx)
	if err != nil {
		registryErrorsTotal.Inc()
		deprecatedRegistryErrors.Inc()
		return err
	}
	ctx = context.WithValue(ctx, provider.RecordsContextKey, records)

	endpoints, err := c.Source.Endpoints(ctx)
	if err != nil {
		return err
	}
	endpoints, err = c.Registry.AdjustEndpoints(endpoints)
	if err != nil {
		return fmt.Errorf("adjusting endpoints: %w", err)
	}
	registryFilter := c.Registry.GetDomainFilter()

}

During getting Source Endpoints: endpoints, err := c.Source.Endpoints(ctx) also performed de-duplication based on following attributes: DNSName, Targets and SetIdentifier.

Here is de-duplication simplified code:

for _, ep := range endpoints {
	identifier := ep.DNSName + " / " + ep.SetIdentifier + " / " + ep.Targets.String()

	if _, ok := collected[identifier]; ok {
		log.Debugf("Removing duplicate endpoint %s", ep)
		continue
	}

	collected[identifier] = true
	result = append(result, ep)
}

Thus, some Source Endpoints from sources are deleted before they are updated by AdjustEndpoints.
This leads to unexpected deletion de-duplicated records from DNS because they are de-deplicated before call AdjustEndpoints.
For example, SetIdentifier can be set or updated via AdjustEndpoints call to provider, after this Source Endpoint can became unique but has been de-duplicated before.

Or vice-versa case, provider can change SetIdentifier and Endpoint after AdjustEndpoints will be (should be) de-duplicated.

Finally, changed SetIdentifier used in planKey which with looks like a broken logic when we might perform de-duplication using different SetIdentifier value.

What you expected to happen:
I expect that Source Endpoints de-duplication performed after AdjustEndpoints call.

How to reproduce it (as minimally and precisely as possible):
It is clear from code.

Environment:

• External-DNS version: v0.14.1
• DNS provider: custom

BTW, I know there is annotation for setting SetIdentifier property, but it not solve this logic with AdjustEndpoints.