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plugin/k8s_external: Add support for PTR requests (#5435)

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* Exclude External IP addresses from being added to the existing kubernetes' plugin IP->Service index
* Add support for PTR requests on External IPs of Services to the k8s_external plugin

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>
This commit is contained in:
Chris O'Haver 2022-07-06 13:55:15 -04:00 • committed by GitHub
parent d903a963ee
commit e80d696502
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GPG key ID: 4AEE18F83AFDEB23
12 changed files with 163 additions and 44 deletions
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37
plugin/kubernetes/external.go
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@ -14,6 +14,18 @@ import (
// External implements the ExternalFunc call from the external plugin.
// It returns any services matching in the services' ExternalIPs.
func (k *Kubernetes) External(state request.Request) ([]msg.Service, int) {
if state.QType() == dns.TypePTR {
ip := dnsutil.ExtractAddressFromReverse(state.Name())
if ip != "" {
svcs, err := k.ExternalReverse(ip)
if err != nil {
return nil, dns.RcodeNameError
}
return svcs, dns.RcodeSuccess
}
// for invalid reverse names, fall through to determine proper nxdomain/nodata response
}
base, _ := dnsutil.TrimZone(state.Name(), state.Zone)
segs := dns.SplitDomainName(base)
@ -76,6 +88,10 @@ func (k *Kubernetes) External(state request.Request) ([]msg.Service, int) {
}
}
}
if state.QType() == dns.TypePTR {
// if this was a PTR request, return empty service list, but retain rcode for proper nxdomain/nodata response
return nil, rcode
}
return services, rcode
}
@ -111,3 +127,24 @@ func (k *Kubernetes) ExternalServices(zone string) (services []msg.Service) {
func (k *Kubernetes) ExternalSerial(string) uint32 {
return uint32(k.APIConn.Modified(true))
}
// ExternalReverse does a reverse lookup for the external IPs
func (k *Kubernetes) ExternalReverse(ip string) ([]msg.Service, error) {
records := k.serviceRecordForExternalIP(ip)
if len(records) == 0 {
return records, errNoItems
}
return records, nil
}
func (k *Kubernetes) serviceRecordForExternalIP(ip string) []msg.Service {
var svcs []msg.Service
for _, service := range k.APIConn.SvcExtIndexReverse(ip) {
if len(k.Namespaces) > 0 && !k.namespaceExposed(service.Namespace) {
continue
}
domain := strings.Join([]string{service.Name, service.Namespace}, ".")
svcs = append(svcs, msg.Service{Host: domain, TTL: k.ttl})
}
return svcs
}