TrueCloudLab/coredns
16
0
Fork 2
Code Issues Pull requests 1 Projects Releases Packages Wiki Activity Actions

plugin/k8s_external/kubernetes: handle NS records (#3160)

Browse source 
* fix external ns records

* use k8s service name for ns record

* update test, add func comment

* expand nsAddrs() test cases

* support local ipv6 ip

* use less confusing pod ip in test
This commit is contained in:
Chris O'Haver 2019-08-23 12:54:06 -04:00 • committed by Miek Gieben
parent 84988ce2c2
commit 338d148c78
6 changed files with 180 additions and 70 deletions
Download patch file Download diff file Expand all files Collapse all files

91
plugin/kubernetes/ns.go
View file

@ -4,6 +4,7 @@ import (
"net"
"strings"
"github.com/coredns/coredns/plugin/kubernetes/object"
"github.com/miekg/dns"
api "k8s.io/api/core/v1"
)
@ -12,54 +13,74 @@ func isDefaultNS(name, zone string) bool {
return strings.Index(name, defaultNSName) == 0 && strings.Index(name, zone) == len(defaultNSName)
}
// nsAddr return the A record for the CoreDNS service in the cluster. If it fails that it fallsback
// on the local address of the machine we're running on.
//
// This function is rather expensive to run.
func (k *Kubernetes) nsAddr() *dns.A {
// nsAddrs returns the A or AAAA records for the CoreDNS service in the cluster. If the service cannot be found,
// it returns a record for the the local address of the machine we're running on.
func (k *Kubernetes) nsAddrs(external bool, zone string) []dns.RR {
var (
svcName string
svcNamespace string
svcNames []string
svcIPs []net.IP
)
rr := new(dns.A)
// Find the CoreDNS Endpoint
localIP := k.interfaceAddrsFunc()
rr.A = localIP
endpoints := k.APIConn.EpIndexReverse(localIP.String())
FindEndpoint:
for _, ep := range k.APIConn.EpIndexReverse(localIP.String()) {
for _, eps := range ep.Subsets {
for _, addr := range eps.Addresses {
if localIP.Equal(net.ParseIP(addr.IP)) {
svcNamespace = ep.Namespace
svcName = ep.Name
break FindEndpoint
// If the CoreDNS Endpoint is not found, use the locally bound IP address
if len(endpoints) == 0 {
svcNames = []string{defaultNSName + zone}
svcIPs = []net.IP{localIP}
} else {
// Collect IPs for all Services of the Endpoints
for _, endpoint := range endpoints {
svcs := k.APIConn.SvcIndex(object.ServiceKey(endpoint.Name, endpoint.Namespace))
for _, svc := range svcs {
if external {
svcName := strings.Join([]string{svc.Name, svc.Namespace, zone}, ".")
for _, exIP := range svc.ExternalIPs {
svcNames = append(svcNames, svcName)
svcIPs = append(svcIPs, net.ParseIP(exIP))
}
continue
}
svcName := strings.Join([]string{svc.Name, svc.Namespace, Svc, zone}, ".")
if svc.ClusterIP == api.ClusterIPNone {
// For a headless service, use the endpoints IPs
for _, s := range endpoint.Subsets {
for _, a := range s.Addresses {
svcNames = append(svcNames, endpointHostname(a, k.endpointNameMode)+"."+svcName)
svcIPs = append(svcIPs, net.ParseIP(a.IP))
}
}
} else {
svcNames = append(svcNames, svcName)
svcIPs = append(svcIPs, net.ParseIP(svc.ClusterIP))
}
}
}
}
if len(svcName) == 0 {
rr.Hdr.Name = defaultNSName
rr.A = localIP
return rr
}
FindService:
for _, svc := range k.APIConn.ServiceList() {
if svcName == svc.Name && svcNamespace == svc.Namespace {
if svc.ClusterIP == api.ClusterIPNone {
rr.A = localIP
} else {
rr.A = net.ParseIP(svc.ClusterIP)
}
break FindService
// Create an RR slice of collected IPs
var rrs []dns.RR
rrs = make([]dns.RR, len(svcIPs))
for i, ip := range svcIPs {
if ip.To4() == nil {
rr := new(dns.AAAA)
rr.Hdr.Class = dns.ClassINET
rr.Hdr.Rrtype = dns.TypeAAAA
rr.Hdr.Name = svcNames[i]
rr.AAAA = ip
rrs[i] = rr
continue
}
rr := new(dns.A)
rr.Hdr.Class = dns.ClassINET
rr.Hdr.Rrtype = dns.TypeA
rr.Hdr.Name = svcNames[i]
rr.A = ip
rrs[i] = rr
}
rr.Hdr.Name = strings.Join([]string{svcName, svcNamespace, "svc."}, ".")
return rr
return rrs
}
const defaultNSName = "ns.dns."