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kubernetes: add multicluster support (#7266)
* kubernetes: add multicluster support Add multicluster support via Multi-Cluster Services API (MCS-API) via a new option `multiclusterZones` in the kubernetes plugin. When some multicluster zones are passed to the kubernetes plugin, it will start watching the ServiceImport objects and its associated EndpointSlices. Signed-off-by: Arthur Outhenin-Chalandre <arthur@cri.epita.fr> * kubernetes: implement xfr support for multicluster zones Signed-off-by: Arthur Outhenin-Chalandre <arthur@cri.epita.fr> --------- Signed-off-by: Arthur Outhenin-Chalandre <arthur@cri.epita.fr>
This commit is contained in:
Arthur Outhenin-Chalandre
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GitHub
GitHub
parent
76b199f829
commit
5c71bd0b87
@@ -29,9 +29,7 @@ func (k *Kubernetes) Transfer(zone string, serial uint32) (<-chan []dns.RR, erro
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}
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ch := make(chan []dns.RR)
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zonePath := msg.Path(zone, "coredns")
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serviceList := k.APIConn.ServiceList()
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go func() {
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// ixfr fallback
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@@ -41,7 +39,6 @@ func (k *Kubernetes) Transfer(zone string, serial uint32) (<-chan []dns.RR, erro
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return
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}
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ch <- soa
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nsAddrs := k.nsAddrs(false, false, zone)
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nsHosts := make(map[string]struct{})
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for _, nsAddr := range nsAddrs {
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@@ -51,98 +48,191 @@ func (k *Kubernetes) Transfer(zone string, serial uint32) (<-chan []dns.RR, erro
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ch <- []dns.RR{&dns.NS{Hdr: dns.RR_Header{Name: zone, Rrtype: dns.TypeNS, Class: dns.ClassINET, Ttl: k.ttl}, Ns: nsHost}}
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}
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ch <- nsAddrs
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}
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sort.Slice(serviceList, func(i, j int) bool {
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return serviceList[i].Name < serviceList[j].Name
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})
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for _, svc := range serviceList {
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if !k.namespaceExposed(svc.Namespace) {
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continue
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if !k.isMultiClusterZone(zone) {
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k.transferServices(ch, zonePath)
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} else {
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k.transferMultiClusterServices(ch, zonePath)
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}
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svcBase := []string{zonePath, Svc, svc.Namespace, svc.Name}
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switch svc.Type {
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case api.ServiceTypeClusterIP, api.ServiceTypeNodePort, api.ServiceTypeLoadBalancer:
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clusterIP := net.ParseIP(svc.ClusterIPs[0])
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if clusterIP != nil {
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var host string
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for _, ip := range svc.ClusterIPs {
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s := msg.Service{Host: ip, TTL: k.ttl}
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s.Key = strings.Join(svcBase, "/")
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// Change host from IP to Name for SRV records
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host = emitAddressRecord(ch, s)
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ch <- soa
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close(ch)
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}
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}()
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return ch, nil
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}
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func (k *Kubernetes) transferServices(ch chan []dns.RR, zonePath string) {
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serviceList := k.APIConn.ServiceList()
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sort.Slice(serviceList, func(i, j int) bool {
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return serviceList[i].Name < serviceList[j].Name
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})
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for _, svc := range serviceList {
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if !k.namespaceExposed(svc.Namespace) {
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continue
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}
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svcBase := []string{zonePath, Svc, svc.Namespace, svc.Name}
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switch svc.Type {
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case api.ServiceTypeClusterIP, api.ServiceTypeNodePort, api.ServiceTypeLoadBalancer:
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clusterIP := net.ParseIP(svc.ClusterIPs[0])
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if clusterIP != nil {
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var host string
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for _, ip := range svc.ClusterIPs {
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s := msg.Service{Host: ip, TTL: k.ttl}
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s.Key = strings.Join(svcBase, "/")
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// Change host from IP to Name for SRV records
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host = emitAddressRecord(ch, s)
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}
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for _, p := range svc.Ports {
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s := msg.Service{Host: host, Port: int(p.Port), TTL: k.ttl}
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s.Key = strings.Join(svcBase, "/")
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// Need to generate this to handle use cases for peer-finder
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// ref: https://github.com/coredns/coredns/pull/823
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ch <- []dns.RR{s.NewSRV(msg.Domain(s.Key), 100)}
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// As per spec unnamed ports do not have a srv record
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// https://github.com/kubernetes/dns/blob/master/docs/specification.md#232---srv-records
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if p.Name == "" {
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continue
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}
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for _, p := range svc.Ports {
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s := msg.Service{Host: host, Port: int(p.Port), TTL: k.ttl}
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s.Key = strings.Join(append(svcBase, strings.ToLower("_"+string(p.Protocol)), strings.ToLower("_"+p.Name)), "/")
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ch <- []dns.RR{s.NewSRV(msg.Domain(s.Key), 100)}
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}
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// Skip endpoint discovery if clusterIP is defined
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continue
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}
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endpointsList := k.APIConn.EpIndex(svc.Name + "." + svc.Namespace)
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for _, ep := range endpointsList {
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for _, eps := range ep.Subsets {
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srvWeight := calcSRVWeight(len(eps.Addresses))
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for _, addr := range eps.Addresses {
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s := msg.Service{Host: addr.IP, TTL: k.ttl}
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s.Key = strings.Join(svcBase, "/")
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// We don't need to change the msg.Service host from IP to Name yet
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// so disregard the return value here
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emitAddressRecord(ch, s)
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// Need to generate this to handle use cases for peer-finder
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// ref: https://github.com/coredns/coredns/pull/823
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ch <- []dns.RR{s.NewSRV(msg.Domain(s.Key), 100)}
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s.Key = strings.Join(append(svcBase, endpointHostname(addr, k.endpointNameMode)), "/")
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// Change host from IP to Name for SRV records
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host := emitAddressRecord(ch, s)
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s.Host = host
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for _, p := range eps.Ports {
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// As per spec unnamed ports do not have a srv record
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// https://github.com/kubernetes/dns/blob/master/docs/specification.md#232---srv-records
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if p.Name == "" {
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continue
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}
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s.Port = int(p.Port)
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s.Key = strings.Join(append(svcBase, strings.ToLower("_"+p.Protocol), strings.ToLower("_"+p.Name)), "/")
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ch <- []dns.RR{s.NewSRV(msg.Domain(s.Key), srvWeight)}
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}
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}
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}
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}
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case api.ServiceTypeExternalName:
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s := msg.Service{Key: strings.Join(svcBase, "/"), Host: svc.ExternalName, TTL: k.ttl}
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if t, _ := s.HostType(); t == dns.TypeCNAME {
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ch <- []dns.RR{s.NewCNAME(msg.Domain(s.Key), s.Host)}
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}
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}
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}
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}
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func (k *Kubernetes) transferMultiClusterServices(ch chan []dns.RR, zonePath string) {
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serviceImportList := k.APIConn.ServiceImportList()
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sort.Slice(serviceImportList, func(i, j int) bool {
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return serviceImportList[i].Name < serviceImportList[j].Name
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})
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for _, svcImport := range serviceImportList {
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if !k.namespaceExposed(svcImport.Namespace) {
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continue
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}
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svcBase := []string{zonePath, Svc, svcImport.Namespace, svcImport.Name}
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var clusterIP net.IP
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if len(svcImport.ClusterIPs) > 0 {
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clusterIP = net.ParseIP(svcImport.ClusterIPs[0])
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}
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if clusterIP != nil {
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var host string
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for _, ip := range svcImport.ClusterIPs {
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s := msg.Service{Host: ip, TTL: k.ttl}
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s.Key = strings.Join(svcBase, "/")
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// Change host from IP to Name for SRV records
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host = emitAddressRecord(ch, s)
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}
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for _, p := range svcImport.Ports {
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s := msg.Service{Host: host, Port: int(p.Port), TTL: k.ttl}
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s.Key = strings.Join(svcBase, "/")
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// Need to generate this to handle use cases for peer-finder
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// ref: https://github.com/coredns/coredns/pull/823
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ch <- []dns.RR{s.NewSRV(msg.Domain(s.Key), 100)}
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// As per spec unnamed ports do not have a srv record
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// https://github.com/kubernetes/dns/blob/master/docs/specification.md#232---srv-records
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if p.Name == "" {
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continue
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}
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s.Key = strings.Join(append(svcBase, strings.ToLower("_"+string(p.Protocol)), strings.ToLower("_"+p.Name)), "/")
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ch <- []dns.RR{s.NewSRV(msg.Domain(s.Key), 100)}
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}
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// Skip endpoint discovery if clusterIP is defined
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continue
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}
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endpointsList := k.APIConn.McEpIndex(svcImport.Name + "." + svcImport.Namespace)
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for _, ep := range endpointsList {
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for _, eps := range ep.Subsets {
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srvWeight := calcSRVWeight(len(eps.Addresses))
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for _, addr := range eps.Addresses {
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s := msg.Service{Host: addr.IP, TTL: k.ttl}
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s.Key = strings.Join(svcBase, "/")
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// We don't need to change the msg.Service host from IP to Name yet
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// so disregard the return value here
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emitAddressRecord(ch, s)
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s.Key = strings.Join(append(svcBase, endpointHostname(addr, k.endpointNameMode)), "/")
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// Change host from IP to Name for SRV records
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host := emitAddressRecord(ch, s)
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s.Host = host
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for _, p := range eps.Ports {
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// As per spec unnamed ports do not have a srv record
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// https://github.com/kubernetes/dns/blob/master/docs/specification.md#232---srv-records
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if p.Name == "" {
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continue
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}
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s.Key = strings.Join(append(svcBase, strings.ToLower("_"+string(p.Protocol)), strings.ToLower("_"+p.Name)), "/")
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s.Port = int(p.Port)
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ch <- []dns.RR{s.NewSRV(msg.Domain(s.Key), 100)}
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s.Key = strings.Join(append(svcBase, strings.ToLower("_"+p.Protocol), strings.ToLower("_"+p.Name)), "/")
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ch <- []dns.RR{s.NewSRV(msg.Domain(s.Key), srvWeight)}
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}
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// Skip endpoint discovery if clusterIP is defined
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continue
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}
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endpointsList := k.APIConn.EpIndex(svc.Name + "." + svc.Namespace)
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for _, ep := range endpointsList {
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for _, eps := range ep.Subsets {
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srvWeight := calcSRVWeight(len(eps.Addresses))
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for _, addr := range eps.Addresses {
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s := msg.Service{Host: addr.IP, TTL: k.ttl}
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s.Key = strings.Join(svcBase, "/")
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// We don't need to change the msg.Service host from IP to Name yet
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// so disregard the return value here
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emitAddressRecord(ch, s)
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s.Key = strings.Join(append(svcBase, endpointHostname(addr, k.endpointNameMode)), "/")
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// Change host from IP to Name for SRV records
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host := emitAddressRecord(ch, s)
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s.Host = host
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for _, p := range eps.Ports {
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// As per spec unnamed ports do not have a srv record
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// https://github.com/kubernetes/dns/blob/master/docs/specification.md#232---srv-records
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if p.Name == "" {
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continue
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}
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s.Port = int(p.Port)
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s.Key = strings.Join(append(svcBase, strings.ToLower("_"+p.Protocol), strings.ToLower("_"+p.Name)), "/")
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ch <- []dns.RR{s.NewSRV(msg.Domain(s.Key), srvWeight)}
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}
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}
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}
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}
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case api.ServiceTypeExternalName:
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s := msg.Service{Key: strings.Join(svcBase, "/"), Host: svc.ExternalName, TTL: k.ttl}
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if t, _ := s.HostType(); t == dns.TypeCNAME {
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ch <- []dns.RR{s.NewCNAME(msg.Domain(s.Key), s.Host)}
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}
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}
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}
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ch <- soa
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close(ch)
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}()
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return ch, nil
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}
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}
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// emitAddressRecord generates a new A or AAAA record based on the msg.Service and writes it to a channel.
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