60 lines
2.1 KiB
Go
60 lines
2.1 KiB
Go
package kubernetes
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import (
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"context"
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"strings"
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"github.com/coredns/coredns/plugin"
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"github.com/coredns/coredns/plugin/etcd/msg"
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"github.com/coredns/coredns/plugin/pkg/dnsutil"
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"github.com/coredns/coredns/request"
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)
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// Reverse implements the ServiceBackend interface.
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func (k *Kubernetes) Reverse(ctx context.Context, state request.Request, exact bool, opt plugin.Options) ([]msg.Service, error) {
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ip := dnsutil.ExtractAddressFromReverse(state.Name())
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if ip == "" {
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_, e := k.Records(ctx, state, exact)
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return nil, e
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}
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records := k.serviceRecordForIP(ip, state.Name())
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if len(records) == 0 {
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return records, errNoItems
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}
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return records, nil
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}
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// serviceRecordForIP gets a service record with a cluster ip matching the ip argument
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// If a service cluster ip does not match, it checks all endpoints
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func (k *Kubernetes) serviceRecordForIP(ip, name string) []msg.Service {
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// First check services with cluster ips
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for _, service := range k.APIConn.SvcIndexReverse(ip) {
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if len(k.Namespaces) > 0 && !k.namespaceExposed(service.Namespace) {
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continue
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}
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domain := strings.Join([]string{service.Name, service.Namespace, Svc, k.primaryZone()}, ".")
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return []msg.Service{{Host: domain, TTL: k.ttl}}
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}
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// If no cluster ips match, search endpoints
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var svcs []msg.Service
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for _, ep := range k.APIConn.EpIndexReverse(ip) {
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if len(k.Namespaces) > 0 && !k.namespaceExposed(ep.Namespace) {
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continue
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}
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for _, eps := range ep.Subsets {
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for _, addr := range eps.Addresses {
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// The endpoint's Hostname will be set if this endpoint is supposed to generate a PTR.
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// So only return reverse records that match the IP AND have a non-empty hostname.
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// Kubernetes more or less keeps this to one canonical service/endpoint per IP, but in the odd event there
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// are multiple endpoints for the same IP with hostname set, return them all rather than selecting one
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// arbitrarily.
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if addr.IP == ip && addr.Hostname != "" {
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domain := strings.Join([]string{addr.Hostname, ep.Index, Svc, k.primaryZone()}, ".")
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svcs = append(svcs, msg.Service{Host: domain, TTL: k.ttl})
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}
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}
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}
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}
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return svcs
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}
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