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// Package kubernetes provides the kubernetes backend.
package kubernetes
import (
"errors"
"log"
"strings"
"time"
"github.com/miekg/coredns/middleware"
"github.com/miekg/coredns/middleware/kubernetes/msg"
"github.com/miekg/coredns/middleware/kubernetes/nametemplate"
"github.com/miekg/coredns/middleware/kubernetes/util"
"github.com/miekg/coredns/middleware/proxy"
"github.com/miekg/dns"
"k8s.io/kubernetes/pkg/api"
unversionedapi "k8s.io/kubernetes/pkg/api/unversioned"
unversionedclient "k8s.io/kubernetes/pkg/client/unversioned"
"k8s.io/kubernetes/pkg/client/unversioned/clientcmd"
clientcmdapi "k8s.io/kubernetes/pkg/client/unversioned/clientcmd/api"
"k8s.io/kubernetes/pkg/labels"
)
type Kubernetes struct {
Next middleware.Handler
Zones []string
Proxy proxy.Proxy // Proxy for looking up names during the resolution process
APIEndpoint string
APIConn *dnsController
ResyncPeriod time.Duration
NameTemplate *nametemplate.NameTemplate
Namespaces []string
LabelSelector *unversionedapi.LabelSelector
Selector *labels.Selector
}
func (g *Kubernetes) InitKubeCache() error {
// For a custom api server or running outside a k8s cluster
// set URL in env.KUBERNETES_MASTER or set endpoint in Corefile
loadingRules := clientcmd.NewDefaultClientConfigLoadingRules()
overrides := &clientcmd.ConfigOverrides{}
if len(g.APIEndpoint) > 0 {
overrides.ClusterInfo = clientcmdapi.Cluster{Server: g.APIEndpoint}
}
clientConfig := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(loadingRules, overrides)
config, err := clientConfig.ClientConfig()
if err != nil {
return err
}
kubeClient, err := unversionedclient.New(config)
if err != nil {
log.Printf("[ERROR] Failed to create kubernetes notification controller: %v", err)
return err
}
if g.LabelSelector == nil {
log.Printf("[INFO] Kubernetes middleware configured without a label selector. No label-based filtering will be performed.")
} else {
var selector labels.Selector
selector, err = unversionedapi.LabelSelectorAsSelector(g.LabelSelector)
g.Selector = &selector
if err != nil {
log.Printf("[ERROR] Unable to create Selector for LabelSelector '%s'.Error was: %s", g.LabelSelector, err)
return err
}
log.Printf("[INFO] Kubernetes middleware configured with the label selector '%s'. Only kubernetes objects matching this label selector will be exposed.", unversionedapi.FormatLabelSelector(g.LabelSelector))
}
g.APIConn = newdnsController(kubeClient, g.ResyncPeriod, g.Selector)
return err
}
// getZoneForName returns the zone string that matches the name and a
// list of the DNS labels from name that are within the zone.
// For example, if "coredns.local" is a zone configured for the
// Kubernetes middleware, then getZoneForName("a.b.coredns.local")
// will return ("coredns.local", ["a", "b"]).
func (g *Kubernetes) getZoneForName(name string) (string, []string) {
var zone string
var serviceSegments []string
for _, z := range g.Zones {
if dns.IsSubDomain(z, name) {
zone = z
serviceSegments = dns.SplitDomainName(name)
serviceSegments = serviceSegments[:len(serviceSegments)-dns.CountLabel(zone)]
break
}
}
return zone, serviceSegments
}
// Records looks up services in kubernetes.
// If exact is true, it will lookup just
// this name. This is used when find matches when completing SRV lookups
// for instance.
func (g *Kubernetes) Records(name string, exact bool) ([]msg.Service, error) {
// TODO: refector this.
// Right now GetNamespaceFromSegmentArray do not supports PRE queries
if strings.HasSuffix(name, arpaSuffix) {
ip, _ := extractIP(name)
records := g.getServiceRecordForIP(ip, name)
return records, nil
}
var (
serviceName string
namespace string
typeName string
)
zone, serviceSegments := g.getZoneForName(name)
// TODO: Implementation above globbed together segments for the serviceName if
// multiple segments remained. Determine how to do similar globbing using
// the template-based implementation.
namespace = g.NameTemplate.GetNamespaceFromSegmentArray(serviceSegments)
serviceName = g.NameTemplate.GetServiceFromSegmentArray(serviceSegments)
typeName = g.NameTemplate.GetTypeFromSegmentArray(serviceSegments)
if namespace == "" {
err := errors.New("Parsing query string did not produce a namespace value. Assuming wildcard namespace.")
log.Printf("[WARN] %v\n", err)
namespace = util.WildcardStar
}
if serviceName == "" {
err := errors.New("Parsing query string did not produce a serviceName value. Assuming wildcard serviceName.")
log.Printf("[WARN] %v\n", err)
serviceName = util.WildcardStar
}
nsWildcard := util.SymbolContainsWildcard(namespace)
serviceWildcard := util.SymbolContainsWildcard(serviceName)
// Abort if the namespace does not contain a wildcard, and namespace is not published per CoreFile
// Case where namespace contains a wildcard is handled in Get(...) method.
if (!nsWildcard) && (len(g.Namespaces) > 0) && (!util.StringInSlice(namespace, g.Namespaces)) {
return nil, nil
}
log.Printf("[debug] before g.Get(namespace, nsWildcard, serviceName, serviceWildcard): %v %v %v %v", namespace, nsWildcard, serviceName, serviceWildcard)
k8sItems, err := g.Get(namespace, nsWildcard, serviceName, serviceWildcard)
if err != nil {
return nil, err
}
if k8sItems == nil {
// Did not find item in k8s
return nil, nil
}
records := g.getRecordsForServiceItems(k8sItems, nametemplate.NameValues{TypeName: typeName, ServiceName: serviceName, Namespace: namespace, Zone: zone})
return records, nil
}
// TODO: assemble name from parts found in k8s data based on name template rather than reusing query string
func (g *Kubernetes) getRecordsForServiceItems(serviceItems []api.Service, values nametemplate.NameValues) []msg.Service {
var records []msg.Service
for _, item := range serviceItems {
clusterIP := item.Spec.ClusterIP
// Create records by constructing record name from template...
//values.Namespace = item.Metadata.Namespace
//values.ServiceName = item.Metadata.Name
//s := msg.Service{Host: g.NameTemplate.GetRecordNameFromNameValues(values)}
//records = append(records, s)
// Create records for each exposed port...
for _, p := range item.Spec.Ports {
s := msg.Service{Host: clusterIP, Port: int(p.Port)}
records = append(records, s)
}
}
return records
}
// Get performs the call to the Kubernetes http API.
func (g *Kubernetes) Get(namespace string, nsWildcard bool, servicename string, serviceWildcard bool) ([]api.Service, error) {
serviceList := g.APIConn.GetServiceList()
var resultItems []api.Service
for _, item := range serviceList.Items {
if symbolMatches(namespace, item.Namespace, nsWildcard) && symbolMatches(servicename, item.Name, serviceWildcard) {
// If namespace has a wildcard, filter results against Corefile namespace list.
// (Namespaces without a wildcard were filtered before the call to this function.)
if nsWildcard && (len(g.Namespaces) > 0) && (!util.StringInSlice(item.Namespace, g.Namespaces)) {
continue
}
resultItems = append(resultItems, item)
}
}
return resultItems, nil
}
func symbolMatches(queryString string, candidateString string, wildcard bool) bool {
result := false
switch {
case !wildcard:
result = (queryString == candidateString)
case queryString == util.WildcardStar:
result = true
case queryString == util.WildcardAny:
result = true
}
return result
}
// kubernetesNameError checks if the error is ErrorCodeKeyNotFound from kubernetes.
func isKubernetesNameError(err error) bool {
return false
}
func (g *Kubernetes) getServiceRecordForIP(ip, name string) []msg.Service {
svcList, err := g.APIConn.svcLister.List()
if err != nil {
return nil
}
for _, service := range svcList.Items {
if service.Spec.ClusterIP == ip {
return []msg.Service{msg.Service{Host: ip}}
}
}
return nil
}
const (
priority = 10 // default priority when nothing is set
ttl = 300 // default ttl when nothing is set
minTtl = 60
hostmaster = "hostmaster"
k8sTimeout = 5 * time.Second
)
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