Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Added DNS Reverse Record logic for service IPs #26226

Merged
merged 1 commit into from
Jun 3, 2016
Merged

Added DNS Reverse Record logic for service IPs #26226

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Jump to
Jump to file
Failed to load files.
Diff view
Diff view
54 changes: 43 additions & 11 deletions pkg/dns/dns.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,9 @@ const (
// A subdomain added to the user specified dmoain for all pods.
podSubdomain = "pod"

// arpaSuffix is the standard suffix for PTR IP reverse lookups.
arpaSuffix = ".in-addr.arpa."

// Resync period for the kube controller loop.
resyncPeriod = 5 * time.Minute

Expand Down Expand Up @@ -78,6 +81,8 @@ type KubeDNS struct {
// A Records and SRV Records for (regular) services and headless Services.
cache *TreeCache

reverseRecordMap map[string]*skymsg.Service

// caller is responsible for using the cacheLock before invoking methods on cache
// the cache is not thread-safe, and the caller can guarantee thread safety by using
// the cacheLock
Expand Down Expand Up @@ -105,12 +110,13 @@ type KubeDNS struct {

func NewKubeDNS(client clientset.Interface, domain string, federations map[string]string) *KubeDNS {
kd := &KubeDNS{
kubeClient: client,
domain: domain,
cache: NewTreeCache(),
cacheLock: sync.RWMutex{},
domainPath: reverseArray(strings.Split(strings.TrimRight(domain, "."), ".")),
federations: federations,
kubeClient: client,
domain: domain,
cache: NewTreeCache(),
cacheLock: sync.RWMutex{},
reverseRecordMap: make(map[string]*skymsg.Service),
domainPath: reverseArray(strings.Split(strings.TrimRight(domain, "."), ".")),
federations: federations,
}
kd.setEndpointsStore()
kd.setServicesStore()
Expand Down Expand Up @@ -225,6 +231,7 @@ func (kd *KubeDNS) removeService(obj interface{}) {
kd.cacheLock.Lock()
defer kd.cacheLock.Unlock()
kd.cache.deletePath(subCachePath...)
delete(kd.reverseRecordMap, s.Spec.ClusterIP)
}
}

Expand Down Expand Up @@ -283,9 +290,13 @@ func (kd *KubeDNS) newPortalService(service *kapi.Service) {
}
}
subCachePath := append(kd.domainPath, serviceSubdomain, service.Namespace)
host := kd.getServiceFQDN(service)
reverseRecord, _ := getSkyMsg(host, 0)

kd.cacheLock.Lock()
defer kd.cacheLock.Unlock()
kd.cache.setSubCache(service.Name, subCache, subCachePath...)
kd.reverseRecordMap[service.Spec.ClusterIP] = reverseRecord
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

should we add reverse records for petset pods (with hostname and subdomain set AND a governing headless service? Maybe that's yet another followup. Can you just file an issue on that?

Copy link

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Filed issue #26752 to track this.

}

func (kd *KubeDNS) generateRecordsForHeadlessService(e *kapi.Endpoints, svc *kapi.Service) error {
Expand Down Expand Up @@ -430,17 +441,34 @@ func (kd *KubeDNS) Records(name string, exact bool) ([]skymsg.Service, error) {
func (kd *KubeDNS) ReverseRecord(name string) (*skymsg.Service, error) {
glog.Infof("Received ReverseRecord Request:%s", name)

segments := strings.Split(strings.TrimRight(name, "."), ".")
// if portalIP is not a valid IP, the reverseRecordMap lookup will fail
portalIP, ok := extractIP(name)
if !ok {
return nil, fmt.Errorf("does not support reverse lookup for %s", name)
}

for _, k := range segments {
if k == "*" {
return nil, fmt.Errorf("reverse can not contain wildcards")
}
kd.cacheLock.RLock()
defer kd.cacheLock.RUnlock()
if reverseRecord, ok := kd.reverseRecordMap[portalIP]; ok {
return reverseRecord, nil
}

return nil, fmt.Errorf("must be exactly one service record")
}

// extractIP turns a standard PTR reverse record lookup name
// into an IP address
func extractIP(reverseName string) (string, bool) {
if !strings.HasSuffix(reverseName, arpaSuffix) {
return "", false
}
search := strings.TrimSuffix(reverseName, arpaSuffix)

// reverse the segments and then combine them
segments := reverseArray(strings.Split(search, "."))
return strings.Join(segments, "."), true
}

// e.g {"local", "cluster", "pod", "default", "10-0-0-1"}
func (kd *KubeDNS) isPodRecord(path []string) bool {
if len(path) != len(kd.domainPath)+3 {
Expand Down Expand Up @@ -602,6 +630,10 @@ func (kd *KubeDNS) getClusterZone() (string, error) {
return zone, nil
}

func (kd *KubeDNS) getServiceFQDN(service *kapi.Service) string {
return strings.Join([]string{service.Name, service.Namespace, serviceSubdomain, kd.domain}, ".")
}

func reverseArray(arr []string) []string {
for i := 0; i < len(arr)/2; i++ {
j := len(arr) - i - 1
Expand Down
33 changes: 26 additions & 7 deletions pkg/dns/dns_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -41,13 +41,14 @@ const (

func newKubeDNS() *KubeDNS {
kd := &KubeDNS{
domain: testDomain,
endpointsStore: cache.NewStore(cache.MetaNamespaceKeyFunc),
servicesStore: cache.NewStore(cache.MetaNamespaceKeyFunc),
cache: NewTreeCache(),
cacheLock: sync.RWMutex{},
domainPath: reverseArray(strings.Split(strings.TrimRight(testDomain, "."), ".")),
nodesStore: cache.NewStore(cache.MetaNamespaceKeyFunc),
domain: testDomain,
endpointsStore: cache.NewStore(cache.MetaNamespaceKeyFunc),
servicesStore: cache.NewStore(cache.MetaNamespaceKeyFunc),
cache: NewTreeCache(),
reverseRecordMap: make(map[string]*skymsg.Service),
cacheLock: sync.RWMutex{},
domainPath: reverseArray(strings.Split(strings.TrimRight(testDomain, "."), ".")),
nodesStore: cache.NewStore(cache.MetaNamespaceKeyFunc),
}
return kd
}
Expand All @@ -71,9 +72,11 @@ func TestUnnamedSinglePortService(t *testing.T) {
// Add the service
kd.newService(s)
assertDNSForClusterIP(t, kd, s)
assertReverseRecord(t, kd, s)
// Delete the service
kd.removeService(s)
assertNoDNSForClusterIP(t, kd, s)
assertNoReverseRecord(t, kd, s)
}

func TestNamedSinglePortService(t *testing.T) {
Expand Down Expand Up @@ -457,6 +460,22 @@ func assertDNSForClusterIP(t *testing.T, kd *KubeDNS, s *kapi.Service) {
}
}

func assertReverseRecord(t *testing.T, kd *KubeDNS, s *kapi.Service) {
segments := reverseArray(strings.Split(s.Spec.ClusterIP, "."))
reverseLookup := fmt.Sprintf("%s%s", strings.Join(segments, "."), arpaSuffix)
reverseRecord, err := kd.ReverseRecord(reverseLookup)
require.NoError(t, err)
assert.Equal(t, kd.getServiceFQDN(s), reverseRecord.Host)
}

func assertNoReverseRecord(t *testing.T, kd *KubeDNS, s *kapi.Service) {
segments := reverseArray(strings.Split(s.Spec.ClusterIP, "."))
reverseLookup := fmt.Sprintf("%s%s", strings.Join(segments, "."), arpaSuffix)
reverseRecord, err := kd.ReverseRecord(reverseLookup)
require.Error(t, err)
require.Nil(t, reverseRecord)
}

func getEquivalentQueries(serviceFQDN, namespace string) []string {
return []string{
serviceFQDN,
Expand Down
34 changes: 26 additions & 8 deletions test/e2e/dns.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -117,7 +117,7 @@ func createDNSPod(namespace, wheezyProbeCmd, jessieProbeCmd string, useAnnotatio
return dnsPod
}

func createProbeCommand(namesToResolve []string, hostEntries []string, fileNamePrefix, namespace string) (string, []string) {
func createProbeCommand(namesToResolve []string, hostEntries []string, ptrLookupIP string, fileNamePrefix, namespace string) (string, []string) {
fileNames := make([]string, 0, len(namesToResolve)*2)
probeCmd := "for i in `seq 1 600`; do "
for _, name := range namesToResolve {
Expand Down Expand Up @@ -150,6 +150,16 @@ func createProbeCommand(namesToResolve []string, hostEntries []string, fileNameP
fileNames = append(fileNames, podARecByUDPFileName)
fileNames = append(fileNames, podARecByTCPFileName)

if len(ptrLookupIP) > 0 {
ptrLookup := fmt.Sprintf("%s.in-addr.arpa.", strings.Join(reverseArray(strings.Split(ptrLookupIP, ".")), "."))
ptrRecByUDPFileName := fmt.Sprintf("%s_udp@PTR", ptrLookupIP)
ptrRecByTCPFileName := fmt.Sprintf("%s_tcp@PTR", ptrLookupIP)
probeCmd += fmt.Sprintf(`test -n "$$(dig +notcp +noall +answer +search %s PTR)" && echo OK > /results/%s;`, ptrLookup, ptrRecByUDPFileName)
probeCmd += fmt.Sprintf(`test -n "$$(dig +tcp +noall +answer +search %s PTR)" && echo OK > /results/%s;`, ptrLookup, ptrRecByTCPFileName)
fileNames = append(fileNames, ptrRecByUDPFileName)
fileNames = append(fileNames, ptrRecByTCPFileName)
}

probeCmd += "sleep 1; done"
return probeCmd, fileNames
}
Expand Down Expand Up @@ -256,6 +266,14 @@ func createServiceSpec(serviceName string, isHeadless bool, selector map[string]
return headlessService
}

func reverseArray(arr []string) []string {
for i := 0; i < len(arr)/2; i++ {
j := len(arr) - i - 1
arr[i], arr[j] = arr[j], arr[i]
}
return arr
}

var _ = framework.KubeDescribe("DNS", func() {
f := framework.NewDefaultFramework("dns")

Expand All @@ -274,8 +292,8 @@ var _ = framework.KubeDescribe("DNS", func() {
}
hostFQDN := fmt.Sprintf("%s.%s.%s.svc.cluster.local", dnsTestPodHostName, dnsTestServiceName, f.Namespace.Name)
hostEntries := []string{hostFQDN, dnsTestPodHostName}
wheezyProbeCmd, wheezyFileNames := createProbeCommand(namesToResolve, hostEntries, "wheezy", f.Namespace.Name)
jessieProbeCmd, jessieFileNames := createProbeCommand(namesToResolve, hostEntries, "jessie", f.Namespace.Name)
wheezyProbeCmd, wheezyFileNames := createProbeCommand(namesToResolve, hostEntries, "", "wheezy", f.Namespace.Name)
jessieProbeCmd, jessieFileNames := createProbeCommand(namesToResolve, hostEntries, "", "jessie", f.Namespace.Name)
By("Running these commands on wheezy:" + wheezyProbeCmd + "\n")
By("Running these commands on jessie:" + jessieProbeCmd + "\n")

Expand All @@ -301,7 +319,7 @@ var _ = framework.KubeDescribe("DNS", func() {
}()

regularService := createServiceSpec("test-service-2", false, testServiceSelector)
_, err = f.Client.Services(f.Namespace.Name).Create(regularService)
regularService, err = f.Client.Services(f.Namespace.Name).Create(regularService)
Expect(err).NotTo(HaveOccurred())
defer func() {
By("deleting the test service")
Expand All @@ -320,8 +338,8 @@ var _ = framework.KubeDescribe("DNS", func() {
fmt.Sprintf("_http._tcp.%s.%s.svc", regularService.Name, f.Namespace.Name),
}

wheezyProbeCmd, wheezyFileNames := createProbeCommand(namesToResolve, nil, "wheezy", f.Namespace.Name)
jessieProbeCmd, jessieFileNames := createProbeCommand(namesToResolve, nil, "jessie", f.Namespace.Name)
wheezyProbeCmd, wheezyFileNames := createProbeCommand(namesToResolve, nil, regularService.Spec.ClusterIP, "wheezy", f.Namespace.Name)
jessieProbeCmd, jessieFileNames := createProbeCommand(namesToResolve, nil, regularService.Spec.ClusterIP, "jessie", f.Namespace.Name)
By("Running these commands on wheezy:" + wheezyProbeCmd + "\n")
By("Running these commands on jessie:" + jessieProbeCmd + "\n")

Expand Down Expand Up @@ -353,8 +371,8 @@ var _ = framework.KubeDescribe("DNS", func() {
hostFQDN := fmt.Sprintf("%s.%s.%s.svc.cluster.local", podHostname, serviceName, f.Namespace.Name)
hostNames := []string{hostFQDN, podHostname}
namesToResolve := []string{hostFQDN}
wheezyProbeCmd, wheezyFileNames := createProbeCommand(namesToResolve, hostNames, "wheezy", f.Namespace.Name)
jessieProbeCmd, jessieFileNames := createProbeCommand(namesToResolve, hostNames, "jessie", f.Namespace.Name)
wheezyProbeCmd, wheezyFileNames := createProbeCommand(namesToResolve, hostNames, "", "wheezy", f.Namespace.Name)
jessieProbeCmd, jessieFileNames := createProbeCommand(namesToResolve, hostNames, "", "jessie", f.Namespace.Name)
By("Running these commands on wheezy:" + wheezyProbeCmd + "\n")
By("Running these commands on jessie:" + jessieProbeCmd + "\n")

Expand Down