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Add k8s external service CNAMEs (#677)

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* Add external service cnames

* remove cruft

* update CI k8s version

* change CI k8s version

* min k8s ver for ext services

* trying k8s 1.5

* k8s 1.5 requires ports spec

* remove kruft

* update dns schema version
This commit is contained in:
Chris O'Haver 2017-05-30 08:20:39 -04:00 • committed by Miek Gieben
parent 2f2c90f391
commit d917ff5ac2
11 changed files with 293 additions and 16 deletions
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2
.travis.yml
View file

@ -12,7 +12,7 @@ go:
go_import_path: github.com/coredns/coredns
env:
- ETCD_VERSION=2.3.1 K8S_VERSION=1.3.7 KUBECTL="docker exec hyperkube /hyperkube kubectl" DNS_ARGUMENTS=""
- ETCD_VERSION=2.3.1 K8S_VERSION=1.5.0 KUBECTL="docker exec hyperkube /hyperkube kubectl" DNS_ARGUMENTS=""
# In the Travis VM-based build environment, IPv6 networking is not
# enabled by default. The sysctl operations below enable IPv6.

14
.travis/kubernetes/dns-test.yaml
View file

@ -183,3 +183,17 @@ spec:
- name: c-port
port: 1234
protocol: UDP
---
apiVersion: v1
kind: Service
metadata:
name: ext-svc
namespace: test-1
spec:
type: ExternalName
externalName: example.net
ports:
- name: c-port
port: 1234
protocol: UDP

10
middleware/backend_lookup.go
View file

@ -25,7 +25,7 @@ func A(b ServiceBackend, zone string, state request.Request, previousRecords []d
what, ip := serv.HostType()
switch what {
case dns.TypeANY:
case dns.TypeCNAME:
if Name(state.Name()).Matches(dns.Fqdn(serv.Host)) {
// x CNAME x is a direct loop, don't add those
continue
@ -92,7 +92,7 @@ func AAAA(b ServiceBackend, zone string, state request.Request, previousRecords
what, ip := serv.HostType()
switch what {
case dns.TypeANY:
case dns.TypeCNAME:
// Try to resolve as CNAME if it's not an IP, but only if we don't create loops.
if Name(state.Name()).Matches(dns.Fqdn(serv.Host)) {
// x CNAME x is a direct loop, don't add those
@ -182,7 +182,7 @@ func SRV(b ServiceBackend, zone string, state request.Request, opt Options) (rec
what, ip := serv.HostType()
switch what {
case dns.TypeANY:
case dns.TypeCNAME:
srv := serv.NewSRV(state.QName(), weight)
records = append(records, srv)
@ -250,7 +250,7 @@ func MX(b ServiceBackend, zone string, state request.Request, opt Options) (reco
}
what, ip := serv.HostType()
switch what {
case dns.TypeANY:
case dns.TypeCNAME:
mx := serv.NewMX(state.QName())
records = append(records, mx)
if _, ok := lookup[mx.Mx]; ok {
@ -364,7 +364,7 @@ func NS(b ServiceBackend, zone string, state request.Request, opt Options) (reco
for _, serv := range services {
what, ip := serv.HostType()
switch what {
case dns.TypeANY:
case dns.TypeCNAME:
return nil, nil, debug, fmt.Errorf("NS record must be an IP address: %s", serv.Host)
case dns.TypeA, dns.TypeAAAA:

4
middleware/etcd/msg/type.go
View file

@ -11,7 +11,7 @@ import (
//
// dns.TypeA: the service's Host field contains an A record.
// dns.TypeAAAA: the service's Host field contains an AAAA record.
// dns.TypeANY: the service's Host field contains a name.
// dns.TypeCNAME: the service's Host field contains a name.
//
// Note that a service can double/triple as a TXT record or MX record.
func (s *Service) HostType() (what uint16, normalized net.IP) {
@ -20,7 +20,7 @@ func (s *Service) HostType() (what uint16, normalized net.IP) {
switch {
case ip == nil:
return dns.TypeANY, nil
return dns.TypeCNAME, nil
case ip.To4() != nil:
return dns.TypeA, ip.To4()

6
middleware/etcd/msg/type_test.go
View file

@ -11,11 +11,11 @@ func TestType(t *testing.T) {
serv Service
expectedType uint16
}{
{Service{Host: "example.org"}, dns.TypeANY},
{Service{Host: "example.org"}, dns.TypeCNAME},
{Service{Host: "127.0.0.1"}, dns.TypeA},
{Service{Host: "2000::3"}, dns.TypeAAAA},
{Service{Host: "2000..3"}, dns.TypeANY},
{Service{Host: "127.0.0.257"}, dns.TypeANY},
{Service{Host: "2000..3"}, dns.TypeCNAME},
{Service{Host: "127.0.0.257"}, dns.TypeCNAME},
{Service{Host: "127.0.0.252", Mail: true}, dns.TypeA},
{Service{Host: "127.0.0.252", Mail: true, Text: "a"}, dns.TypeA},
{Service{Host: "127.0.0.254", Mail: false, Text: "a"}, dns.TypeA},

7
middleware/kubernetes/README.md
View file

@ -108,6 +108,13 @@ kubernetes coredns.local {
#
cidrs 10.0.0.0/24 10.0.10.0/25
# upstream <address> [<address>] ...
#
# Defines upstream resolvers used for resolving services that point to
# external hosts (External Services). <address> can be an ip, and ip:port, or
# a path to a file structured like resolv.conf.
upstream 12.34.56.78:53
# fallthrough
#
# If a query for a record in the cluster zone results in NXDOMAIN,

35
middleware/kubernetes/kubernetes.go
View file

@ -55,7 +55,7 @@ const (
// PodModeInsecure is where pod requests are answered without verfying they exist
PodModeInsecure = "insecure"
// DNSSchemaVersion is the schema version: https://github.com/kubernetes/dns/blob/master/docs/specification.md
DNSSchemaVersion = "1.0.0"
DNSSchemaVersion = "1.0.1"
)
type endpoint struct {
@ -97,7 +97,7 @@ func (k *Kubernetes) Services(state request.Request, exact bool, opt middleware.
}
switch state.Type() {
case "A", "SRV":
case "A", "CNAME":
if state.Type() == "A" && isDefaultNS(state.Name(), r) {
// If this is an A request for "ns.dns", respond with a "fake" record for coredns.
// SOA records always use this hardcoded name
@ -106,6 +106,16 @@ func (k *Kubernetes) Services(state request.Request, exact bool, opt middleware.
}
s, e := k.Records(r)
return s, nil, e // Haven't implemented debug queries yet.
case "SRV":
s, e := k.Records(r)
// SRV for external services is not yet implemented, so remove those records
noext := []msg.Service{}
for _, svc := range s {
if t, _ := svc.HostType(); t != dns.TypeCNAME {
noext = append(noext, svc)
}
}
return noext, nil, e
case "TXT":
err := k.recordsForTXT(r, &svcs)
return svcs, nil, err
@ -373,6 +383,14 @@ func (k *Kubernetes) getRecordsForK8sItems(services []service, pods []pod, zone
Port: int(p.Port)}
records = append(records, s)
}
// If the addr is not an IP (i.e. an external service), add the record ...
s := msg.Service{
Key: strings.Join([]string{zonePath, "svc", svc.namespace, svc.name}, "/"),
Host: svc.addr}
if t, _ := s.HostType(); t == dns.TypeCNAME {
records = append(records, s)
}
}
}
@ -466,8 +484,16 @@ func (k *Kubernetes) findServices(r recordRequest) ([]service, error) {
if nsWildcard && (len(k.Namespaces) > 0) && (!dnsstrings.StringInSlice(svc.Namespace, k.Namespaces)) {
continue
}
s := service{name: svc.Name, namespace: svc.Namespace, addr: svc.Spec.ClusterIP}
if s.addr != api.ClusterIPNone {
s := service{name: svc.Name, namespace: svc.Namespace}
// External Service
if svc.Spec.ExternalName != "" {
s.addr = svc.Spec.ExternalName
resultItems = append(resultItems, s)
continue
}
// ClusterIP service
if svc.Spec.ClusterIP != api.ClusterIPNone {
s.addr = svc.Spec.ClusterIP
for _, p := range svc.Spec.Ports {
if !(symbolMatches(r.port, strings.ToLower(p.Name), portWildcard) && symbolMatches(r.protocol, strings.ToLower(string(p.Protocol)), protocolWildcard)) {
continue
@ -478,6 +504,7 @@ func (k *Kubernetes) findServices(r recordRequest) ([]service, error) {
continue
}
// Headless service
s.addr = svc.Spec.ClusterIP
endpointsList := k.APIConn.EndpointsList()
for _, ep := range endpointsList.Items {

82
middleware/kubernetes/kubernetes_test.go
View file

@ -9,7 +9,9 @@ import (
"github.com/miekg/dns"
"k8s.io/client-go/1.5/pkg/api"
"github.com/coredns/coredns/middleware"
"github.com/coredns/coredns/middleware/etcd/msg"
"github.com/coredns/coredns/request"
)
func TestRecordForTXT(t *testing.T) {
@ -277,3 +279,83 @@ func TestIpFromPodName(t *testing.T) {
}
}
}
type APIConnServiceTest struct{}
func (APIConnServiceTest) Run() {
return
}
func (APIConnServiceTest) Stop() error {
return nil
}
func (APIConnServiceTest) ServiceList() []*api.Service {
svcs := []*api.Service{
{
ObjectMeta: api.ObjectMeta{
Name: "external",
Namespace: "testns",
},
Spec: api.ServiceSpec{
ExternalName: "coredns.io",
Ports: []api.ServicePort{{
Name: "http",
Protocol: "tcp",
Port: 80,
}},
},
},
}
return svcs
}
func (APIConnServiceTest) PodIndex(string) []interface{} {
return nil
}
func (APIConnServiceTest) EndpointsList() api.EndpointsList {
return api.EndpointsList{}
}
func TestServices(t *testing.T) {
k := Kubernetes{Zones: []string{"interwebs.test"}}
k.APIConn = &APIConnServiceTest{}
type svcAns struct {
host string
key string
}
type svcTest struct {
qname string
qtype uint16
answer svcAns
}
tests := []svcTest{
// External Services
{qname: "external.testns.svc.interwebs.test.", qtype: dns.TypeCNAME, answer: svcAns{host: "coredns.io", key: "/coredns/test/interwebs/svc/testns/external"}},
}
for _, test := range tests {
state := request.Request{
Req: &dns.Msg{Question: []dns.Question{{Name: test.qname, Qtype: test.qtype}}},
}
svcs, _, e := k.Services(state, false, middleware.Options{})
if e != nil {
t.Errorf("Query '%v' got error '%v'", test.qname, e)
}
if len(svcs) != 1 {
t.Errorf("Query %v %v: expected expected 1 answer, got %v", test.qname, dns.TypeToString[test.qtype], len(svcs))
} else {
if test.answer.host != svcs[0].Host {
t.Errorf("Query %v %v: expected host '%v', got '%v'", test.qname, dns.TypeToString[test.qtype], test.answer.host, svcs[0].Host)
}
if test.answer.key != svcs[0].Key {
t.Errorf("Query %v %v: expected key '%v', got '%v'", test.qname, dns.TypeToString[test.qtype], test.answer.key, svcs[0].Key)
}
}
}
}

12
middleware/kubernetes/setup.go
View file

@ -9,6 +9,8 @@ import (
"github.com/coredns/coredns/core/dnsserver"
"github.com/coredns/coredns/middleware"
"github.com/coredns/coredns/middleware/pkg/dnsutil"
"github.com/coredns/coredns/middleware/proxy"
"github.com/mholt/caddy"
unversionedapi "k8s.io/client-go/1.5/pkg/api/unversioned"
@ -165,6 +167,16 @@ func kubernetesParse(c *caddy.Controller) (*Kubernetes, error) {
continue
}
return nil, c.ArgErr()
case "upstream":
args := c.RemainingArgs()
if len(args) == 0 {
return nil, c.ArgErr()
}
ups, err := dnsutil.ParseHostPortOrFile(args...)
if err != nil {
return nil, err
}
k8s.Proxy = proxy.NewLookup(ups)
}
}
return k8s, nil

84
middleware/kubernetes/setup_test.go
View file

@ -28,6 +28,7 @@ func TestKubernetesParse(t *testing.T) {
expectedPodMode string
expectedCidrs []net.IPNet
expectedFallthrough bool
expectedUpstreams []string
}{
// positive
{
@ -42,6 +43,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"kubernetes keyword with multiple zones",
@ -55,6 +57,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"kubernetes keyword with zone and empty braces",
@ -69,6 +72,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"endpoint keyword with url",
@ -84,6 +88,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"namespaces keyword with one namespace",
@ -99,6 +104,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"namespaces keyword with multiple namespaces",
@ -114,6 +120,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"resync period in seconds",
@ -129,6 +136,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"resync period in minutes",
@ -144,6 +152,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"basic label selector",
@ -159,6 +168,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"multi-label selector",
@ -174,6 +184,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"fully specified valid config",
@ -193,6 +204,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
true,
nil,
},
// negative
{
@ -207,6 +219,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"kubernetes keyword without a zone",
@ -220,6 +233,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"endpoint keyword without an endpoint value",
@ -235,6 +249,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"namespace keyword without a namespace value",
@ -250,6 +265,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"resyncperiod keyword without a duration value",
@ -265,6 +281,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"resync period no units",
@ -280,6 +297,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"resync period invalid",
@ -295,6 +313,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"labels with no selector value",
@ -310,6 +329,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
{
"labels with invalid selector value",
@ -325,6 +345,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
// pods disabled
{
@ -341,6 +362,7 @@ func TestKubernetesParse(t *testing.T) {
PodModeDisabled,
nil,
false,
nil,
},
// pods insecure
{
@ -357,6 +379,7 @@ func TestKubernetesParse(t *testing.T) {
PodModeInsecure,
nil,
false,
nil,
},
// pods verified
{
@ -373,6 +396,7 @@ func TestKubernetesParse(t *testing.T) {
PodModeVerified,
nil,
false,
nil,
},
// pods invalid
{
@ -389,6 +413,7 @@ func TestKubernetesParse(t *testing.T) {
PodModeVerified,
nil,
false,
nil,
},
// cidrs ok
{
@ -405,6 +430,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
[]net.IPNet{parseCidr("10.0.0.0/24"), parseCidr("10.0.1.0/24")},
false,
nil,
},
// cidrs ok
{
@ -421,6 +447,7 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
// fallthrough invalid
{
@ -437,6 +464,41 @@ func TestKubernetesParse(t *testing.T) {
defaultPodMode,
nil,
false,
nil,
},
// Valid upstream
{
"valid upstream",
`kubernetes coredns.local {
upstream 13.14.15.16:53
}`,
false,
"",
1,
0,
defaultResyncPeriod,
"",
defaultPodMode,
nil,
false,
[]string{"13.14.15.16:53"},
},
// Invalid upstream
{
"valid upstream",
`kubernetes coredns.local {
upstream 13.14.15.16orange
}`,
true,
"not an IP address or file: \"13.14.15.16orange\"",
-1,
0,
defaultResyncPeriod,
"",
defaultPodMode,
nil,
false,
nil,
},
}
@ -515,6 +577,28 @@ func TestKubernetesParse(t *testing.T) {
if foundFallthrough != test.expectedFallthrough {
t.Errorf("Test %d: Expected kubernetes controller to be initialized with fallthrough '%v'. Instead found fallthrough '%v' for input '%s'", i, test.expectedFallthrough, foundFallthrough, test.input)
}
// upstream
foundUpstreams := k8sController.Proxy.Upstreams
if test.expectedUpstreams == nil {
if foundUpstreams != nil {
t.Errorf("Test %d: Expected kubernetes controller to not be initialized with upstreams for input '%s'", i, test.input)
}
} else {
if foundUpstreams == nil {
t.Errorf("Test %d: Expected kubernetes controller to be initialized with upstreams for input '%s'", i, test.input)
} else {
if len(*foundUpstreams) != len(test.expectedUpstreams) {
t.Errorf("Test %d: Expected kubernetes controller to be initialized with %d upstreams. Instead found %d upstreams for input '%s'", i, len(test.expectedUpstreams), len(*foundUpstreams), test.input)
}
for j, want := range test.expectedUpstreams {
got := (*foundUpstreams)[j].Select().Name
if got != want {
t.Errorf("Test %d: Expected kubernetes controller to be initialized with upstream '%s'. Instead found upstream '%s' for input '%s'", i, want, got, test.input)
}
}
}
}
}
}

53
test/kubernetes_test.go
View file

@ -62,6 +62,8 @@ var dnsTestCases = []test.Case{
test.A("svc-c.test-1.svc.cluster.local. 303 IN A 10.0.0.115"),
test.A("headless-svc.test-1.svc.cluster.local. 303 IN A 172.17.0.5"),
test.A("headless-svc.test-1.svc.cluster.local. 303 IN A 172.17.0.6"),
test.CNAME("ext-svc.test-1.svc.cluster.local. 0 IN CNAME example.net."),
test.A("example.net. 68974 IN A 13.14.15.16"),
},
},
{
@ -73,6 +75,8 @@ var dnsTestCases = []test.Case{
test.A("svc-c.test-1.svc.cluster.local. 303 IN A 10.0.0.115"),
test.A("headless-svc.test-1.svc.cluster.local. 303 IN A 172.17.0.5"),
test.A("headless-svc.test-1.svc.cluster.local. 303 IN A 172.17.0.6"),
test.CNAME("ext-svc.test-1.svc.cluster.local. 0 IN CNAME example.net."),
test.A("example.net. 68974 IN A 13.14.15.16"),
},
},
{
@ -94,6 +98,8 @@ var dnsTestCases = []test.Case{
test.A("svc-c.test-1.svc.cluster.local. 303 IN A 10.0.0.115"),
test.A("headless-svc.test-1.svc.cluster.local. 303 IN A 172.17.0.5"),
test.A("headless-svc.test-1.svc.cluster.local. 303 IN A 172.17.0.6"),
test.CNAME("ext-svc.test-1.svc.cluster.local. 0 IN CNAME example.net."),
test.A("example.net. 68974 IN A 13.14.15.16"),
},
},
{
@ -104,7 +110,6 @@ var dnsTestCases = []test.Case{
test.A("headless-svc.test-1.svc.cluster.local. 303 IN A 172.17.0.6"),
},
},
//TODO: Fix below to all use test.SRV not test.A!
{
Qname: "*._TcP.svc-1-a.test-1.svc.cluster.local.", Qtype: dns.TypeSRV,
Rcode: dns.RcodeSuccess,
@ -240,6 +245,21 @@ var dnsTestCases = []test.Case{
test.NS("cluster.local. 0 IN NS kubernetes.default.svc.cluster.local."),
},
},
{
Qname: "ext-svc.test-1.svc.cluster.local.", Qtype: dns.TypeA,
Rcode: dns.RcodeSuccess,
Answer: []dns.RR{
test.CNAME("ext-svc.test-1.svc.cluster.local. 0 IN CNAME example.net."),
test.A("example.net. 72031 IN A 13.14.15.16"),
},
},
{
Qname: "ext-svc.test-1.svc.cluster.local.", Qtype: dns.TypeCNAME,
Rcode: dns.RcodeSuccess,
Answer: []dns.RR{
test.CNAME("ext-svc.test-1.svc.cluster.local. 0 IN CNAME example.net."),
},
},
}
var dnsTestCasesPodsInsecure = []test.Case{
@ -444,13 +464,34 @@ func doIntegrationTests(t *testing.T, corefile string, testCases []test.Case) {
}
}
func createUpstreamServer(t *testing.T) (func(), *caddy.Instance, string) {
upfile, rmfile, err := TempFile(os.TempDir(), exampleNet)
if err != nil {
t.Fatalf("Could not create file for CNAME upstream lookups: %s", err)
}
upstreamServerCorefile := `.:0 {
file ` + upfile + ` example.net
erratic . {
drop 0
}
`
server, udp := createTestServer(t, upstreamServerCorefile)
return rmfile, server, udp
}
func TestKubernetesIntegration(t *testing.T) {
removeUpstreamConfig, upstreamServer, udp := createUpstreamServer(t)
defer upstreamServer.Stop()
defer removeUpstreamConfig()
corefile :=
`.:0 {
kubernetes cluster.local 0.0.10.in-addr.arpa {
endpoint http://localhost:8080
namespaces test-1
pods disabled
upstream ` + udp + `
}
erratic . {
drop 0
@ -530,6 +571,11 @@ func TestKubernetesIntegrationFallthrough(t *testing.T) {
t.Fatalf("Could not create TempFile for fallthrough: %s", err)
}
defer rmFunc()
removeUpstreamConfig, upstreamServer, udp := createUpstreamServer(t)
defer upstreamServer.Stop()
defer removeUpstreamConfig()
corefile :=
`.:0 {
file ` + dbfile + ` cluster.local
@ -537,6 +583,7 @@ func TestKubernetesIntegrationFallthrough(t *testing.T) {
endpoint http://localhost:8080
cidrs 10.0.0.0/24
namespaces test-1
upstream ` + udp + `
fallthrough
}
erratic {
@ -561,3 +608,7 @@ cname.cluster.local. IN CNAME www.example.net.
service.namespace.svc.cluster.local. IN SRV 8080 10 10 cluster.local.
`
const exampleNet = `; example.net. test file for cname tests
example.net. IN A 13.14.15.16
`