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-rw-r--r--core/dnsserver/zdirectives.go1
-rw-r--r--core/plugin/zplugin.go1
-rw-r--r--plugin.cfg1
-rw-r--r--plugin/k8s_external/OWNERS4
-rw-r--r--plugin/k8s_external/README.md78
-rw-r--r--plugin/k8s_external/apex.go110
-rw-r--r--plugin/k8s_external/apex_test.go105
-rw-r--r--plugin/k8s_external/external.go112
-rw-r--r--plugin/k8s_external/external_test.go210
-rw-r--r--plugin/k8s_external/msg_to_dns.go148
-rw-r--r--plugin/k8s_external/setup.go86
-rw-r--r--plugin/k8s_external/setup_test.go48
-rw-r--r--plugin/kubernetes/controller.go6
-rw-r--r--plugin/kubernetes/external.go92
-rw-r--r--plugin/kubernetes/external_test.go139
-rw-r--r--plugin/kubernetes/ns.go4
-rw-r--r--plugin/kubernetes/object/service.go12
17 files changed, 1156 insertions, 1 deletions
diff --git a/core/dnsserver/zdirectives.go b/core/dnsserver/zdirectives.go
index 280c03144..948deb33a 100644
--- a/core/dnsserver/zdirectives.go
+++ b/core/dnsserver/zdirectives.go
@@ -34,6 +34,7 @@ var Directives = []string{
"hosts",
"route53",
"federation",
+ "k8s_external",
"kubernetes",
"file",
"auto",
diff --git a/core/plugin/zplugin.go b/core/plugin/zplugin.go
index 397438663..6102d94bd 100644
--- a/core/plugin/zplugin.go
+++ b/core/plugin/zplugin.go
@@ -20,6 +20,7 @@ import (
_ "github.com/coredns/coredns/plugin/forward"
_ "github.com/coredns/coredns/plugin/health"
_ "github.com/coredns/coredns/plugin/hosts"
+ _ "github.com/coredns/coredns/plugin/k8s_external"
_ "github.com/coredns/coredns/plugin/kubernetes"
_ "github.com/coredns/coredns/plugin/loadbalance"
_ "github.com/coredns/coredns/plugin/log"
diff --git a/plugin.cfg b/plugin.cfg
index 6a8ad0ecd..fe6d7d023 100644
--- a/plugin.cfg
+++ b/plugin.cfg
@@ -43,6 +43,7 @@ template:template
hosts:hosts
route53:route53
federation:federation
+k8s_external:k8s_external
kubernetes:kubernetes
file:file
auto:auto
diff --git a/plugin/k8s_external/OWNERS b/plugin/k8s_external/OWNERS
new file mode 100644
index 000000000..eee46f686
--- /dev/null
+++ b/plugin/k8s_external/OWNERS
@@ -0,0 +1,4 @@
+reviewers:
+ - miekg
+approvers:
+ - miekg
diff --git a/plugin/k8s_external/README.md b/plugin/k8s_external/README.md
new file mode 100644
index 000000000..3cdf44849
--- /dev/null
+++ b/plugin/k8s_external/README.md
@@ -0,0 +1,78 @@
+# k8s_external
+
+## Name
+
+*k8s_external* - resolve load balancer and external IPs from outside kubernetes clusters.
+
+## Description
+
+This plugin allows an additional zone to resolve the external IP address(es) of a Kubernetes
+service. This plugin is only useful if the *kubernetes* plugin is also loaded.
+
+The plugin uses an external zone to resolve in-cluster IP addresses. It only handles queries for A,
+AAAA and SRV records, all others result in NODATA responses. To make it a proper DNS zone it handles
+SOA and NS queries for the apex of the zone.
+
+By default the apex of the zone will look like (assuming the zone used is `example.org`):
+
+~~~ dns
+example.org. 5 IN SOA ns1.dns.example.org. hostmaster.example.org. (
+ 12345 ; serial
+ 14400 ; refresh (4 hours)
+ 3600 ; retry (1 hour)
+ 604800 ; expire (1 week)
+ 5 ; minimum (4 hours)
+ )
+example.org 5 IN NS ns1.dns.example.org.
+
+ns1.dns.example.org. 5 IN A ....
+ns1.dns.example.org. 5 IN AAAA ....
+~~~
+
+Note we use the `dns` subdomain to place the records the DNS needs (see the `apex` directive). Also
+note the SOA's serial number is static. The IP addresses of the nameserver records are those of the
+CoreDNS service.
+
+The *k8s_external* plugin handles the subdomain `dns` and the apex of the zone by itself, all other
+queries are resolved to addresses in the cluster.
+
+## Syntax
+
+~~~
+k8s_external [ZONE...]
+~~~
+
+* **ZONES** zones *k8s_external* should be authoritative for.
+
+If you want to change the apex domain or use a different TTL for the return records you can use
+this extended syntax.
+
+~~~
+k8s_external [ZONE...] {
+ apex APEX
+ ttl TTL
+}
+~~~
+
+* **APEX** is the name (DNS label) to use the apex records, defaults to `dns`.
+* `ttl` allows you to set a custom **TTL** for responses. The default is 5 (seconds).
+
+# Examples
+
+Enable names under `example.org` to be resolved to in cluster DNS addresses.
+
+~~~
+. {
+ kubernetes cluster.local
+ k8s_external example.org
+}
+~~~
+
+# Also See
+
+For some background see [resolve external IP address](https://github.com/kubernetes/dns/issues/242).
+And [A records for services with Load Balancer IP](https://github.com/coredns/coredns/issues/1851).
+
+# Bugs
+
+PTR queries for the reverse zone is not supported.
diff --git a/plugin/k8s_external/apex.go b/plugin/k8s_external/apex.go
new file mode 100644
index 000000000..f58894817
--- /dev/null
+++ b/plugin/k8s_external/apex.go
@@ -0,0 +1,110 @@
+package external
+
+import (
+ "github.com/coredns/coredns/plugin/pkg/dnsutil"
+ "github.com/coredns/coredns/request"
+
+ "github.com/miekg/dns"
+)
+
+// serveApex serves request that hit the zone' apex. A reply is written back to the client.
+func (e *External) serveApex(state request.Request) (int, error) {
+ m := new(dns.Msg)
+ m.SetReply(state.Req)
+ switch state.QType() {
+ case dns.TypeSOA:
+ m.Answer = []dns.RR{e.soa(state)}
+ case dns.TypeNS:
+ m.Answer = []dns.RR{e.ns(state)}
+
+ addr := e.externalAddrFunc(state)
+ for _, rr := range addr {
+ rr.Header().Ttl = e.ttl
+ rr.Header().Name = state.QName()
+ m.Extra = append(m.Extra, rr)
+ }
+ default:
+ m.Ns = []dns.RR{e.soa(state)}
+ }
+
+ state.W.WriteMsg(m)
+ return 0, nil
+}
+
+// serveSubApex serves requests that hit the zones fake 'dns' subdomain where our nameservers live.
+func (e *External) serveSubApex(state request.Request) (int, error) {
+ base, _ := dnsutil.TrimZone(state.Name(), state.Zone)
+
+ m := new(dns.Msg)
+ m.SetReply(state.Req)
+
+ // base is either dns. of ns1.dns (or another name), if it's longer return nxdomain
+ switch labels := dns.CountLabel(base); labels {
+ default:
+ m.SetRcode(m, dns.RcodeNameError)
+ m.Ns = []dns.RR{e.soa(state)}
+ state.W.WriteMsg(m)
+ return 0, nil
+ case 2:
+ nl, _ := dns.NextLabel(base, 0)
+ ns := base[:nl]
+ if ns != "ns1." {
+ // nxdomain
+ m.SetRcode(m, dns.RcodeNameError)
+ m.Ns = []dns.RR{e.soa(state)}
+ state.W.WriteMsg(m)
+ return 0, nil
+ }
+
+ addr := e.externalAddrFunc(state)
+ for _, rr := range addr {
+ rr.Header().Ttl = e.ttl
+ rr.Header().Name = state.QName()
+ switch state.QType() {
+ case dns.TypeA:
+ if rr.Header().Rrtype == dns.TypeA {
+ m.Answer = append(m.Answer, rr)
+ }
+ case dns.TypeAAAA:
+ if rr.Header().Rrtype == dns.TypeAAAA {
+ m.Answer = append(m.Answer, rr)
+ }
+ }
+ }
+
+ if len(m.Answer) == 0 {
+ m.Ns = []dns.RR{e.soa(state)}
+ }
+
+ state.W.WriteMsg(m)
+ return 0, nil
+
+ case 1:
+ // nodata for the dns empty non-terminal
+ m.Ns = []dns.RR{e.soa(state)}
+ state.W.WriteMsg(m)
+ return 0, nil
+ }
+}
+
+func (e *External) soa(state request.Request) *dns.SOA {
+ header := dns.RR_Header{Name: state.Zone, Rrtype: dns.TypeSOA, Ttl: e.ttl, Class: dns.ClassINET}
+
+ soa := &dns.SOA{Hdr: header,
+ Mbox: dnsutil.Join(e.hostmaster, e.apex, state.Zone),
+ Ns: dnsutil.Join("ns1", e.apex, state.Zone),
+ Serial: 12345, // Also dynamic?
+ Refresh: 7200,
+ Retry: 1800,
+ Expire: 86400,
+ Minttl: e.ttl,
+ }
+ return soa
+}
+
+func (e *External) ns(state request.Request) *dns.NS {
+ header := dns.RR_Header{Name: state.Zone, Rrtype: dns.TypeNS, Ttl: e.ttl, Class: dns.ClassINET}
+ ns := &dns.NS{Hdr: header, Ns: dnsutil.Join("ns1", e.apex, state.Zone)}
+
+ return ns
+}
diff --git a/plugin/k8s_external/apex_test.go b/plugin/k8s_external/apex_test.go
new file mode 100644
index 000000000..e6b118d3d
--- /dev/null
+++ b/plugin/k8s_external/apex_test.go
@@ -0,0 +1,105 @@
+package external
+
+import (
+ "context"
+ "testing"
+
+ "github.com/coredns/coredns/plugin/kubernetes"
+ "github.com/coredns/coredns/plugin/pkg/dnstest"
+ "github.com/coredns/coredns/plugin/test"
+
+ "github.com/miekg/dns"
+)
+
+func TestApex(t *testing.T) {
+ k := kubernetes.New([]string{"cluster.local."})
+ k.Namespaces = map[string]struct{}{"testns": struct{}{}}
+ k.APIConn = &external{}
+
+ e := New()
+ e.Zones = []string{"example.com."}
+ e.Next = test.NextHandler(dns.RcodeSuccess, nil)
+ e.externalFunc = k.External
+ e.externalAddrFunc = externalAddress // internal test function
+
+ ctx := context.TODO()
+ for i, tc := range testsApex {
+ r := tc.Msg()
+ w := dnstest.NewRecorder(&test.ResponseWriter{})
+
+ _, err := e.ServeDNS(ctx, w, r)
+ if err != tc.Error {
+ t.Errorf("Test %d expected no error, got %v", i, err)
+ return
+ }
+ if tc.Error != nil {
+ continue
+ }
+
+ resp := w.Msg
+ if resp == nil {
+ t.Fatalf("Test %d, got nil message and no error for %q", i, r.Question[0].Name)
+ }
+ test.SortAndCheck(t, resp, tc)
+ }
+}
+
+var testsApex = []test.Case{
+ {
+ Qname: "example.com.", Qtype: dns.TypeSOA, Rcode: dns.RcodeSuccess,
+ Answer: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+ {
+ Qname: "example.com.", Qtype: dns.TypeNS, Rcode: dns.RcodeSuccess,
+ Answer: []dns.RR{
+ test.NS("example.com. 5 IN NS ns1.dns.example.com."),
+ },
+ Extra: []dns.RR{
+ test.A("example.com. 5 IN A 127.0.0.1"),
+ },
+ },
+ {
+ Qname: "example.com.", Qtype: dns.TypeSRV, Rcode: dns.RcodeSuccess,
+ Ns: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+ {
+ Qname: "dns.example.com.", Qtype: dns.TypeSRV, Rcode: dns.RcodeSuccess,
+ Ns: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+ {
+ Qname: "dns.example.com.", Qtype: dns.TypeNS, Rcode: dns.RcodeSuccess,
+ Ns: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+ {
+ Qname: "ns1.dns.example.com.", Qtype: dns.TypeSRV, Rcode: dns.RcodeSuccess,
+ Ns: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+ {
+ Qname: "ns1.dns.example.com.", Qtype: dns.TypeNS, Rcode: dns.RcodeSuccess,
+ Ns: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+ {
+ Qname: "ns1.dns.example.com.", Qtype: dns.TypeAAAA, Rcode: dns.RcodeSuccess,
+ Ns: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+ {
+ Qname: "ns1.dns.example.com.", Qtype: dns.TypeA, Rcode: dns.RcodeSuccess,
+ Answer: []dns.RR{
+ test.A("ns1.dns.example.com. 5 IN A 127.0.0.1"),
+ },
+ },
+}
diff --git a/plugin/k8s_external/external.go b/plugin/k8s_external/external.go
new file mode 100644
index 000000000..3ca188ed8
--- /dev/null
+++ b/plugin/k8s_external/external.go
@@ -0,0 +1,112 @@
+/*
+Package external implements external names for kubernetes clusters.
+
+This plugin only handles three qtypes (except the apex queries, because those are handled
+differently). We support A, AAAA and SRV request, for all other types we return NODATA or
+NXDOMAIN depending on the state of the cluster.
+
+A plugin willing to provide these services must implement the Externaler interface, although it
+likely only makes sense for the *kubernetes* plugin.
+
+*/
+package external
+
+import (
+ "context"
+
+ "github.com/coredns/coredns/plugin"
+ "github.com/coredns/coredns/plugin/etcd/msg"
+ "github.com/coredns/coredns/request"
+
+ "github.com/miekg/dns"
+)
+
+// Externaler defines the interface that a plugin should implement in order to be used by External.
+type Externaler interface {
+ // External returns a slice of msg.Services that are looked up in the backend and match
+ // the request.
+ External(request.Request) ([]msg.Service, int)
+ // ExternalAddress should return a string slice of addresses for the nameserving endpoint.
+ ExternalAddress(state request.Request) []dns.RR
+}
+
+// External resolves Ingress and Loadbalance IPs from kubernetes clusters.
+type External struct {
+ Next plugin.Handler
+ Zones []string
+
+ hostmaster string
+ apex string
+ ttl uint32
+
+ externalFunc func(request.Request) ([]msg.Service, int)
+ externalAddrFunc func(request.Request) []dns.RR
+}
+
+// New returns a new and initialized *External.
+func New() *External {
+ e := &External{hostmaster: "hostmaster", ttl: 5, apex: "dns"}
+ return e
+}
+
+// ServeDNS implements the plugin.Handle interface.
+func (e *External) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
+ state := request.Request{W: w, Req: r}
+
+ zone := plugin.Zones(e.Zones).Matches(state.Name())
+ if zone == "" {
+ return plugin.NextOrFailure(e.Name(), e.Next, ctx, w, r)
+ }
+
+ if e.externalFunc == nil {
+ return plugin.NextOrFailure(e.Name(), e.Next, ctx, w, r)
+ }
+
+ state.Zone = zone
+ for _, z := range e.Zones {
+ // TODO(miek): save this in the External struct.
+ if state.Name() == z { // apex query
+ ret, err := e.serveApex(state)
+ return ret, err
+ }
+ if dns.IsSubDomain(e.apex+"."+z, state.Name()) {
+ // dns subdomain test for ns. and dns. queries
+ ret, err := e.serveSubApex(state)
+ return ret, err
+ }
+ }
+
+ svc, rcode := e.externalFunc(state)
+
+ m := new(dns.Msg)
+ m.SetReply(state.Req)
+
+ if len(svc) == 0 {
+ m.Rcode = rcode
+ m.Ns = []dns.RR{e.soa(state)}
+ w.WriteMsg(m)
+ return 0, nil
+ }
+
+ switch state.QType() {
+ case dns.TypeA:
+ m.Answer = e.a(svc, state)
+ case dns.TypeAAAA:
+ m.Answer = e.aaaa(svc, state)
+ case dns.TypeSRV:
+ m.Answer, m.Extra = e.srv(svc, state)
+ default:
+ m.Ns = []dns.RR{e.soa(state)}
+ }
+
+ // If we did have records, but queried for the wrong qtype return a nodata response.
+ if len(m.Answer) == 0 {
+ m.Ns = []dns.RR{e.soa(state)}
+ }
+
+ w.WriteMsg(m)
+ return 0, nil
+}
+
+// Name implements the Handler interface.
+func (e *External) Name() string { return "k8s_external" }
diff --git a/plugin/k8s_external/external_test.go b/plugin/k8s_external/external_test.go
new file mode 100644
index 000000000..257a7802b
--- /dev/null
+++ b/plugin/k8s_external/external_test.go
@@ -0,0 +1,210 @@
+package external
+
+import (
+ "context"
+ "testing"
+
+ "github.com/coredns/coredns/plugin/kubernetes"
+ "github.com/coredns/coredns/plugin/kubernetes/object"
+ "github.com/coredns/coredns/plugin/pkg/dnstest"
+ "github.com/coredns/coredns/plugin/pkg/watch"
+ "github.com/coredns/coredns/plugin/test"
+ "github.com/coredns/coredns/request"
+
+ "github.com/miekg/dns"
+ api "k8s.io/api/core/v1"
+ meta "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+func TestExternal(t *testing.T) {
+ k := kubernetes.New([]string{"cluster.local."})
+ k.Namespaces = map[string]struct{}{"testns": struct{}{}}
+ k.APIConn = &external{}
+
+ e := New()
+ e.Zones = []string{"example.com."}
+ e.Next = test.NextHandler(dns.RcodeSuccess, nil)
+ e.externalFunc = k.External
+ e.externalAddrFunc = externalAddress // internal test function
+
+ ctx := context.TODO()
+ for i, tc := range tests {
+ r := tc.Msg()
+ w := dnstest.NewRecorder(&test.ResponseWriter{})
+
+ _, err := e.ServeDNS(ctx, w, r)
+ if err != tc.Error {
+ t.Errorf("Test %d expected no error, got %v", i, err)
+ return
+ }
+ if tc.Error != nil {
+ continue
+ }
+
+ resp := w.Msg
+ if resp == nil {
+ t.Fatalf("Test %d, got nil message and no error for %q", i, r.Question[0].Name)
+ }
+ test.SortAndCheck(t, resp, tc)
+ }
+}
+
+var tests = []test.Case{
+ // A Service
+ {
+ Qname: "svc1.testns.example.com.", Qtype: dns.TypeA, Rcode: dns.RcodeSuccess,
+ Answer: []dns.RR{
+ test.A("svc1.testns.example.com. 5 IN A 1.2.3.4"),
+ },
+ },
+ {
+ Qname: "svc1.testns.example.com.", Qtype: dns.TypeSRV, Rcode: dns.RcodeSuccess,
+ Answer: []dns.RR{test.SRV("svc1.testns.example.com. 5 IN SRV 0 100 80 svc1.testns.example.com.")},
+ Extra: []dns.RR{test.A("svc1.testns.example.com. 5 IN A 1.2.3.4")},
+ },
+ // SRV Service Not udp/tcp
+ {
+ Qname: "*._not-udp-or-tcp.svc1.testns.example.com.", Qtype: dns.TypeSRV, Rcode: dns.RcodeNameError,
+ Ns: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+ // SRV Service
+ {
+ Qname: "_http._tcp.svc1.testns.example.com.", Qtype: dns.TypeSRV, Rcode: dns.RcodeSuccess,
+ Answer: []dns.RR{
+ test.SRV("_http._tcp.svc1.testns.example.com. 5 IN SRV 0 100 80 svc1.testns.example.com."),
+ },
+ Extra: []dns.RR{
+ test.A("svc1.testns.example.com. 5 IN A 1.2.3.4"),
+ },
+ },
+ // AAAA Service (with an existing A record, but no AAAA record)
+ {
+ Qname: "svc1.testns.example.com.", Qtype: dns.TypeAAAA, Rcode: dns.RcodeSuccess,
+ Ns: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+ // AAAA Service (non-existing service)
+ {
+ Qname: "svc0.testns.example.com.", Qtype: dns.TypeAAAA, Rcode: dns.RcodeNameError,
+ Ns: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+ // A Service (non-existing service)
+ {
+ Qname: "svc0.testns.example.com.", Qtype: dns.TypeA, Rcode: dns.RcodeNameError,
+ Ns: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+ // A Service (non-existing namespace)
+ {
+ Qname: "svc0.svc-nons.example.com.", Qtype: dns.TypeA, Rcode: dns.RcodeNameError,
+ Ns: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+ // AAAA Service
+ {
+ Qname: "svc6.testns.example.com.", Qtype: dns.TypeAAAA, Rcode: dns.RcodeSuccess,
+ Answer: []dns.RR{
+ test.AAAA("svc6.testns.example.com. 5 IN AAAA 1:2::5"),
+ },
+ },
+ // SRV
+ {
+ Qname: "_http._tcp.svc6.testns.example.com.", Qtype: dns.TypeSRV, Rcode: dns.RcodeSuccess,
+ Answer: []dns.RR{
+ test.SRV("_http._tcp.svc6.testns.example.com. 5 IN SRV 0 100 80 svc6.testns.example.com."),
+ },
+ Extra: []dns.RR{
+ test.AAAA("svc6.testns.example.com. 5 IN AAAA 1:2::5"),
+ },
+ },
+ // SRV
+ {
+ Qname: "svc6.testns.example.com.", Qtype: dns.TypeSRV, Rcode: dns.RcodeSuccess,
+ Answer: []dns.RR{
+ test.SRV("svc6.testns.example.com. 5 IN SRV 0 100 80 svc6.testns.example.com."),
+ },
+ Extra: []dns.RR{
+ test.AAAA("svc6.testns.example.com. 5 IN AAAA 1:2::5"),
+ },
+ },
+ {
+ Qname: "testns.example.com.", Qtype: dns.TypeA, Rcode: dns.RcodeSuccess,
+ Ns: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+ {
+ Qname: "testns.example.com.", Qtype: dns.TypeSOA, Rcode: dns.RcodeSuccess,
+ Ns: []dns.RR{
+ test.SOA("example.com. 5 IN SOA ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+ },
+ },
+}
+
+type external struct{}
+
+func (external) HasSynced() bool { return true }
+func (external) Run() { return }
+func (external) Stop() error { return nil }
+func (external) EpIndexReverse(string) []*object.Endpoints { return nil }
+func (external) SvcIndexReverse(string) []*object.Service { return nil }
+func (external) Modified() int64 { return 0 }
+func (external) SetWatchChan(watch.Chan) {}
+func (external) Watch(string) error { return nil }
+func (external) StopWatching(string) {}
+func (external) EpIndex(s string) []*object.Endpoints { return nil }
+func (external) EndpointsList() []*object.Endpoints { return nil }
+func (external) GetNodeByName(name string) (*api.Node, error) { return nil, nil }
+func (external) SvcIndex(s string) []*object.Service { return svcIndexExternal[s] }
+func (external) PodIndex(string) []*object.Pod { return nil }
+
+func (external) GetNamespaceByName(name string) (*api.Namespace, error) {
+ return &api.Namespace{
+ ObjectMeta: meta.ObjectMeta{
+ Name: name,
+ },
+ }, nil
+}
+
+var svcIndexExternal = map[string][]*object.Service{
+ "svc1.testns": {
+ {
+ Name: "svc1",
+ Namespace: "testns",
+ Type: api.ServiceTypeClusterIP,
+ ClusterIP: "10.0.0.1",
+ ExternalIPs: []string{"1.2.3.4"},
+ Ports: []api.ServicePort{{Name: "http", Protocol: "tcp", Port: 80}},
+ },
+ },
+ "svc6.testns": {
+ {
+ Name: "svc6",
+ Namespace: "testns",
+ Type: api.ServiceTypeClusterIP,
+ ClusterIP: "10.0.0.3",
+ ExternalIPs: []string{"1:2::5"},
+ Ports: []api.ServicePort{{Name: "http", Protocol: "tcp", Port: 80}},
+ },
+ },
+}
+
+func (external) ServiceList() []*object.Service {
+ var svcs []*object.Service
+ for _, svc := range svcIndexExternal {
+ svcs = append(svcs, svc...)
+ }
+ return svcs
+}
+
+func externalAddress(state request.Request) []dns.RR {
+ a := test.A("example.org. IN A 127.0.0.1")
+ return []dns.RR{a}
+}
diff --git a/plugin/k8s_external/msg_to_dns.go b/plugin/k8s_external/msg_to_dns.go
new file mode 100644
index 000000000..d09229d48
--- /dev/null
+++ b/plugin/k8s_external/msg_to_dns.go
@@ -0,0 +1,148 @@
+package external
+
+import (
+ "math"
+
+ "github.com/coredns/coredns/plugin/etcd/msg"
+ "github.com/coredns/coredns/request"
+
+ "github.com/miekg/dns"
+)
+
+func (e *External) a(services []msg.Service, state request.Request) (records []dns.RR) {
+ dup := make(map[string]struct{})
+
+ for _, s := range services {
+
+ what, ip := s.HostType()
+
+ switch what {
+ case dns.TypeCNAME:
+ // can't happen
+
+ case dns.TypeA:
+ if _, ok := dup[s.Host]; !ok {
+ dup[s.Host] = struct{}{}
+ rr := s.NewA(state.QName(), ip)
+ rr.Hdr.Ttl = e.ttl
+ records = append(records, rr)
+ }
+
+ case dns.TypeAAAA:
+ // nada
+ }
+ }
+ return records
+}
+
+func (e *External) aaaa(services []msg.Service, state request.Request) (records []dns.RR) {
+ dup := make(map[string]struct{})
+
+ for _, s := range services {
+
+ what, ip := s.HostType()
+
+ switch what {
+ case dns.TypeCNAME:
+ // can't happen
+
+ case dns.TypeA:
+ // nada
+
+ case dns.TypeAAAA:
+ if _, ok := dup[s.Host]; !ok {
+ dup[s.Host] = struct{}{}
+ rr := s.NewAAAA(state.QName(), ip)
+ rr.Hdr.Ttl = e.ttl
+ records = append(records, rr)
+ }
+ }
+ }
+ return records
+}
+
+func (e *External) srv(services []msg.Service, state request.Request) (records, extra []dns.RR) {
+ dup := make(map[item]struct{})
+
+ // Looping twice to get the right weight vs priority. This might break because we may drop duplicate SRV records latter on.
+ w := make(map[int]int)
+ for _, s := range services {
+ weight := 100
+ if s.Weight != 0 {
+ weight = s.Weight
+ }
+ if _, ok := w[s.Priority]; !ok {
+ w[s.Priority] = weight
+ continue
+ }
+ w[s.Priority] += weight
+ }
+ for _, s := range services {
+ // Don't add the entry if the port is -1 (invalid). The kubernetes plugin uses port -1 when a service/endpoint
+ // does not have any declared ports.
+ if s.Port == -1 {
+ continue
+ }
+ w1 := 100.0 / float64(w[s.Priority])
+ if s.Weight == 0 {
+ w1 *= 100
+ } else {
+ w1 *= float64(s.Weight)
+ }
+ weight := uint16(math.Floor(w1))
+
+ what, ip := s.HostType()
+
+ switch what {
+ case dns.TypeCNAME:
+ // can't happen
+
+ case dns.TypeA, dns.TypeAAAA:
+ addr := s.Host
+ s.Host = msg.Domain(s.Key)
+ srv := s.NewSRV(state.QName(), weight)
+
+ if ok := isDuplicate(dup, srv.Target, "", srv.Port); !ok {
+ records = append(records, srv)
+ }
+
+ if ok := isDuplicate(dup, srv.Target, addr, 0); !ok {
+ hdr := dns.RR_Header{Name: srv.Target, Rrtype: what, Class: dns.ClassINET, Ttl: e.ttl}
+
+ switch what {
+ case dns.TypeA:
+ extra = append(extra, &dns.A{Hdr: hdr, A: ip})
+ case dns.TypeAAAA:
+ extra = append(extra, &dns.AAAA{Hdr: hdr, AAAA: ip})
+ }
+ }
+ }
+ }
+ return records, extra
+}
+
+// not sure if this is even needed.
+
+// item holds records.
+type item struct {
+ name string // name of the record (either owner or something else unique).
+ port uint16 // port of the record (used for address records, A and AAAA).
+ addr string // address of the record (A and AAAA).
+}
+
+// isDuplicate uses m to see if the combo (name, addr, port) already exists. If it does
+// not exist already IsDuplicate will also add the record to the map.
+func isDuplicate(m map[item]struct{}, name, addr string, port uint16) bool {
+ if addr != "" {
+ _, ok := m[item{name, 0, addr}]
+ if !ok {
+ m[item{name, 0, addr}] = struct{}{}
+ }
+ return ok
+ }
+ _, ok := m[item{name, port, ""}]
+ if !ok {
+ m[item{name, port, ""}] = struct{}{}
+ }
+ return ok
+}
diff --git a/plugin/k8s_external/setup.go b/plugin/k8s_external/setup.go
new file mode 100644
index 000000000..ede34c6ce
--- /dev/null
+++ b/plugin/k8s_external/setup.go
@@ -0,0 +1,86 @@
+package external
+
+import (
+ "strconv"
+
+ "github.com/coredns/coredns/core/dnsserver"
+ "github.com/coredns/coredns/plugin"
+
+ "github.com/mholt/caddy"
+)
+
+func init() {
+ caddy.RegisterPlugin("k8s_external", caddy.Plugin{
+ ServerType: "dns",
+ Action: setup,
+ })
+}
+
+func setup(c *caddy.Controller) error {
+ e, err := parse(c)
+ if err != nil {
+ return plugin.Error("k8s_external", err)
+ }
+
+ // Do this in OnStartup, so all plugins have been initialized.
+ c.OnStartup(func() error {
+ m := dnsserver.GetConfig(c).Handler("kubernetes")
+ if m == nil {
+ return nil
+ }
+ if x, ok := m.(Externaler); ok {
+ e.externalFunc = x.External
+ e.externalAddrFunc = x.ExternalAddress
+ }
+ return nil
+ })
+
+ dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
+ e.Next = next
+ return e
+ })
+
+ return nil
+}
+
+func parse(c *caddy.Controller) (*External, error) {
+ e := New()
+
+ for c.Next() { // external
+ zones := c.RemainingArgs()
+ e.Zones = zones
+ if len(zones) == 0 {
+ e.Zones = make([]string, len(c.ServerBlockKeys))
+ copy(e.Zones, c.ServerBlockKeys)
+ }
+ for i, str := range e.Zones {
+ e.Zones[i] = plugin.Host(str).Normalize()
+ }
+ for c.NextBlock() {
+ switch c.Val() {
+ case "ttl":
+ args := c.RemainingArgs()
+ if len(args) == 0 {
+ return nil, c.ArgErr()
+ }
+ t, err := strconv.Atoi(args[0])
+ if err != nil {
+ return nil, err
+ }
+ if t < 0 || t > 3600 {
+ return nil, c.Errf("ttl must be in range [0, 3600]: %d", t)
+ }
+ e.ttl = uint32(t)
+ case "apex":
+ args := c.RemainingArgs()
+ if len(args) == 0 {
+ return nil, c.ArgErr()
+ }
+ e.apex = args[0]
+ default:
+ return nil, c.Errf("unknown property '%s'", c.Val())
+ }
+ }
+ }
+ return e, nil
+}
diff --git a/plugin/k8s_external/setup_test.go b/plugin/k8s_external/setup_test.go
new file mode 100644
index 000000000..4533e13ec
--- /dev/null
+++ b/plugin/k8s_external/setup_test.go
@@ -0,0 +1,48 @@
+package external
+
+import (
+ "testing"
+
+ "github.com/mholt/caddy"
+)
+
+func TestSetup(t *testing.T) {
+ tests := []struct {
+ input string
+ shouldErr bool
+ expectedZone string
+ expectedApex string
+ }{
+ {`k8s_external`, false, "", "dns"},
+ {`k8s_external example.org`, false, "example.org.", "dns"},
+ {`k8s_external example.org {
+ apex testdns
+}`, false, "example.org.", "testdns"},
+ }
+
+ for i, test := range tests {
+ c := caddy.NewTestController("dns", test.input)
+ e, err := parse(c)
+
+ if test.shouldErr && err == nil {
+ t.Errorf("Test %d: Expected error but found %s for input %s", i, err, test.input)
+ }
+
+ if err != nil {
+ if !test.shouldErr {
+ t.Errorf("Test %d: Expected no error but found one for input %s. Error was: %v", i, test.input, err)
+ }
+ }
+
+ if !test.shouldErr && test.expectedZone != "" {
+ if test.expectedZone != e.Zones[0] {
+ t.Errorf("Test %d, expected zone %q for input %s, got: %q", i, test.expectedZone, test.input, e.Zones[0])
+ }
+ }
+ if !test.shouldErr {
+ if test.expectedApex != e.apex {
+ t.Errorf("Test %d, expected apex %q for input %s, got: %q", i, test.expectedApex, test.input, e.apex)
+ }
+ }
+ }
+}
diff --git a/plugin/kubernetes/controller.go b/plugin/kubernetes/controller.go
index df90fcf82..9a2e9994a 100644
--- a/plugin/kubernetes/controller.go
+++ b/plugin/kubernetes/controller.go
@@ -172,7 +172,11 @@ func svcIPIndexFunc(obj interface{}) ([]string, error) {
if !ok {
return nil, errObj
}
- return []string{svc.ClusterIP}, nil
+ if len(svc.ExternalIPs) == 0 {
+ return []string{svc.ClusterIP}, nil
+ }
+
+ return append([]string{svc.ClusterIP}, svc.ExternalIPs...), nil
}
func svcNameNamespaceIndexFunc(obj interface{}) ([]string, error) {
diff --git a/plugin/kubernetes/external.go b/plugin/kubernetes/external.go
new file mode 100644
index 000000000..1770872b3
--- /dev/null
+++ b/plugin/kubernetes/external.go
@@ -0,0 +1,92 @@
+package kubernetes
+
+import (
+ "strings"
+
+ "github.com/coredns/coredns/plugin/etcd/msg"
+ "github.com/coredns/coredns/plugin/kubernetes/object"
+ "github.com/coredns/coredns/plugin/pkg/dnsutil"
+ "github.com/coredns/coredns/request"
+
+ "github.com/miekg/dns"
+)
+
+// External implements the ExternalFunc call from the external plugin.
+// It returns any services matching in the services' ExternalIPs.
+func (k *Kubernetes) External(state request.Request) ([]msg.Service, int) {
+ base, _ := dnsutil.TrimZone(state.Name(), state.Zone)
+
+ segs := dns.SplitDomainName(base)
+ last := len(segs) - 1
+ if last < 0 {
+ return nil, dns.RcodeServerFailure
+ }
+ // We dealing with a fairly normal domain name here, but; we still need to have the service
+ // and the namespace:
+ // service.namespace.<base>
+ //
+ // for service (and SRV) you can also say _tcp, and port (i.e. _http), we need those be picked
+ // up, unless they are not specified, then we use an internal wildcard.
+ port := "*"
+ protocol := "*"
+ namespace := segs[last]
+ if !k.namespaceExposed(namespace) || !k.namespace(namespace) {
+ return nil, dns.RcodeNameError
+ }
+
+ last--
+ if last < 0 {
+ return nil, dns.RcodeSuccess
+ }
+
+ service := segs[last]
+ last--
+ if last == 1 {
+ protocol = stripUnderscore(segs[last])
+ port = stripUnderscore(segs[last-1])
+ last -= 2
+ }
+
+ if last != -1 {
+ // too long
+ return nil, dns.RcodeNameError
+ }
+
+ idx := object.ServiceKey(service, namespace)
+ serviceList := k.APIConn.SvcIndex(idx)
+
+ services := []msg.Service{}
+ zonePath := msg.Path(state.Zone, coredns)
+ rcode := dns.RcodeNameError
+
+ for _, svc := range serviceList {
+ if namespace != svc.Namespace {
+ continue
+ }
+ if service != svc.Name {
+ continue
+ }
+
+ for _, ip := range svc.ExternalIPs {
+ for _, p := range svc.Ports {
+ if !(match(port, p.Name) && match(protocol, string(p.Protocol))) {
+ continue
+ }
+ rcode = dns.RcodeSuccess
+ s := msg.Service{Host: ip, Port: int(p.Port), TTL: k.ttl}
+ s.Key = strings.Join([]string{zonePath, svc.Namespace, svc.Name}, "/")
+
+ services = append(services, s)
+ }
+ }
+ }
+ return services, rcode
+}
+
+// ExternalAddress returns the external service address(es) for the CoreDNS service.
+func (k *Kubernetes) ExternalAddress(state request.Request) []dns.RR {
+ // This is probably wrong, because of all the fallback behavior of k.nsAddr, i.e. can get
+ // an address that isn't reacheable from outside the cluster.
+ rrs := []dns.RR{k.nsAddr()}
+ return rrs
+}
diff --git a/plugin/kubernetes/external_test.go b/plugin/kubernetes/external_test.go
new file mode 100644
index 000000000..7fb5469e1
--- /dev/null
+++ b/plugin/kubernetes/external_test.go
@@ -0,0 +1,139 @@
+package kubernetes
+
+import (
+ "testing"
+
+ "github.com/coredns/coredns/plugin/etcd/msg"
+ "github.com/coredns/coredns/plugin/kubernetes/object"
+ "github.com/coredns/coredns/plugin/pkg/watch"
+ "github.com/coredns/coredns/plugin/test"
+ "github.com/coredns/coredns/request"
+
+ "github.com/miekg/dns"
+ api "k8s.io/api/core/v1"
+ meta "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+var extCases = []struct {
+ Qname string
+ Qtype uint16
+ Msg []msg.Service
+ Rcode int
+}{
+ {
+ Qname: "svc1.testns.example.org.", Rcode: dns.RcodeSuccess,
+ Msg: []msg.Service{
+ msg.Service{Host: "1.2.3.4", Port: 80, TTL: 5, Key: "/c/org/example/testns/svc1"},
+ },
+ },
+ {
+ Qname: "svc6.testns.example.org.", Rcode: dns.RcodeSuccess,
+ Msg: []msg.Service{
+ msg.Service{Host: "1:2::5", Port: 80, TTL: 5, Key: "/c/org/example/testns/svc1"},
+ },
+ },
+ {
+ Qname: "*._not-udp-or-tcp.svc1.testns.example.com.", Rcode: dns.RcodeSuccess,
+ },
+ {
+ Qname: "_http._tcp.svc1.testns.example.com.", Rcode: dns.RcodeSuccess,
+ Msg: []msg.Service{
+ msg.Service{Host: "1.2.3.4", Port: 80, TTL: 5, Key: "/c/org/example/testns/svc1"},
+ },
+ },
+ {
+ Qname: "svc0.testns.example.com.", Rcode: dns.RcodeNameError,
+ },
+ {
+ Qname: "svc0.svc-nons.example.com.", Rcode: dns.RcodeNameError,
+ },
+}
+
+func TestExternal(t *testing.T) {
+ k := New([]string{"cluster.local."})
+ k.APIConn = &external{}
+ k.Next = test.NextHandler(dns.RcodeSuccess, nil)
+ k.Namespaces = map[string]struct{}{"testns": struct{}{}}
+
+ for i, tc := range extCases {
+ state := testRequest(tc.Qname)
+
+ svc, rcode := k.External(state)
+
+ if x := tc.Rcode; x != rcode {
+ t.Errorf("Test %d, expected rcode %d, got %d\n", i, x, rcode)
+ }
+
+ if len(svc) != len(tc.Msg) {
+ t.Errorf("Test %d, expected %d for messages, got %d\n", i, len(tc.Msg), len(svc))
+ }
+
+ for j, s := range svc {
+ if x := tc.Msg[j].Key; x != s.Key {
+ t.Errorf("Test %d, expected key %s, got %s\n", i, x, s.Key)
+ }
+ return
+ }
+ }
+}
+
+type external struct{}
+
+func (external) HasSynced() bool { return true }
+func (external) Run() { return }
+func (external) Stop() error { return nil }
+func (external) EpIndexReverse(string) []*object.Endpoints { return nil }
+func (external) SvcIndexReverse(string) []*object.Service { return nil }
+func (external) Modified() int64 { return 0 }
+func (external) SetWatchChan(watch.Chan) {}
+func (external) Watch(string) error { return nil }
+func (external) StopWatching(string) {}
+func (external) EpIndex(s string) []*object.Endpoints { return nil }
+func (external) EndpointsList() []*object.Endpoints { return nil }
+func (external) GetNodeByName(name string) (*api.Node, error) { return nil, nil }
+func (external) SvcIndex(s string) []*object.Service { return svcIndexExternal[s] }
+func (external) PodIndex(string) []*object.Pod { return nil }
+
+func (external) GetNamespaceByName(name string) (*api.Namespace, error) {
+ return &api.Namespace{
+ ObjectMeta: meta.ObjectMeta{
+ Name: name,
+ },
+ }, nil
+}
+
+var svcIndexExternal = map[string][]*object.Service{
+ "svc1.testns": {
+ {
+ Name: "svc1",
+ Namespace: "testns",
+ Type: api.ServiceTypeClusterIP,
+ ClusterIP: "10.0.0.1",
+ ExternalIPs: []string{"1.2.3.4"},
+ Ports: []api.ServicePort{{Name: "http", Protocol: "tcp", Port: 80}},
+ },
+ },
+ "svc6.testns": {
+ {
+ Name: "svc6",
+ Namespace: "testns",
+ Type: api.ServiceTypeClusterIP,
+ ClusterIP: "10.0.0.3",
+ ExternalIPs: []string{"1:2::5"},
+ Ports: []api.ServicePort{{Name: "http", Protocol: "tcp", Port: 80}},
+ },
+ },
+}
+
+func (external) ServiceList() []*object.Service {
+ var svcs []*object.Service
+ for _, svc := range svcIndexExternal {
+ svcs = append(svcs, svc...)
+ }
+ return svcs
+}
+
+func testRequest(name string) request.Request {
+ m := new(dns.Msg).SetQuestion(name, dns.TypeA)
+ return request.Request{W: &test.ResponseWriter{}, Req: m, Zone: "example.org."}
+}
diff --git a/plugin/kubernetes/ns.go b/plugin/kubernetes/ns.go
index 2ccb51ef3..f3d33ee22 100644
--- a/plugin/kubernetes/ns.go
+++ b/plugin/kubernetes/ns.go
@@ -12,6 +12,10 @@ func isDefaultNS(name, zone string) bool {
return strings.Index(name, defaultNSName) == 0 && strings.Index(name, zone) == len(defaultNSName)
}
+// nsAddr return the A record for the CoreDNS service in the cluster. If it fails that it fallsback
+// on the local address of the machine we're running on.
+//
+// This function is rather expensive to run.
func (k *Kubernetes) nsAddr() *dns.A {
var (
svcName string
diff --git a/plugin/kubernetes/object/service.go b/plugin/kubernetes/object/service.go
index be010e96b..af9a42b48 100644
--- a/plugin/kubernetes/object/service.go
+++ b/plugin/kubernetes/object/service.go
@@ -16,6 +16,9 @@ type Service struct {
ExternalName string
Ports []api.ServicePort
+ // ExternalIPs we may want to export.
+ ExternalIPs []string
+
*Empty
}
@@ -37,6 +40,8 @@ func ToService(obj interface{}) interface{} {
ClusterIP: svc.Spec.ClusterIP,
Type: svc.Spec.Type,
ExternalName: svc.Spec.ExternalName,
+
+ ExternalIPs: make([]string, len(svc.Status.LoadBalancer.Ingress)+len(svc.Spec.ExternalIPs)),
}
if len(svc.Spec.Ports) == 0 {
@@ -47,6 +52,11 @@ func ToService(obj interface{}) interface{} {
copy(s.Ports, svc.Spec.Ports)
}
+ li := copy(s.ExternalIPs, svc.Spec.ExternalIPs)
+ for i, lb := range svc.Status.LoadBalancer.Ingress {
+ s.ExternalIPs[li+i] = lb.IP
+ }
+
*svc = api.Service{}
return s
@@ -65,8 +75,10 @@ func (s *Service) DeepCopyObject() runtime.Object {
Type: s.Type,
ExternalName: s.ExternalName,
Ports: make([]api.ServicePort, len(s.Ports)),
+ ExternalIPs: make([]string, len(s.ExternalIPs)),
}
copy(s1.Ports, s.Ports)
+ copy(s1.ExternalIPs, s.ExternalIPs)
return s1
}
generated by cgit v1.2.3 (git 2.39.1) at 2025-07-21 21:58:01 +0000