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Update kubernetai plugin to support transfers via the transfers plugi…
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…n. (#66)

Abstract the list of kubernetes plugins to an interface so that we can affectively mock them and control per plugin behaviour and responses.

Signed-off-by: Dave McCormick <d_mccormick@apple.com>
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davidmccormick authored Sep 17, 2024
1 parent ce45312 commit 6304267
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Showing 6 changed files with 273 additions and 54 deletions.
145 changes: 145 additions & 0 deletions plugin/kubernetai/axfr_test.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,145 @@
package kubernetai

import (
"strings"
"testing"

"github.com/coredns/coredns/plugin/transfer"

"github.com/miekg/dns"
)

func TestKubernetesTransferNonAuthZone(t *testing.T) {
type fields struct {
name string
kubernetes []*mockK8sPlugin
zone string
serial uint32
expectedZone string
expectedError error
}
tests := []fields{
{
name: "TestSingleKubernetesTransferNonAuthZone",
kubernetes: []*mockK8sPlugin{
{
zones: []string{"cluster.local"},
transferErr: transfer.ErrNotAuthoritative,
},
},
zone: "example.com",
expectedError: transfer.ErrNotAuthoritative,
},
{
name: "TestSingleKubernetesTransferAuthZone",
kubernetes: []*mockK8sPlugin{
{
zones: []string{"cluster.local"},
transfer: `
cluster.local. 5 IN SOA ns.dns.cluster.local. hostmaster.cluster.local. 3 7200 1800 86400 5
cluster.local. 5 IN NS ns.dns.cluster.local.
ns.dns.cluster.local. 5 IN A 10.0.0.10
cluster.local. 5 IN SOA ns.dns.cluster.local. hostmaster.cluster.local. 3 7200 1800 86400 5
`,
transferErr: nil,
},
},
zone: "cluster.local",
expectedZone: `
cluster.local. 5 IN SOA ns.dns.cluster.local. hostmaster.cluster.local. 3 7200 1800 86400 5
cluster.local. 5 IN NS ns.dns.cluster.local.
ns.dns.cluster.local. 5 IN A 10.0.0.10
cluster.local. 5 IN SOA ns.dns.cluster.local. hostmaster.cluster.local. 3 7200 1800 86400 5
`,
expectedError: nil,
},
{
name: "TestMultipleNonAuthorititativeSingleAuthoritative",
kubernetes: []*mockK8sPlugin{
{
zones: []string{"fluster.local"},
transfer: `
fluster.local. 5 IN SOA ns.dns.fluster.local. hostmaster.fluster.local. 3 7200 1800 86400 5
fluster.local. 5 IN NS ns.dns.fluster.local.
ns.dns.fluster.local. 5 IN A 10.0.0.10
fluster.local. 5 IN SOA ns.dns.fluster.local. hostmaster.fluster.local. 3 7200 1800 86400 5
`,
transferErr: transfer.ErrNotAuthoritative,
},
{
zones: []string{"bluster.local"},
transferErr: transfer.ErrNotAuthoritative,
},
{
zones: []string{"cluster.local"},
transfer: `
cluster.local. 5 IN SOA ns.dns.cluster.local. hostmaster.cluster.local. 3 7200 1800 86400 5
cluster.local. 5 IN NS ns.dns.cluster.local.
ns.dns.cluster.local. 5 IN A 10.0.0.10
cluster.local. 5 IN SOA ns.dns.cluster.local. hostmaster.cluster.local. 3 7200 1800 86400 5
`,
transferErr: nil,
},
{
zones: []string{"muster.local"},
transferErr: transfer.ErrNotAuthoritative,
},
},
zone: "cluster.local",
expectedZone: `
cluster.local. 5 IN SOA ns.dns.cluster.local. hostmaster.cluster.local. 3 7200 1800 86400 5
cluster.local. 5 IN NS ns.dns.cluster.local.
ns.dns.cluster.local. 5 IN A 10.0.0.10
cluster.local. 5 IN SOA ns.dns.cluster.local. hostmaster.cluster.local. 3 7200 1800 86400 5
`,
expectedError: nil,
},
}

for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
// create kubernetai with mock kubernetes plugins
kai := Kubernetai{}
for _, plug := range tt.kubernetes {
kai.Kubernetes = append(kai.Kubernetes, plug)
}

// create a axfr test message with test zone
dnsmsg := &dns.Msg{}
dnsmsg.SetAxfr(tt.zone)

// perform AXFR
ch, err := kai.Transfer(tt.zone, tt.serial)
if err != nil {
if err != tt.expectedError {
t.Errorf("expected error %+v but received %+v", tt.expectedError, err)
}
return
}
validateAXFR(t, ch, tt.expectedZone)
})
}
}

func validateAXFR(t *testing.T, ch <-chan []dns.RR, expectedZone string) {
xfr := []dns.RR{}
for rrs := range ch {
xfr = append(xfr, rrs...)
}
if xfr[0].Header().Rrtype != dns.TypeSOA {
t.Error("Invalid transfer response, does not start with SOA record")
}

zp := dns.NewZoneParser(strings.NewReader(expectedZone), "", "")
i := 0
for rr, ok := zp.Next(); ok; rr, ok = zp.Next() {
if !dns.IsDuplicate(rr, xfr[i]) {
t.Fatalf("Record %d, expected\n%v\n, got\n%v", i, rr, xfr[i])
}
i++
}

if err := zp.Err(); err != nil {
t.Fatal(err)
}
}
73 changes: 65 additions & 8 deletions plugin/kubernetai/kubernetai.go
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Original file line number Diff line number Diff line change
@@ -1,33 +1,76 @@
// Package kubernetai implements a plugin which can embed a number of kubernetes plugins in the same dns server.
package kubernetai

import (
"context"

"github.com/coredns/coredns/plugin"
"github.com/coredns/coredns/plugin/kubernetes"
"github.com/coredns/coredns/plugin/kubernetes/object"
clog "github.com/coredns/coredns/plugin/pkg/log"
"github.com/coredns/coredns/plugin/transfer"
"github.com/coredns/coredns/request"
"github.com/miekg/dns"
)

var log = clog.NewWithPlugin("kubernetai")

// embeddedKubernetesPluginInterface describes the kubernetes plugin interface that kubernetai requires/uses.
type embeddedKubernetesPluginInterface interface {
plugin.Handler
transfer.Transferer
PodWithIP(ip string) (pod *object.Pod)
Zones() (zones plugin.Zones)
}

// embeddedKubernetes wraps a real kubernetes plugin
type embeddedKubernetes struct {
*kubernetes.Kubernetes
}

var _ embeddedKubernetesPluginInterface = &embeddedKubernetes{}

func newEmbeddedKubernetes(k *kubernetes.Kubernetes) *embeddedKubernetes {
return &embeddedKubernetes{
Kubernetes: k,
}
}

// PodWithIP satisfies the embeddedKubernetesPluginInterface by adding this additional method not exported from the kubernetes plugin.
func (ek embeddedKubernetes) PodWithIP(ip string) *object.Pod {
if ek.Kubernetes == nil {
return nil
}
ps := ek.Kubernetes.APIConn.PodIndex(ip)
if len(ps) == 0 {
return nil
}
return ps[0]
}

// Zones satisfies the embeddedKubernetesPluginInterface by providing access to the kubernetes plugin Zones.
func (ek embeddedKubernetes) Zones() plugin.Zones {
if ek.Kubernetes == nil {
return nil
}
return plugin.Zones(ek.Kubernetes.Zones)
}

// Kubernetai handles multiple Kubernetes
type Kubernetai struct {
Zones []string
Kubernetes []*kubernetes.Kubernetes
Kubernetes []embeddedKubernetesPluginInterface
autoPathSearch []string // Local search path from /etc/resolv.conf. Needed for autopath.
p podHandlerItf
}

// New creates a Kubernetai containing one Kubernetes with zones
func New(zones []string) (Kubernetai, *kubernetes.Kubernetes) {
h := Kubernetai{
autoPathSearch: searchFromResolvConf(),
p: &podHandler{},
}
k := kubernetes.New(zones)
h.Kubernetes = append(h.Kubernetes, k)
ek := newEmbeddedKubernetes(k)
h.Kubernetes = append(h.Kubernetes, ek)
return h, k
}

Expand All @@ -43,7 +86,7 @@ func (k8i Kubernetai) AutoPath(state request.Request) []string {
// Abort if zone is not in kubernetai stanza.
var zMatch bool
for _, k8s := range k8i.Kubernetes {
zone := plugin.Zones(k8s.Zones).Matches(state.Name())
zone := k8s.Zones().Matches(state.Name())
if zone != "" {
zMatch = true
break
Expand All @@ -55,13 +98,13 @@ func (k8i Kubernetai) AutoPath(state request.Request) []string {

// Add autopath result for the handled zones
for _, k := range k8i.Kubernetes {
pod := k8i.p.PodWithIP(*k, state.IP())
pod := k.PodWithIP(state.IP())
if pod == nil {
return nil
}

search := make([]string, 3)
for _, z := range k.Zones {
for _, z := range k.Zones() {
if z == "." {
search[0] = pod.Namespace + ".svc."
search[1] = "svc."
Expand All @@ -80,6 +123,20 @@ func (k8i Kubernetai) AutoPath(state request.Request) []string {
return searchPath
}

// Transfer supports the transfer plugin, implementing the Transferer interface, by calling Transfer on each of the embedded plugins.
// It will return a channel to the FIRST kubernetai stanza that reports that it is authoritative for the requested zone.
func (k8i Kubernetai) Transfer(zone string, serial uint32) (retCh <-chan []dns.RR, err error) {
for _, k := range k8i.Kubernetes {
retCh, err = k.Transfer(zone, serial)
if err == transfer.ErrNotAuthoritative {
continue
}
return
}
// none of the embedded plugins were authoritative
return nil, transfer.ErrNotAuthoritative
}

func searchFromResolvConf() []string {
rc, err := dns.ClientConfigFromFile("/etc/resolv.conf")
if err != nil {
Expand All @@ -93,7 +150,7 @@ func searchFromResolvConf() []string {
func (k8i Kubernetai) Health() bool {
healthy := true
for _, k := range k8i.Kubernetes {
healthy = healthy && k.APIConn.HasSynced()
healthy = healthy && k.(*embeddedKubernetes).APIConn.HasSynced()
if !healthy {
break
}
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