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ADD ignoreemptyservice option for kubernetes plugin (#1813)

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* ADD: ignoreemptyservice option for kubernetes plugin

* Modify documentation and rename option to add space

* UPD: Add unit tests

* UPD: gofmt

* Add unit test for ignore emptyservice

* gofmt

* xfr tests failed

* Rename emptyservice to empty_service
This commit is contained in:
darkweaver87 2018-05-23 14:57:59 +02:00 • committed by Chris O'Haver
parent 0f74281a53
commit 003e104fca
7 changed files with 218 additions and 3 deletions
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3
plugin/kubernetes/README.md
View file

@ -101,6 +101,9 @@ kubernetes [ZONES...] {
the query. If **[ZONES...]** is omitted, then fallthrough happens for all zones for which the plugin
is authoritative. If specific zones are listed (for example `in-addr.arpa` and `ip6.arpa`), then only
queries for those zones will be subject to fallthrough.
* `ignore empty_service` return NXDOMAIN for services without any ready endpoint addresses (e.g. ready pods).
This allows the querying pod to continue searching for the service in the search path.
The search path could, for example, include another kubernetes cluster.
## Health

1
plugin/kubernetes/controller.go
View file

@ -79,6 +79,7 @@ type dnsControlOpts struct {
initPodCache bool
initEndpointsCache bool
resyncPeriod time.Duration
ignoreEmptyService bool
// Label handling.
labelSelector *meta.LabelSelector
selector labels.Selector

55
plugin/kubernetes/handler_ignore_emptyservice_test.go Normal file
View file

@ -0,0 +1,55 @@
package kubernetes
import (
"context"
"github.com/coredns/coredns/plugin/pkg/dnstest"
"github.com/coredns/coredns/plugin/test"
"testing"
"github.com/miekg/dns"
)
var dnsEmptyServiceTestCases = []test.Case{
// A Service
{
Qname: "svcempty.testns.svc.cluster.local.", Qtype: dns.TypeA,
Rcode: dns.RcodeNameError,
Ns: []dns.RR{
test.SOA("cluster.local. 300 IN SOA ns.dns.cluster.local. hostmaster.cluster.local. 1499347823 7200 1800 86400 60"),
},
},
}
func TestServeDNSEmptyService(t *testing.T) {
k := New([]string{"cluster.local."})
k.APIConn = &APIConnServeTest{}
k.opts.ignoreEmptyService = true
k.Next = test.NextHandler(dns.RcodeSuccess, nil)
ctx := context.TODO()
for i, tc := range dnsEmptyServiceTestCases {
r := tc.Msg()
w := dnstest.NewRecorder(&test.ResponseWriter{})
_, err := k.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)
}
// Before sorting, make sure that CNAMES do not appear after their target records
test.CNAMEOrder(t, resp)
test.SortAndCheck(t, resp, tc)
}
}

62
plugin/kubernetes/handler_test.go
View file

@ -22,6 +22,13 @@ var dnsTestCases = []test.Case{
test.A("svc1.testns.svc.cluster.local. 5 IN A 10.0.0.1"),
},
},
{
Qname: "svcempty.testns.svc.cluster.local.", Qtype: dns.TypeA,
Rcode: dns.RcodeSuccess,
Answer: []dns.RR{
test.A("svcempty.testns.svc.cluster.local. 5 IN A 10.0.0.1"),
},
},
// A Service (wildcard)
{
Qname: "svc1.*.svc.cluster.local.", Qtype: dns.TypeA,
@ -36,6 +43,12 @@ var dnsTestCases = []test.Case{
Answer: []dns.RR{test.SRV("svc1.testns.svc.cluster.local. 5 IN SRV 0 100 80 svc1.testns.svc.cluster.local.")},
Extra: []dns.RR{test.A("svc1.testns.svc.cluster.local. 5 IN A 10.0.0.1")},
},
{
Qname: "svcempty.testns.svc.cluster.local.", Qtype: dns.TypeSRV,
Rcode: dns.RcodeSuccess,
Answer: []dns.RR{test.SRV("svcempty.testns.svc.cluster.local. 5 IN SRV 0 100 80 svcempty.testns.svc.cluster.local.")},
Extra: []dns.RR{test.A("svcempty.testns.svc.cluster.local. 5 IN A 10.0.0.1")},
},
{
Qname: "svc6.testns.svc.cluster.local.", Qtype: dns.TypeSRV,
Rcode: dns.RcodeSuccess,
@ -49,6 +62,12 @@ var dnsTestCases = []test.Case{
Answer: []dns.RR{test.SRV("svc1.*.svc.cluster.local. 5 IN SRV 0 100 80 svc1.testns.svc.cluster.local.")},
Extra: []dns.RR{test.A("svc1.testns.svc.cluster.local. 5 IN A 10.0.0.1")},
},
{
Qname: "svcempty.*.svc.cluster.local.", Qtype: dns.TypeSRV,
Rcode: dns.RcodeSuccess,
Answer: []dns.RR{test.SRV("svcempty.*.svc.cluster.local. 5 IN SRV 0 100 80 svcempty.testns.svc.cluster.local.")},
Extra: []dns.RR{test.A("svcempty.testns.svc.cluster.local. 5 IN A 10.0.0.1")},
},
// SRV Service (wildcards)
{
Qname: "*.any.svc1.*.svc.cluster.local.", Qtype: dns.TypeSRV,
@ -83,6 +102,16 @@ var dnsTestCases = []test.Case{
test.A("svc1.testns.svc.cluster.local. 5 IN A 10.0.0.1"),
},
},
{
Qname: "_http._tcp.svcempty.testns.svc.cluster.local.", Qtype: dns.TypeSRV,
Rcode: dns.RcodeSuccess,
Answer: []dns.RR{
test.SRV("_http._tcp.svcempty.testns.svc.cluster.local. 5 IN SRV 0 100 80 svcempty.testns.svc.cluster.local."),
},
Extra: []dns.RR{
test.A("svcempty.testns.svc.cluster.local. 5 IN A 10.0.0.1"),
},
},
// A Service (Headless)
{
Qname: "hdls1.testns.svc.cluster.local.", Qtype: dns.TypeA,
@ -332,6 +361,21 @@ var svcIndex = map[string][]*api.Service{
}},
},
}},
"svcempty.testns": {{
ObjectMeta: meta.ObjectMeta{
Name: "svcempty",
Namespace: "testns",
},
Spec: api.ServiceSpec{
Type: api.ServiceTypeClusterIP,
ClusterIP: "10.0.0.1",
Ports: []api.ServicePort{{
Name: "http",
Protocol: "tcp",
Port: 80,
}},
},
}},
"svc6.testns": {{
ObjectMeta: meta.ObjectMeta{
Name: "svc6",
@ -410,6 +454,24 @@ var epsIndex = map[string][]*api.Endpoints{
Namespace: "testns",
},
}},
"svcempty.testns": {{
Subsets: []api.EndpointSubset{
{
Addresses: nil,
Ports: []api.EndpointPort{
{
Port: 80,
Protocol: "tcp",
Name: "http",
},
},
},
},
ObjectMeta: meta.ObjectMeta{
Name: "svcempty",
Namespace: "testns",
},
}},
"hdls1.testns": {{
Subsets: []api.EndpointSubset{
{

17
plugin/kubernetes/kubernetes.go
View file

@ -89,7 +89,6 @@ var (
// Services implements the ServiceBackend interface.
func (k *Kubernetes) Services(state request.Request, exact bool, opt plugin.Options) (svcs []msg.Service, err error) {
// We're looking again at types, which we've already done in ServeDNS, but there are some types k8s just can't answer.
switch state.QType() {
@ -240,7 +239,6 @@ func (k *Kubernetes) getClientConfig() (*rest.Config, error) {
// InitKubeCache initializes a new Kubernetes cache.
func (k *Kubernetes) InitKubeCache() (err error) {
config, err := k.getClientConfig()
if err != nil {
return err
@ -398,7 +396,6 @@ func (k *Kubernetes) findServices(r recordRequest, zone string) (services []msg.
}
for _, svc := range serviceList {
if !(match(r.namespace, svc.Namespace) && match(r.service, svc.Name)) {
continue
}
@ -409,6 +406,20 @@ func (k *Kubernetes) findServices(r recordRequest, zone string) (services []msg.
continue
}
if k.opts.ignoreEmptyService && svc.Spec.ClusterIP != api.ClusterIPNone {
// serve NXDOMAIN if no endpoint is able to answer
podsCount := 0
for _, ep := range endpointsListFunc() {
for _, eps := range ep.Subsets {
podsCount = podsCount + len(eps.Addresses)
}
}
if podsCount == 0 {
continue
}
}
// Endpoint query or headless service
if svc.Spec.ClusterIP == api.ClusterIPNone || r.endpoint != "" {
if endpointsList == nil {

13
plugin/kubernetes/setup.go
View file

@ -115,6 +115,7 @@ func ParseStanza(c *caddy.Controller) (*Kubernetes, error) {
opts := dnsControlOpts{
initEndpointsCache: true,
ignoreEmptyService: false,
resyncPeriod: defaultResyncPeriod,
}
k8s.opts = opts
@ -249,10 +250,22 @@ func ParseStanza(c *caddy.Controller) (*Kubernetes, error) {
return nil, c.ArgErr()
}
k8s.opts.initEndpointsCache = false
case "ignore":
args := c.RemainingArgs()
if len(args) > 0 {
ignore := args[0]
if ignore == "empty_service" {
k8s.opts.ignoreEmptyService = true
continue
} else {
return nil, fmt.Errorf("unable to parse ignore value: '%v'", ignore)
}
}
default:
return nil, c.Errf("unknown property '%s'", c.Val())
}
}
return k8s, nil
}

70
plugin/kubernetes/setup_test.go
View file

@ -615,3 +615,73 @@ func TestKubernetesParseNoEndpoints(t *testing.T) {
}
}
}
func TestKubernetesParseIgnoreEmptyService(t *testing.T) {
tests := []struct {
input string // Corefile data as string
shouldErr bool // true if test case is exected to produce an error.
expectedErrContent string // substring from the expected error. Empty for positive cases.
expectedEndpointsInit bool
}{
// valid
{
`kubernetes coredns.local {
ignore empty_service
}`,
false,
"",
true,
},
// invalid
{
`kubernetes coredns.local {
ignore ixnay on the endpointsay
}`,
true,
"unable to parse ignore value",
false,
},
{
`kubernetes coredns.local {
ignore empty_service ixnay on the endpointsay
}`,
false,
"",
true,
},
// not set
{
`kubernetes coredns.local {
}`,
false,
"",
false,
},
}
for i, test := range tests {
c := caddy.NewTestController("dns", test.input)
k8sController, err := kubernetesParse(c)
if test.shouldErr && err == nil {
t.Errorf("Test %d: Expected error, but did not find error for input '%s'. Error was: '%v'", i, test.input, err)
}
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)
continue
}
if !strings.Contains(err.Error(), test.expectedErrContent) {
t.Errorf("Test %d: Expected error to contain: %v, found error: %v, input: %s", i, test.expectedErrContent, err, test.input)
}
continue
}
foundIgnoreEmptyService := k8sController.opts.ignoreEmptyService
if foundIgnoreEmptyService != test.expectedEndpointsInit {
t.Errorf("Test %d: Expected kubernetes controller to be initialized with ignore empty_service '%v'. Instead found ignore empty_service watch '%v' for input '%s'", i, test.expectedEndpointsInit, foundIgnoreEmptyService, test.input)
}
}
}