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middleware/kubernetes: Server side path lookups (#750)

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* initial commit

* add config options

* add readme

* rewording

* revert unlreated change

* normalize host domain path

* add ndots opt, allow > 1 host domains, pull host domains from resolv.conf

* implementing review feedback

* update readme

* use dns lib, config format, defaults

* Correct autopath example.
This commit is contained in:
Chris O'Haver 2017-06-28 18:44:30 -04:00 • committed by John Belamaric
parent 817f3960b8
commit edf71fb168
6 changed files with 407 additions and 51 deletions
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109
middleware/kubernetes/handler.go
View file

@ -2,9 +2,11 @@ package kubernetes
import (
"errors"
"strings"
"github.com/coredns/coredns/middleware"
"github.com/coredns/coredns/middleware/pkg/dnsutil"
"github.com/coredns/coredns/middleware/rewrite"
"github.com/coredns/coredns/request"
"github.com/miekg/dns"
@ -39,37 +41,55 @@ func (k Kubernetes) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.M
zone = state.Name()
}
var (
records, extra []dns.RR
err error
)
switch state.Type() {
case "A":
records, _, err = middleware.A(&k, zone, state, nil, middleware.Options{})
case "AAAA":
records, _, err = middleware.AAAA(&k, zone, state, nil, middleware.Options{})
case "TXT":
records, _, err = middleware.TXT(&k, zone, state, middleware.Options{})
case "CNAME":
records, _, err = middleware.CNAME(&k, zone, state, middleware.Options{})
case "PTR":
records, _, err = middleware.PTR(&k, zone, state, middleware.Options{})
case "MX":
records, extra, _, err = middleware.MX(&k, zone, state, middleware.Options{})
case "SRV":
records, extra, _, err = middleware.SRV(&k, zone, state, middleware.Options{})
case "SOA":
records, _, err = middleware.SOA(&k, zone, state, middleware.Options{})
case "NS":
if state.Name() == zone {
records, extra, _, err = middleware.NS(&k, zone, state, middleware.Options{})
break
records, extra, _, err := k.routeRequest(zone, state)
if k.AutoPath.Enabled && k.IsNameError(err) {
p := k.findPodWithIP(state.IP())
for p != nil {
name, path, ok := splitSearch(zone, state.QName(), p.Namespace)
if !ok {
break
}
if (dns.CountLabel(name) - 1) < k.AutoPath.NDots {
break
}
// Search "svc.cluster.local" and "cluster.local"
for i := 0; i < 2; i++ {
path = strings.Join(dns.SplitDomainName(path)[1:], ".")
state = state.NewWithQuestion(strings.Join([]string{name, path}, "."), state.QType())
records, extra, _, err = k.routeRequest(zone, state)
if !k.IsNameError(err) {
break
}
}
if !k.IsNameError(err) {
break
}
// Fallthrough with the host search path (if set)
wr := rewrite.NewResponseReverter(w, r)
for _, hostsearch := range k.AutoPath.HostSearchPath {
r = state.NewWithQuestion(strings.Join([]string{name, hostsearch}, "."), state.QType()).Req
rcode, nextErr := middleware.NextOrFailure(k.Name(), k.Next, ctx, wr, r)
if rcode == dns.RcodeSuccess {
return rcode, nextErr
}
}
// Search . in this middleware
state = state.NewWithQuestion(strings.Join([]string{name, "."}, ""), state.QType())
records, extra, _, err = k.routeRequest(zone, state)
if !k.IsNameError(err) {
break
}
// Search . in the next middleware
r = state.Req
rcode, nextErr := middleware.NextOrFailure(k.Name(), k.Next, ctx, wr, r)
if rcode == dns.RcodeNameError {
rcode = k.AutoPath.OnNXDOMAIN
}
return rcode, nextErr
}
fallthrough
default:
// Do a fake A lookup, so we can distinguish between NODATA and NXDOMAIN
_, _, err = middleware.A(&k, zone, state, nil, middleware.Options{})
}
if k.IsNameError(err) {
if k.Fallthrough {
return middleware.NextOrFailure(k.Name(), k.Next, ctx, w, r)
@ -95,5 +115,36 @@ func (k Kubernetes) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.M
return dns.RcodeSuccess, nil
}
func (k *Kubernetes) routeRequest(zone string, state request.Request) (records []dns.RR, extra []dns.RR, debug []dns.RR, err error) {
switch state.Type() {
case "A":
records, _, err = middleware.A(k, zone, state, nil, middleware.Options{})
case "AAAA":
records, _, err = middleware.AAAA(k, zone, state, nil, middleware.Options{})
case "TXT":
records, _, err = middleware.TXT(k, zone, state, middleware.Options{})
case "CNAME":
records, _, err = middleware.CNAME(k, zone, state, middleware.Options{})
case "PTR":
records, _, err = middleware.PTR(k, zone, state, middleware.Options{})
case "MX":
records, extra, _, err = middleware.MX(k, zone, state, middleware.Options{})
case "SRV":
records, extra, _, err = middleware.SRV(k, zone, state, middleware.Options{})
case "SOA":
records, _, err = middleware.SOA(k, zone, state, middleware.Options{})
case "NS":
if state.Name() == zone {
records, extra, _, err = middleware.NS(k, zone, state, middleware.Options{})
break
}
fallthrough
default:
// Do a fake A lookup, so we can distinguish between NODATA and NXDOMAIN
_, _, err = middleware.A(k, zone, state, nil, middleware.Options{})
}
return records, extra, nil, err
}
// Name implements the Handler interface.
func (k Kubernetes) Name() string { return "kubernetes" }