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ServiceBackend interface (#369)

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* Add ServiceBackend interface

This adds a ServiceBackend interface that is shared between etcd/etcd3
(later) and kubernetes, leading to a massive reduction in code. When
returning the specific records from their backend.

Fixes #273
This commit is contained in:
Miek Gieben 2016-10-30 15:54:16 +00:00 • committed by GitHub
parent 81d5baee28
commit 27d893cf33
15 changed files with 273 additions and 503 deletions
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39
middleware/kubernetes/handler.go
View file

@ -23,6 +23,8 @@ func (k Kubernetes) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.M
m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
// TODO: find an alternative to this block
// TODO(miek): Why is this even here, why does the path Etcd takes not work?
// Should be a "case PTR" below. I would also like to use middleware.PTR for this.
ip := dnsutil.ExtractAddressFromReverse(state.Name())
if ip != "" {
records := k.getServiceRecordForIP(ip, state.Name())
@ -54,41 +56,38 @@ func (k Kubernetes) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.M
)
switch state.Type() {
case "A":
records, err = k.A(zone, state, nil)
records, _, err = middleware.A(&k, zone, state, nil, middleware.Options{}) // Hmm wrt to '&k'
case "AAAA":
records, err = k.AAAA(zone, state, nil)
records, _, err = middleware.AAAA(&k, zone, state, nil, middleware.Options{})
case "TXT":
records, err = k.TXT(zone, state)
// TODO: change lookup to return appropriate error. Then add code below
// this switch to check for the error and return not implemented.
//return dns.RcodeNotImplemented, nil
records, _, err = middleware.TXT(&k, zone, state, middleware.Options{})
case "CNAME":
records, err = k.CNAME(zone, state)
records, _, err = middleware.CNAME(&k, zone, state, middleware.Options{})
case "MX":
records, extra, err = k.MX(zone, state)
records, extra, _, err = middleware.MX(&k, zone, state, middleware.Options{})
case "SRV":
records, extra, err = k.SRV(zone, state)
records, extra, _, err = middleware.SRV(&k, zone, state, middleware.Options{})
case "SOA":
records = []dns.RR{k.SOA(zone, state)}
records, _, err = middleware.SOA(&k, zone, state, middleware.Options{})
case "NS":
if state.Name() == zone {
records, extra, err = k.NS(zone, state)
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 = k.A(zone, state, nil)
_, _, err = middleware.A(&k, zone, state, nil, middleware.Options{})
}
if isKubernetesNameError(err) {
return k.Err(zone, dns.RcodeNameError, state)
if k.IsNameError(err) {
return middleware.BackendError(&k, zone, dns.RcodeNameError, state, nil /*debug*/, err, middleware.Options{})
}
if err != nil {
return dns.RcodeServerFailure, err
}
if len(records) == 0 {
return k.Err(zone, dns.RcodeSuccess, state)
return middleware.BackendError(&k, zone, dns.RcodeSuccess, state, nil /*debug*/, nil, middleware.Options{})
}
m.Answer = append(m.Answer, records...)
@ -103,13 +102,3 @@ func (k Kubernetes) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.M
// Name implements the Handler interface.
func (k Kubernetes) Name() string { return "kubernetes" }
// Err writes an error response back to the client.
func (k Kubernetes) Err(zone string, rcode int, state request.Request) (int, error) {
m := new(dns.Msg)
m.SetRcode(state.Req, rcode)
m.Ns = []dns.RR{k.SOA(zone, state)}
state.SizeAndDo(m)
state.W.WriteMsg(m)
return rcode, nil
}