d04abdf422
* Laying down kubernetes middleware foundation * Duplicated a bunch of code form etcd middleware * Duplicated code hacked to compile and load as a separate middleware * Adding verbose build option to Makefile * Removing stubzone and tls support tls and stubzone support was carried over from base etcd middleware code. Removing to simplify the kube middleware implementation. (For now.) * Adding conf directory for sample conf files * Removing stubzone support from query handler * Remove upstream and proxy from k8s corefile. Not sure that upstream or proxy makes sense for a k8s backed zone. * Comment out use of singleflight serialization * Removing parsing support for "upstream" directive from k8s * Removing upstream directive parsing code * Removing CNAME and TXT lookup implementation * Create README.md Brain-dump of DNS record name assembly and open work items. * Adding notes about wildcard handling * Adding basic k8s API client * Fleshing out methods on k8s connector * Remove PathPrefix from middleware init * Removing incorrect plural * Adding brute-force k8s service lookup functions * Initializing k8s API connector during startup * Hacking around to call k8s connector * Parsing incoming domain name into serviceName and namespace * Improving and simplifying k8s zone matching and label segmentation * Removing unused functions carried over from etcd middleware * Adding basic return of k8s data to DNS client * updated debugging println statements to flag with "[debug]" * removed code in kubernetes.go::Records that was a hold-over from etcd middleware. * Removed some random exploratory hacking. * Minior README.md updates * Updating with demo instructions * Updating README.md with CoreFile and removing completed TODO items * Updating conf file and README to reflect DNS response cache works * Disabling DNS response caching * Adding debug statement on entry to Records() * Changing port number in exampes to port 53. * Misc style and clarity changes * Removing empty function definitions * Adding comment to track future cleanup * Refactoring README to follow style of other middleware * Exposing dataobject field (typo)
101 lines
2.4 KiB
Go
101 lines
2.4 KiB
Go
package kubernetes
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import (
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"fmt"
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"github.com/miekg/coredns/middleware"
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"github.com/miekg/dns"
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"golang.org/x/net/context"
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)
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func (k Kubernetes) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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fmt.Println("[debug] here entering ServeDNS: ctx:%v dnsmsg:%v", ctx, r)
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state := middleware.State{W: w, Req: r}
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if state.QClass() != dns.ClassINET {
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return dns.RcodeServerFailure, fmt.Errorf("can only deal with ClassINET")
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}
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// Check that query matches one of the zones served by this middleware,
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// otherwise delegate to the next in the pipeline.
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zone := middleware.Zones(k.Zones).Matches(state.Name())
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if zone == "" {
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if k.Next == nil {
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return dns.RcodeServerFailure, nil
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}
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return k.Next.ServeDNS(ctx, w, r)
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}
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m := new(dns.Msg)
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m.SetReply(r)
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m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
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var (
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records, extra []dns.RR
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err error
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)
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switch state.Type() {
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case "A":
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records, err = k.A(zone, state, nil)
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case "AAAA":
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records, err = k.AAAA(zone, state, nil)
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case "TXT":
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records, err = k.TXT(zone, state)
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case "CNAME":
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records, err = k.CNAME(zone, state)
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case "MX":
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records, extra, err = k.MX(zone, state)
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case "SRV":
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records, extra, err = k.SRV(zone, state)
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case "SOA":
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records = []dns.RR{k.SOA(zone, state)}
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case "NS":
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if state.Name() == zone {
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records, extra, err = k.NS(zone, state)
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break
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}
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fallthrough
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default:
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// Do a fake A lookup, so we can distinguish betwen NODATA and NXDOMAIN
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_, err = k.A(zone, state, nil)
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}
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if isKubernetesNameError(err) {
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return k.Err(zone, dns.RcodeNameError, state)
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}
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if err != nil {
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return dns.RcodeServerFailure, err
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}
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if len(records) == 0 {
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return k.Err(zone, dns.RcodeSuccess, state)
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}
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m.Answer = append(m.Answer, records...)
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m.Extra = append(m.Extra, extra...)
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m = dedup(m)
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state.SizeAndDo(m)
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m, _ = state.Scrub(m)
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w.WriteMsg(m)
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return dns.RcodeSuccess, nil
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}
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// NoData write a nodata response to the client.
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func (k Kubernetes) Err(zone string, rcode int, state middleware.State) (int, error) {
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m := new(dns.Msg)
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m.SetRcode(state.Req, rcode)
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m.Ns = []dns.RR{k.SOA(zone, state)}
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state.SizeAndDo(m)
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state.W.WriteMsg(m)
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return rcode, nil
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}
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func dedup(m *dns.Msg) *dns.Msg {
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// TODO(miek): expensive!
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m.Answer = dns.Dedup(m.Answer, nil)
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m.Ns = dns.Dedup(m.Ns, nil)
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m.Extra = dns.Dedup(m.Extra, nil)
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return m
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}
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