plugin/k8s_external: implement zone transfers (#4977)

Implement transfer for k8s_external. Notifies not supported.

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

plugin/k8s_external/transfer_test.go

@@ -0,0 +1,142 @@
+package external
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/coredns/coredns/plugin"
+	"github.com/coredns/coredns/plugin/kubernetes"
+	"github.com/coredns/coredns/plugin/test"
+	"github.com/coredns/coredns/plugin/transfer"
+
+	"github.com/miekg/dns"
+)
+
+func TestImplementsTransferer(t *testing.T) {
+	var e plugin.Handler
+	e = &External{}
+	_, ok := e.(transfer.Transferer)
+	if !ok {
+		t.Error("Transferer not implemented")
+	}
+}
+
+func TestTransferAXFR(t *testing.T) {
+	k := kubernetes.New([]string{"cluster.local."})
+	k.Namespaces = map[string]struct{}{"testns": {}}
+	k.APIConn = &external{}
+
+	e := New()
+	e.Zones = []string{"example.com."}
+	e.externalFunc = k.External
+	e.externalAddrFunc = externalAddress  // internal test function
+	e.externalSerialFunc = externalSerial // internal test function
+	e.externalServicesFunc = k.ExternalServices
+
+	ch, err := e.Transfer("example.com.", 0)
+
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	var records []dns.RR
+	for rrs := range ch {
+		records = append(records, rrs...)
+	}
+
+	expect := []dns.RR{}
+	for _, tc := range append(tests, testsApex...) {
+		if tc.Rcode != dns.RcodeSuccess {
+			continue
+		}
+
+		for _, ans := range tc.Answer {
+			// Exclude wildcard test cases
+			if strings.Contains(ans.Header().Name, "*") {
+				continue
+			}
+
+			// Exclude TXT records
+			if ans.Header().Rrtype == dns.TypeTXT {
+				continue
+			}
+			expect = append(expect, ans)
+		}
+	}
+
+	diff := difference(expect, records)
+	if len(diff) != 0 {
+		t.Errorf("Got back %d records that do not exist in test cases, should be 0:", len(diff))
+		for _, rec := range diff {
+			t.Errorf("%+v", rec)
+		}
+	}
+
+	diff = difference(records, expect)
+	if len(diff) != 0 {
+		t.Errorf("Result is missing %d records, should be 0:", len(diff))
+		for _, rec := range diff {
+			t.Errorf("%+v", rec)
+		}
+	}
+
+}
+
+func TestTransferIXFR(t *testing.T) {
+	k := kubernetes.New([]string{"cluster.local."})
+	k.Namespaces = map[string]struct{}{"testns": {}}
+	k.APIConn = &external{}
+
+	e := New()
+	e.Zones = []string{"example.com."}
+	e.externalFunc = k.External
+	e.externalAddrFunc = externalAddress  // internal test function
+	e.externalSerialFunc = externalSerial // internal test function
+	e.externalServicesFunc = k.ExternalServices
+
+	ch, err := e.Transfer("example.com.", externalSerial("example.com."))
+
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	var records []dns.RR
+	for rrs := range ch {
+		records = append(records, rrs...)
+	}
+
+	expect := []dns.RR{
+		test.SOA("example.com.	5	IN	SOA	ns1.dns.example.com. hostmaster.dns.example.com. 1499347823 7200 1800 86400 5"),
+	}
+
+	diff := difference(expect, records)
+	if len(diff) != 0 {
+		t.Errorf("Got back %d records that do not exist in test cases, should be 0:", len(diff))
+		for _, rec := range diff {
+			t.Errorf("%+v", rec)
+		}
+	}
+
+	diff = difference(records, expect)
+	if len(diff) != 0 {
+		t.Errorf("Result is missing %d records, should be 0:", len(diff))
+		for _, rec := range diff {
+			t.Errorf("%+v", rec)
+		}
+	}
+
+}
+
+// difference shows what we're missing when comparing two RR slices
+func difference(testRRs []dns.RR, gotRRs []dns.RR) []dns.RR {
+	expectedRRs := map[string]struct{}{}
+	for _, rr := range testRRs {
+		expectedRRs[rr.String()] = struct{}{}
+	}
+
+	foundRRs := []dns.RR{}
+	for _, rr := range gotRRs {
+		if _, ok := expectedRRs[rr.String()]; !ok {
+			foundRRs = append(foundRRs, rr)
+		}
+	}
+	return foundRRs
+}