aboutsummaryrefslogtreecommitdiff
path: root/middleware/loadbalance
diff options
context:
space:
mode:
Diffstat (limited to 'middleware/loadbalance')
-rw-r--r--middleware/loadbalance/loadbalance.go23
-rw-r--r--middleware/loadbalance/loadbalance.md4
-rw-r--r--middleware/loadbalance/loadbalance_test.go104
3 files changed, 120 insertions, 11 deletions
diff --git a/middleware/loadbalance/loadbalance.go b/middleware/loadbalance/loadbalance.go
index c81ad0c8a..e1bee25fd 100644
--- a/middleware/loadbalance/loadbalance.go
+++ b/middleware/loadbalance/loadbalance.go
@@ -14,18 +14,21 @@ func (r *RoundRobinResponseWriter) WriteMsg(res *dns.Msg) error {
if res.Rcode != dns.RcodeSuccess {
return r.ResponseWriter.WriteMsg(res)
}
- if len(res.Answer) < 2 { // don't even bother
- return r.ResponseWriter.WriteMsg(res)
- }
- // put CNAMEs first, randomize a/aaaa's and put packet back together.
- // TODO(miek): check family and give v6 more prio?
+ res.Answer = roundRobin(res.Answer)
+ res.Extra = roundRobin(res.Extra)
+
+ return r.ResponseWriter.WriteMsg(res)
+}
+
+func roundRobin(in []dns.RR) []dns.RR {
cname := []dns.RR{}
address := []dns.RR{}
rest := []dns.RR{}
- for _, r := range res.Answer {
+ for _, r := range in {
switch r.Header().Rrtype {
case dns.TypeCNAME:
+ // d d d d DNAME and friends here as well?
cname = append(cname, r)
case dns.TypeA, dns.TypeAAAA:
address = append(address, r)
@@ -36,7 +39,7 @@ func (r *RoundRobinResponseWriter) WriteMsg(res *dns.Msg) error {
switch l := len(address); l {
case 0, 1:
- return r.ResponseWriter.WriteMsg(res)
+ break
case 2:
if dns.Id()%2 == 0 {
address[0], address[1] = address[1], address[0]
@@ -51,9 +54,9 @@ func (r *RoundRobinResponseWriter) WriteMsg(res *dns.Msg) error {
address[q], address[p] = address[p], address[q]
}
}
- res.Answer = append(cname, rest...)
- res.Answer = append(res.Answer, address...)
- return r.ResponseWriter.WriteMsg(res)
+ out := append(cname, rest...)
+ out = append(out, address...)
+ return out
}
// Should we pack and unpack here to fiddle with the packet... Not likely.
diff --git a/middleware/loadbalance/loadbalance.md b/middleware/loadbalance/loadbalance.md
index 0e931fb53..5c381135d 100644
--- a/middleware/loadbalance/loadbalance.md
+++ b/middleware/loadbalance/loadbalance.md
@@ -4,13 +4,15 @@
message. See [Wikipedia](https://en.wikipedia.org/wiki/Round-robin_DNS) about the pros and cons
on this setup.
+It will take care to sort any CNAMEs before any address records.
+
## Syntax
~~~
loadbalance [policy]
~~~
-* policy is how to balance, the default is "round_robin"
+* `policy` is how to balance, the default is "round_robin"
## Examples
diff --git a/middleware/loadbalance/loadbalance_test.go b/middleware/loadbalance/loadbalance_test.go
new file mode 100644
index 000000000..dc027607c
--- /dev/null
+++ b/middleware/loadbalance/loadbalance_test.go
@@ -0,0 +1,104 @@
+package loadbalance
+
+import (
+ "testing"
+
+ "github.com/miekg/coredns/middleware"
+
+ "github.com/miekg/dns"
+ "golang.org/x/net/context"
+)
+
+func TestLoadBalance(t *testing.T) {
+ rm := RoundRobin{Next: handler()}
+
+ // the first X records must be cnames after this test
+ tests := []struct {
+ answer []dns.RR
+ extra []dns.RR
+ cnameAnswer int
+ cnameExtra int
+ }{
+ {
+ answer: []dns.RR{
+ newCNAME("cname1.region2.skydns.test. 300 IN CNAME cname2.region2.skydns.test."),
+ newCNAME("cname2.region2.skydns.test. 300 IN CNAME cname3.region2.skydns.test."),
+ newCNAME("cname5.region2.skydns.test. 300 IN CNAME cname6.region2.skydns.test."),
+ newCNAME("cname6.region2.skydns.test. 300 IN CNAME endpoint.region2.skydns.test."),
+ newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.1"),
+ },
+ cnameAnswer: 4,
+ },
+ {
+ answer: []dns.RR{
+ newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.1"),
+ newCNAME("cname.region2.skydns.test. 300 IN CNAME endpoint.region2.skydns.test."),
+ },
+ cnameAnswer: 1,
+ },
+ {
+ answer: []dns.RR{
+ newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.1"),
+ newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.2"),
+ newCNAME("cname2.region2.skydns.test. 300 IN CNAME cname3.region2.skydns.test."),
+ newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.3"),
+ },
+ extra: []dns.RR{
+ newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.1"),
+ newAAAA("endpoint.region2.skydns.test. 300 IN AAAA ::1"),
+ newCNAME("cname2.region2.skydns.test. 300 IN CNAME cname3.region2.skydns.test."),
+ newA("endpoint.region2.skydns.test. 300 IN A 10.240.0.3"),
+ newAAAA("endpoint.region2.skydns.test. 300 IN AAAA ::2"),
+ },
+ cnameAnswer: 1,
+ cnameExtra: 1,
+ },
+ }
+
+ rec := middleware.NewResponseRecorder(&middleware.TestResponseWriter{})
+
+ for i, test := range tests {
+ req := new(dns.Msg)
+ req.SetQuestion("region2.skydns.test.", dns.TypeSRV)
+ req.Answer = test.answer
+ req.Extra = test.extra
+
+ _, err := rm.ServeDNS(context.TODO(), rec, req)
+ if err != nil {
+ t.Errorf("Test %d: Expected no error, but got %s", i, err)
+ continue
+
+ }
+ cname := 0
+ for _, r := range rec.Msg().Answer {
+ if r.Header().Rrtype != dns.TypeCNAME {
+ break
+ }
+ cname++
+ }
+ if cname != test.cnameAnswer {
+ t.Errorf("Test %d: Expected %d cnames in Answer, but got %d", i, test.cnameAnswer, cname)
+ }
+ cname = 0
+ for _, r := range rec.Msg().Extra {
+ if r.Header().Rrtype != dns.TypeCNAME {
+ break
+ }
+ cname++
+ }
+ if cname != test.cnameExtra {
+ t.Errorf("Test %d: Expected %d cname in Extra, but got %d", i, test.cnameExtra, cname)
+ }
+ }
+}
+
+func handler() middleware.Handler {
+ return middleware.HandlerFunc(func(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
+ w.WriteMsg(r)
+ return dns.RcodeSuccess, nil
+ })
+}
+
+func newA(rr string) *dns.A { r, _ := dns.NewRR(rr); return r.(*dns.A) }
+func newAAAA(rr string) *dns.AAAA { r, _ := dns.NewRR(rr); return r.(*dns.AAAA) }
+func newCNAME(rr string) *dns.CNAME { r, _ := dns.NewRR(rr); return r.(*dns.CNAME) }
generated by cgit v1.2.3 (git 2.46.0) at 2025-08-17 14:00:17 +0000