Merge pull request #943 from inercia/weave-941

make negative TTL default to same value as TTL

Fixes #941.

nameserver/cache.go

@@ -22,8 +22,6 @@ var (
 )
 
 const (
-	DefaultCacheNegLocalTTL = 30 // Default TTL for negative local resolutions
-
 	defPendingTimeout int = 5 // timeout for a resolution
 )
 

nameserver/cache_test.go

@@ -196,26 +196,26 @@ func TestCacheEntries(t *testing.T) {
 	question3 := &questionMsg3.Question[0]
 
 	t.Logf("Checking that a entry with CacheNoLocalReplies return an error")
-	l.Put(questionMsg3, nil, DefaultCacheNegLocalTTL, CacheNoLocalReplies)
+	l.Put(questionMsg3, nil, DefaultLocalTTL, CacheNoLocalReplies)
 	resp, err = l.Get(questionMsg3, minUDPSize)
 	wt.AssertNil(t, resp, "Get() response with CacheNoLocalReplies")
 	wt.AssertTrue(t, err == errNoLocalReplies, "Get() error with CacheNoLocalReplies")
 
 	t.Logf("Checking that more Put's do not make the negative TTL longer")
-	clk.Add(time.Duration(DefaultCacheNegLocalTTL/2) * time.Second)
-	l.Put(questionMsg3, nil, DefaultCacheNegLocalTTL, CacheNoLocalReplies)
+	clk.Add(time.Duration(DefaultLocalTTL/2) * time.Second)
+	l.Put(questionMsg3, nil, DefaultLocalTTL, CacheNoLocalReplies)
 	clk.Add(time.Duration(1) * time.Second)
-	l.Put(questionMsg3, nil, DefaultCacheNegLocalTTL, CacheNoLocalReplies)
+	l.Put(questionMsg3, nil, DefaultLocalTTL, CacheNoLocalReplies)
 	clk.Add(time.Duration(1) * time.Second)
-	l.Put(questionMsg3, nil, DefaultCacheNegLocalTTL, CacheNoLocalReplies)
+	l.Put(questionMsg3, nil, DefaultLocalTTL, CacheNoLocalReplies)
 	resp, err = l.Get(questionMsg3, minUDPSize)
 	wt.AssertNil(t, resp, "Get() response with CacheNoLocalReplies")
 	wt.AssertTrue(t, err == errNoLocalReplies, "Get() error with CacheNoLocalReplies")
 
-	clk.Add(time.Duration(DefaultCacheNegLocalTTL/2) * time.Second)
-	t.Logf("Checking that we get an expired response after %f seconds", DefaultCacheNegLocalTTL)
-	clk.Add(time.Second * time.Duration(DefaultCacheNegLocalTTL+1))
-	t.Logf("Checking that we get an expired response after %d seconds", DefaultCacheNegLocalTTL)
+	clk.Add(time.Duration(DefaultLocalTTL/2) * time.Second)
+	t.Logf("Checking that we get an expired response after %f seconds", DefaultLocalTTL)
+	clk.Add(time.Second * time.Duration(DefaultLocalTTL+1))
+	t.Logf("Checking that we get an expired response after %d seconds", DefaultLocalTTL)
 	resp, err = l.Get(questionMsg3, minUDPSize)
 	wt.AssertNil(t, resp, "expired Get() response with CacheNoLocalReplies")
 	wt.AssertNil(t, err, "expired Get() error with CacheNoLocalReplies")

nameserver/server.go

@@ -45,7 +45,7 @@ type DNSServerConfig struct {
 	Cache ZoneCache
 	// (Optional) TTL for local domain responses
 	LocalTTL int
-	// (Optional) TTL for negative results in the local domain
+	// (Optional) TTL for negative results in the local domain (defaults to LocalTTL)
 	CacheNegLocalTTL int
 	// (Optional) for a specific clock provider
 	Clock clock.Clock
@@ -120,7 +120,6 @@ func NewDNSServer(config DNSServerConfig) (s *DNSServer, err error) {
 		cacheDisabled: false,
 		maxAnswers:    DefaultMaxAnswers,
 		localTTL:      DefaultLocalTTL,
-		negLocalTTL:   DefaultCacheNegLocalTTL,
 		clock:         config.Clock,
 	}
 
@@ -164,6 +163,8 @@ func NewDNSServer(config DNSServerConfig) (s *DNSServer, err error) {
 	}
 	if config.CacheNegLocalTTL > 0 {
 		s.negLocalTTL = config.CacheNegLocalTTL
+	} else {
+		s.negLocalTTL = s.localTTL
 	}
 	if config.CacheDisabled {
 		s.cacheDisabled = true

prog/weavedns/main.go

@@ -5,13 +5,13 @@ import (
 	"fmt"
 	"net"
 	"os"
+	"strconv"
 
 	"github.com/miekg/dns"
 	. "github.com/weaveworks/weave/common"
 	"github.com/weaveworks/weave/common/docker"
 	weavedns "github.com/weaveworks/weave/nameserver"
 	weavenet "github.com/weaveworks/weave/net"
-	"strconv"
 )
 
 var version = "(unreleased version)"
@@ -55,7 +55,7 @@ func main() {
 	flag.BoolVar(&watch, "watch", true, "watch the docker socket for container events")
 	flag.BoolVar(&debug, "debug", false, "output debugging info to stderr")
 	// advanced options
-	flag.IntVar(&negTTL, "neg-ttl", weavedns.DefaultCacheNegLocalTTL, "negative TTL (in secs) for unanswered queries for local names")
+	flag.IntVar(&negTTL, "neg-ttl", 0, "negative TTL (in secs) for unanswered queries for local names")
 	flag.IntVar(&refreshInterval, "refresh", weavedns.DefaultRefreshInterval, "refresh interval (in secs) for local names (0=disable)")
 	flag.IntVar(&maxAnswers, "max-answers", weavedns.DefaultMaxAnswers, "maximum number of answers returned to clients (0=unlimited)")
 	flag.IntVar(&relevantTime, "relevant", weavedns.DefaultRelevantTime, "life time for info in the absence of queries (in secs)")