add ttl as param to ip cache

pkg/master/ip_cache.go

@@ -36,16 +36,21 @@ type ipCache struct {
 	cloudProvider cloudprovider.Interface
 	cache         map[string]ipCacheEntry
 	lock          sync.Mutex
+	ttl           time.Duration
 }
 
 // NewIPCache makes a new ip caching layer, which will get IP addresses from cp,
 // and use clock for deciding when to re-get an IP address.
 // Thread-safe.
-func NewIPCache(cp cloudprovider.Interface, clock util.Clock) *ipCache {
+//
+// TODO: when we switch to go1.4, this class would be a good candidate for something
+// that could be produced from a template and a type via `go generate`.
+func NewIPCache(cp cloudprovider.Interface, clock util.Clock, ttl time.Duration) *ipCache {
 	return &ipCache{
 		clock:         clock,
 		cloudProvider: cp,
 		cache:         map[string]ipCacheEntry{},
+		ttl:           ttl,
 	}
 }
 
@@ -57,7 +62,7 @@ func (c *ipCache) GetInstanceIP(host string) string {
 	data, ok := c.cache[host]
 	now := c.clock.Now()
 
-	if !ok || now.Sub(data.lastUpdate) > (30*time.Second) {
+	if !ok || now.Sub(data.lastUpdate) > c.ttl {
 		ip := getInstanceIPFromCloud(c.cloudProvider, host)
 		data = ipCacheEntry{
 			ip:         ip,

pkg/master/ip_cache_test.go

@@ -28,16 +28,32 @@ func TestCacheExpire(t *testing.T) {
 	fakeCloud := &fake_cloud.FakeCloud{}
 	clock := &util.FakeClock{time.Now()}
 
-	c := NewIPCache(fakeCloud, clock)
+	c := NewIPCache(fakeCloud, clock, 60*time.Second)
 
 	_ = c.GetInstanceIP("foo")
 	// This call should hit the cache, so we expect no additional calls to the cloud
 	_ = c.GetInstanceIP("foo")
 	// Advance the clock, this call should miss the cache, so expect one more call.
-	clock.Time = clock.Time.Add(60 * time.Second)
+	clock.Time = clock.Time.Add(61 * time.Second)
 	_ = c.GetInstanceIP("foo")
 
 	if len(fakeCloud.Calls) != 2 || fakeCloud.Calls[1] != "ip-address" || fakeCloud.Calls[0] != "ip-address" {
 		t.Errorf("Unexpected calls: %+v", fakeCloud.Calls)
 	}
 }
+
+func TestCacheNotExpire(t *testing.T) {
+	fakeCloud := &fake_cloud.FakeCloud{}
+	clock := &util.FakeClock{time.Now()}
+
+	c := NewIPCache(fakeCloud, clock, 60*time.Second)
+
+	_ = c.GetInstanceIP("foo")
+	// This call should hit the cache, so we expect no additional calls to the cloud
+	clock.Time = clock.Time.Add(60 * time.Second)
+	_ = c.GetInstanceIP("foo")
+
+	if len(fakeCloud.Calls) != 1 || fakeCloud.Calls[0] != "ip-address" {
+		t.Errorf("Unexpected calls: %+v", fakeCloud.Calls)
+	}
+}

pkg/master/master.go

@@ -323,7 +323,7 @@ func (m *Master) init(c *Config) {
 	var authenticator = c.Authenticator
 
 	nodeRESTStorage := minion.NewREST(m.minionRegistry)
-	ipCache := NewIPCache(c.Cloud, util.RealClock{})
+	ipCache := NewIPCache(c.Cloud, util.RealClock{}, 30*time.Second)
 	podCache := NewPodCache(
 		ipCache,
 		c.KubeletClient,