update and use rs/dnscache implementation instead of custom (#13348)

additionally optimize for IP only setups, avoid doing
unnecessary lookups if the Dial addr is an IP.

allow support for multiple listeners on same socket,
this is mainly meant for future purposes.

cmd/common-main.go

@@ -51,7 +51,6 @@ import (
 	"github.com/minio/minio/internal/color"
 	"github.com/minio/minio/internal/config"
 	"github.com/minio/minio/internal/handlers"
-	xhttp "github.com/minio/minio/internal/http"
 	"github.com/minio/minio/internal/kms"
 	"github.com/minio/minio/internal/logger"
 	"github.com/minio/pkg/certs"
@@ -59,6 +58,7 @@ import (
 	"github.com/minio/pkg/ellipses"
 	"github.com/minio/pkg/env"
 	xnet "github.com/minio/pkg/net"
+	"github.com/rs/dnscache"
 )
 
 // serverDebugLog will enable debug printing
@@ -71,17 +71,34 @@ func init() {
 	logger.Init(GOPATH, GOROOT)
 	logger.RegisterError(config.FmtError)
 
-	if IsKubernetes() || IsDocker() || IsBOSH() || IsDCOS() || IsPCFTile() {
-		// 30 seconds matches the orchestrator DNS TTLs, have
-		// a 5 second timeout to lookup from DNS servers.
-		globalDNSCache = xhttp.NewDNSCache(30*time.Second, 5*time.Second, logger.LogOnceIf)
-	} else {
-		// On bare-metals DNS do not change often, so it is
-		// safe to assume a higher timeout upto 10 minutes.
-		globalDNSCache = xhttp.NewDNSCache(10*time.Minute, 5*time.Second, logger.LogOnceIf)
-	}
 	initGlobalContext()
 
+	options := dnscache.ResolverRefreshOptions{
+		ClearUnused:      true,
+		PersistOnFailure: false,
+	}
+
+	// Call to refresh will refresh names in cache. If you pass true, it will also
+	// remove cached names not looked up since the last call to Refresh. It is a good idea
+	// to call this method on a regular interval.
+	go func() {
+		var t *time.Ticker
+		if IsKubernetes() || IsDocker() || IsBOSH() || IsDCOS() || IsPCFTile() {
+			t = time.NewTicker(1 * time.Minute)
+		} else {
+			t = time.NewTicker(10 * time.Minute)
+		}
+		defer t.Stop()
+		for {
+			select {
+			case <-t.C:
+				globalDNSCache.RefreshWithOptions(options)
+			case <-GlobalContext.Done():
+				return
+			}
+		}
+	}()
+
 	globalForwarder = handlers.NewForwarder(&handlers.Forwarder{
 		PassHost:     true,
 		RoundTripper: newGatewayHTTPTransport(1 * time.Hour),