Merge pull request #51682 from m1093782566/ipvs-rsync-iptables

Automatic merge from submit-queue

rsync IPVS proxier to the HEAD of iptables

**What this PR does / why we need it**:

There was a significant performance improvement made to iptables. Since IPVS proxier makes use of iptables in some use cases, I think we should rsync IPVS proxier to the HEAD of iptables.

**Which issue this PR fixes** : 

xref #51679 

**Special notes for your reviewer**:

**Release note**:

```release-note
NONE
```

pkg/proxy/ipvs/proxier.go

@@ -126,6 +126,11 @@ type Proxier struct {
 	ipvsScheduler  string
 	// Added as a member to the struct to allow injection for testing.
 	ipGetter IPGetter
+	// The following buffers are used to reuse memory and avoid allocations
+	// that are significantly impacting performance.
+	iptablesData *bytes.Buffer
+	natChains    *bytes.Buffer
+	natRules     *bytes.Buffer
 }
 
 // IPGetter helps get node network interface IP
@@ -268,6 +273,9 @@ func NewProxier(ipt utiliptables.Interface, ipvs utilipvs.Interface,
 		ipvs:             ipvs,
 		ipvsScheduler:    scheduler,
 		ipGetter:         &realIPGetter{},
+		iptablesData:     bytes.NewBuffer(nil),
+		natChains:        bytes.NewBuffer(nil),
+		natRules:         bytes.NewBuffer(nil),
 	}, nil
 }
 
@@ -859,28 +867,30 @@ func (proxier *Proxier) syncProxyRules(reason syncReason) {
 	// Get iptables-save output so we can check for existing chains and rules.
 	// This will be a map of chain name to chain with rules as stored in iptables-save/iptables-restore
 	existingNATChains := make(map[utiliptables.Chain]string)
-	iptablesData := bytes.NewBuffer(nil)
-	err := proxier.iptables.SaveInto(utiliptables.TableNAT, iptablesData)
+	proxier.iptablesData.Reset()
+	err := proxier.iptables.SaveInto(utiliptables.TableNAT, proxier.iptablesData)
 	if err != nil { // if we failed to get any rules
 		glog.Errorf("Failed to execute iptables-save, syncing all rules: %v", err)
 	} else { // otherwise parse the output
-		existingNATChains = utiliptables.GetChainLines(utiliptables.TableNAT, iptablesData.Bytes())
+		existingNATChains = utiliptables.GetChainLines(utiliptables.TableNAT, proxier.iptablesData.Bytes())
 	}
-	natChains := bytes.NewBuffer(nil)
-	natRules := bytes.NewBuffer(nil)
+	// Reset all buffers used later.
+	// This is to avoid memory reallocations and thus improve performance.
+	proxier.natChains.Reset()
+	proxier.natRules.Reset()
 	// Write table headers.
-	writeLine(natChains, "*nat")
+	writeLine(proxier.natChains, "*nat")
 	// Make sure we keep stats for the top-level chains, if they existed
 	// (which most should have because we created them above).
 	if chain, ok := existingNATChains[kubePostroutingChain]; ok {
-		writeLine(natChains, chain)
+		writeLine(proxier.natChains, chain)
 	} else {
-		writeLine(natChains, utiliptables.MakeChainLine(kubePostroutingChain))
+		writeLine(proxier.natChains, utiliptables.MakeChainLine(kubePostroutingChain))
 	}
 	// Install the kubernetes-specific postrouting rules. We use a whole chain for
 	// this so that it is easier to flush and change, for example if the mark
 	// value should ever change.
-	writeLine(natRules, []string{
+	writeLine(proxier.natRules, []string{
 		"-A", string(kubePostroutingChain),
 		"-m", "comment", "--comment", `"kubernetes service traffic requiring SNAT"`,
 		"-m", "mark", "--mark", proxier.masqueradeMark,
@@ -888,14 +898,14 @@ func (proxier *Proxier) syncProxyRules(reason syncReason) {
 	}...)
 
 	if chain, ok := existingNATChains[KubeMarkMasqChain]; ok {
-		writeLine(natChains, chain)
+		writeLine(proxier.natChains, chain)
 	} else {
-		writeLine(natChains, utiliptables.MakeChainLine(KubeMarkMasqChain))
+		writeLine(proxier.natChains, utiliptables.MakeChainLine(KubeMarkMasqChain))
 	}
 	// Install the kubernetes-specific masquerade mark rule. We use a whole chain for
 	// this so that it is easier to flush and change, for example if the mark
 	// value should ever change.
-	writeLine(natRules, []string{
+	writeLine(proxier.natRules, []string{
 		"-A", string(KubeMarkMasqChain),
 		"-j", "MARK", "--set-xmark", proxier.masqueradeMark,
 	}...)
@@ -915,6 +925,18 @@ func (proxier *Proxier) syncProxyRules(reason syncReason) {
 	// currentIPVSServices represent IPVS services listed from the system
 	currentIPVSServices := make(map[string]*utilipvs.VirtualServer)
 
+	// We are creating those slices ones here to avoid memory reallocations
+	// in every loop. Note that reuse the memory, instead of doing:
+	//   slice = <some new slice>
+	// you should always do one of the below:
+	//   slice = slice[:0] // and then append to it
+	//   slice = append(slice[:0], ...)
+	// To avoid growing this slice, we arbitrarily set its size to 64,
+	// there is never more than that many arguments for a single line.
+	// Note that even if we go over 64, it will still be correct - it
+	// is just for efficiency, not correctness.
+	args := make([]string, 64)
+
 	// Build IPVS rules for each service.
 	for svcName, svcInfo := range proxier.serviceMap {
 		protocol := strings.ToLower(string(svcInfo.protocol))
@@ -945,30 +967,30 @@ func (proxier *Proxier) syncProxyRules(reason syncReason) {
 			glog.Errorf("Failed to sync service: %v, err: %v", serv, err)
 		}
 		// Install masquerade rules if 'masqueradeAll' or 'clusterCIDR' is specified.
-		args := []string{
+		args = append(args[:0],
 			"-A", string(kubeServicesChain),
 			"-m", "comment", "--comment", fmt.Sprintf(`"%s cluster IP"`, svcNameString),
 			"-m", protocol, "-p", protocol,
 			"-d", fmt.Sprintf("%s/32", svcInfo.clusterIP.String()),
 			"--dport", strconv.Itoa(svcInfo.port),
-		}
+		)
 		if proxier.masqueradeAll {
-			err = proxier.linkKubeServiceChain(existingNATChains, natChains)
+			err = proxier.linkKubeServiceChain(existingNATChains, proxier.natChains)
 			if err != nil {
 				glog.Errorf("Failed to link KUBE-SERVICES chain: %v", err)
 			}
-			writeLine(natRules, append(args, "-j", string(KubeMarkMasqChain))...)
+			writeLine(proxier.natRules, append(args, "-j", string(KubeMarkMasqChain))...)
 		} else if len(proxier.clusterCIDR) > 0 {
 			// This masquerades off-cluster traffic to a service VIP.  The idea
 			// is that you can establish a static route for your Service range,
 			// routing to any node, and that node will bridge into the Service
 			// for you.  Since that might bounce off-node, we masquerade here.
 			// If/when we support "Local" policy for VIPs, we should update this.
-			err = proxier.linkKubeServiceChain(existingNATChains, natChains)
+			err = proxier.linkKubeServiceChain(existingNATChains, proxier.natChains)
 			if err != nil {
 				glog.Errorf("Failed to link KUBE-SERVICES chain: %v", err)
 			}
-			writeLine(natRules, append(args, "! -s", proxier.clusterCIDR, "-j", string(KubeMarkMasqChain))...)
+			writeLine(proxier.natRules, append(args, "! -s", proxier.clusterCIDR, "-j", string(KubeMarkMasqChain))...)
 		}
 
 		// Capture externalIPs.
@@ -1029,24 +1051,24 @@ func (proxier *Proxier) syncProxyRules(reason syncReason) {
 		for _, ingress := range svcInfo.loadBalancerStatus.Ingress {
 			if ingress.IP != "" {
 				if len(svcInfo.loadBalancerSourceRanges) != 0 {
-					err = proxier.linkKubeServiceChain(existingNATChains, natChains)
+					err = proxier.linkKubeServiceChain(existingNATChains, proxier.natChains)
 					if err != nil {
 						glog.Errorf("Failed to link KUBE-SERVICES chain: %v", err)
 					}
 					// The service firewall rules are created based on ServiceSpec.loadBalancerSourceRanges field.
 					// This currently works for loadbalancers that preserves source ips.
 					// For loadbalancers which direct traffic to service NodePort, the firewall rules will not apply.
-					args := []string{
+					args = append(args[:0],
 						"-A", string(kubeServicesChain),
 						"-m", "comment", "--comment", fmt.Sprintf(`"%s loadbalancer IP"`, svcNameString),
 						"-m", string(svcInfo.protocol), "-p", string(svcInfo.protocol),
 						"-d", fmt.Sprintf("%s/32", ingress.IP),
 						"--dport", fmt.Sprintf("%d", svcInfo.port),
-					}
+					)
 
 					allowFromNode := false
 					for _, src := range svcInfo.loadBalancerSourceRanges {
-						writeLine(natRules, append(args, "-s", src, "-j", "ACCEPT")...)
+						writeLine(proxier.natRules, append(args, "-s", src, "-j", "ACCEPT")...)
 						// ignore error because it has been validated
 						_, cidr, _ := net.ParseCIDR(src)
 						if cidr.Contains(proxier.nodeIP) {
@@ -1057,12 +1079,12 @@ func (proxier *Proxier) syncProxyRules(reason syncReason) {
 					// loadbalancer's backend hosts. In this case, request will not hit the loadbalancer but loop back directly.
 					// Need to add the following rule to allow request on host.
 					if allowFromNode {
-						writeLine(natRules, append(args, "-s", fmt.Sprintf("%s/32", ingress.IP), "-j", "ACCEPT")...)
+						writeLine(proxier.natRules, append(args, "-s", fmt.Sprintf("%s/32", ingress.IP), "-j", "ACCEPT")...)
 					}
 
 					// If the packet was able to reach the end of firewall chain, then it did not get DNATed.
 					// It means the packet cannot go through the firewall, then DROP it.
-					writeLine(natRules, append(args, "-j", string(KubeMarkDropChain))...)
+					writeLine(proxier.natRules, append(args, "-j", string(KubeMarkDropChain))...)
 				}
 
 				serv := &utilipvs.VirtualServer{
@@ -1140,11 +1162,11 @@ func (proxier *Proxier) syncProxyRules(reason syncReason) {
 	}
 
 	// Write the end-of-table markers.
-	writeLine(natRules, "COMMIT")
+	writeLine(proxier.natRules, "COMMIT")
 
 	// Sync iptables rules.
 	// NOTE: NoFlushTables is used so we don't flush non-kubernetes chains in the table.
-	natLines := append(natChains.Bytes(), natRules.Bytes()...)
+	natLines := append(proxier.natChains.Bytes(), proxier.natRules.Bytes()...)
 	lines := natLines
 
 	glog.V(3).Infof("Restoring iptables rules: %s", lines)

pkg/proxy/ipvs/proxier_test.go

@@ -19,6 +19,7 @@ limitations under the License.
 package ipvs
 
 import (
+	"bytes"
 	"net"
 	"reflect"
 	"testing"
@@ -112,6 +113,9 @@ func NewFakeProxier(ipt utiliptables.Interface, ipvs utilipvs.Interface, nodeIPs
 		healthChecker:    newFakeHealthChecker(),
 		ipvsScheduler:    DefaultScheduler,
 		ipGetter:         &fakeIPGetter{nodeIPs: nodeIPs},
+		iptablesData:     bytes.NewBuffer(nil),
+		natChains:        bytes.NewBuffer(nil),
+		natRules:         bytes.NewBuffer(nil),
 	}
 }