Enable sloppy_tcp when DSR and Maglev is enabled

pkg/controllers/proxy/service_endpoints_sync.go

@@ -400,10 +400,33 @@ func (nsc *NetworkServicesController) setupExternalIPServices(serviceInfoMap ser
 			}
 		}
 	}
+	nsc.setupSloppyTCP(serviceInfoMap)
 
 	return nil
 }
 
+func (nsc *NetworkServicesController) setupSloppyTCP(serviceInfoMap serviceInfoMap) {
+	var sloppyTCPVal int8 = 0
+	for _, svc := range serviceInfoMap {
+		// Enable sloppy TCP if any DSR service with Maglev hashing is configured
+		if svc.directServerReturn && svc.scheduler == IpvsMaglevHashing {
+			sloppyTCPVal = 1
+			break
+		}
+	}
+
+	// enable/disable sloppy_tcp sysctl based on sloppyTCPVal
+	sloppyTCP := nsc.krNode.SloppyTCP()
+	if sloppyTCP.CachedVal() != sloppyTCPVal {
+		sysctlErr := sloppyTCP.WriteVal(sloppyTCPVal)
+		if sysctlErr != nil {
+			klog.Errorf("Failed to set IPVS sloppy TCP to %d: %s", sloppyTCPVal, sysctlErr.Error())
+			return
+		}
+		klog.Infof("IPVS sloppy TCP set to %d", sloppyTCPVal)
+	}
+}
+
 // setupExternalIPForService does the basic work to setup a non-DSR based external IP for service. This includes adding
 // the IPVS service to the host if it is missing, and setting up the dummy interface to be able to receive traffic on
 // the node.

pkg/utils/node.go

@@ -35,6 +35,7 @@ type LocalKRNode struct {
 	KRNode
 	NodeInterfaceName string
 	linkQ             LocalLinkQuerier
+	sloppyTCP         SysctlConfig
 }
 
 // NodeIPAware is an interface that provides methods to get the node's IP addresses in various data structures.
@@ -73,9 +74,14 @@ type NodeIPAndFamilyAware interface {
 	NodeFamilyAware
 }
 
+type NodeConfigAware interface {
+	SloppyTCP() *SysctlConfig
+}
+
 // NodeAware is an interface that combines the NodeIPAware, NodeInterfaceAware, NodeFamilyAware, and NodeNameAware
 // interfaces.
 type NodeAware interface {
+	NodeConfigAware
 	NodeIPAware
 	NodeInterfaceAware
 	NodeFamilyAware
@@ -127,6 +133,10 @@ func (n *KRNode) GetNodeName() string {
 	return n.NodeName
 }
 
+func (n *LocalKRNode) SloppyTCP() *SysctlConfig {
+	return &n.sloppyTCP
+}
+
 // FindBestIPv6NodeAddress returns the best available IPv6 address for the node. If the primary IP is already an IPv6
 // address, it will return that. Otherwise, it will return the first internal or external IPv6 address defined in the
 // Kubernetes Node Object.
@@ -241,6 +251,12 @@ func NewKRNode(node *apiv1.Node, linkQ LocalLinkQuerier, enableIPv4, enableIPv6
 		},
 		linkQ:             linkQ,
 		NodeInterfaceName: nodeInterfaceName,
+		// Purposefully set the value of sloppyTCP to 0. This ensures the machine's sloppy_tcp setting remains
+		// unchanged when there are no services with both Maglev and DSR enabled.
+		sloppyTCP: SysctlConfig{
+			name:  IPv4IPVSSloppyTCP,
+			value: 0,
+		},
 	}
 
 	return krNode, nil

pkg/utils/sysctl.go

@@ -13,6 +13,7 @@ const (
 	IPv4IPVSExpireNodestConn = "net/ipv4/vs/expire_nodest_conn"
 	IPv4IPVSExpireQuiescent  = "net/ipv4/vs/expire_quiescent_template"
 	IPv4IPVSConnReuseMode    = "net/ipv4/vs/conn_reuse_mode"
+	IPv4IPVSSloppyTCP        = "net/ipv4/vs/sloppy_tcp"
 	IPv4ConfAllArpIgnore     = "net/ipv4/conf/all/arp_ignore"
 	IPv4ConfAllArpAnnounce   = "net/ipv4/conf/all/arp_announce"
 	IPv6ConfAllDisableIPv6   = "net/ipv6/conf/all/disable_ipv6"
@@ -53,6 +54,24 @@ func (e *SysctlError) Unwrap() error {
 	return e.err
 }
 
+type SysctlConfig struct {
+	name  string
+	value int8
+}
+
+func (n *SysctlConfig) CachedVal() int8 {
+	return n.value
+}
+
+func (n *SysctlConfig) WriteVal(val int8) *SysctlError {
+	err := SetSysctl(n.name, int(val))
+	if err != nil {
+		return err
+	}
+	n.value = val
+	return nil
+}
+
 func sysctlStat(path string, hasValue bool, value int) (string, *SysctlError) {
 	sysctlPath := fmt.Sprintf("/proc/sys/%s", path)
 	if _, err := os.Stat(sysctlPath); err != nil {