326 lines
11 KiB
Go
326 lines
11 KiB
Go
/*
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Copyright 2014 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package userspace
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import (
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"errors"
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"fmt"
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"net"
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"reflect"
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"strconv"
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"sync"
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"time"
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"github.com/golang/glog"
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"k8s.io/apimachinery/pkg/types"
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"k8s.io/kubernetes/pkg/api"
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"k8s.io/kubernetes/pkg/proxy"
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"k8s.io/kubernetes/pkg/util/slice"
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)
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var (
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ErrMissingServiceEntry = errors.New("missing service entry")
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ErrMissingEndpoints = errors.New("missing endpoints")
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)
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type affinityState struct {
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clientIP string
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//clientProtocol api.Protocol //not yet used
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//sessionCookie string //not yet used
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endpoint string
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lastUsed time.Time
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}
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type affinityPolicy struct {
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affinityType api.ServiceAffinity
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affinityMap map[string]*affinityState // map client IP -> affinity info
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ttlMinutes int
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}
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// LoadBalancerRR is a round-robin load balancer.
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type LoadBalancerRR struct {
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lock sync.RWMutex
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services map[proxy.ServicePortName]*balancerState
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}
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// Ensure this implements LoadBalancer.
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var _ LoadBalancer = &LoadBalancerRR{}
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type balancerState struct {
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endpoints []string // a list of "ip:port" style strings
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index int // current index into endpoints
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affinity affinityPolicy
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}
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func newAffinityPolicy(affinityType api.ServiceAffinity, ttlMinutes int) *affinityPolicy {
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return &affinityPolicy{
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affinityType: affinityType,
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affinityMap: make(map[string]*affinityState),
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ttlMinutes: ttlMinutes,
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}
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}
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// NewLoadBalancerRR returns a new LoadBalancerRR.
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func NewLoadBalancerRR() *LoadBalancerRR {
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return &LoadBalancerRR{
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services: map[proxy.ServicePortName]*balancerState{},
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}
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}
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func (lb *LoadBalancerRR) NewService(svcPort proxy.ServicePortName, affinityType api.ServiceAffinity, ttlMinutes int) error {
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glog.V(4).Infof("LoadBalancerRR NewService %q", svcPort)
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lb.lock.Lock()
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defer lb.lock.Unlock()
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lb.newServiceInternal(svcPort, affinityType, ttlMinutes)
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return nil
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}
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// This assumes that lb.lock is already held.
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func (lb *LoadBalancerRR) newServiceInternal(svcPort proxy.ServicePortName, affinityType api.ServiceAffinity, ttlMinutes int) *balancerState {
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if ttlMinutes == 0 {
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ttlMinutes = 180 //default to 3 hours if not specified. Should 0 be unlimited instead????
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}
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if _, exists := lb.services[svcPort]; !exists {
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lb.services[svcPort] = &balancerState{affinity: *newAffinityPolicy(affinityType, ttlMinutes)}
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glog.V(4).Infof("LoadBalancerRR service %q did not exist, created", svcPort)
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} else if affinityType != "" {
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lb.services[svcPort].affinity.affinityType = affinityType
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}
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return lb.services[svcPort]
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}
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func (lb *LoadBalancerRR) DeleteService(svcPort proxy.ServicePortName) {
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glog.V(4).Infof("LoadBalancerRR DeleteService %q", svcPort)
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lb.lock.Lock()
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defer lb.lock.Unlock()
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delete(lb.services, svcPort)
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}
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// return true if this service is using some form of session affinity.
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func isSessionAffinity(affinity *affinityPolicy) bool {
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// Should never be empty string, but checking for it to be safe.
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if affinity.affinityType == "" || affinity.affinityType == api.ServiceAffinityNone {
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return false
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}
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return true
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}
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// NextEndpoint returns a service endpoint.
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// The service endpoint is chosen using the round-robin algorithm.
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func (lb *LoadBalancerRR) NextEndpoint(svcPort proxy.ServicePortName, srcAddr net.Addr, sessionAffinityReset bool) (string, error) {
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// Coarse locking is simple. We can get more fine-grained if/when we
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// can prove it matters.
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lb.lock.Lock()
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defer lb.lock.Unlock()
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state, exists := lb.services[svcPort]
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if !exists || state == nil {
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return "", ErrMissingServiceEntry
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}
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if len(state.endpoints) == 0 {
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return "", ErrMissingEndpoints
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}
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glog.V(4).Infof("NextEndpoint for service %q, srcAddr=%v: endpoints: %+v", svcPort, srcAddr, state.endpoints)
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sessionAffinityEnabled := isSessionAffinity(&state.affinity)
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var ipaddr string
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if sessionAffinityEnabled {
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// Caution: don't shadow ipaddr
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var err error
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ipaddr, _, err = net.SplitHostPort(srcAddr.String())
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if err != nil {
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return "", fmt.Errorf("malformed source address %q: %v", srcAddr.String(), err)
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}
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if !sessionAffinityReset {
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sessionAffinity, exists := state.affinity.affinityMap[ipaddr]
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if exists && int(time.Now().Sub(sessionAffinity.lastUsed).Minutes()) < state.affinity.ttlMinutes {
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// Affinity wins.
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endpoint := sessionAffinity.endpoint
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sessionAffinity.lastUsed = time.Now()
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glog.V(4).Infof("NextEndpoint for service %q from IP %s with sessionAffinity %#v: %s", svcPort, ipaddr, sessionAffinity, endpoint)
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return endpoint, nil
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}
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}
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}
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// Take the next endpoint.
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endpoint := state.endpoints[state.index]
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state.index = (state.index + 1) % len(state.endpoints)
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if sessionAffinityEnabled {
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var affinity *affinityState
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affinity = state.affinity.affinityMap[ipaddr]
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if affinity == nil {
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affinity = new(affinityState) //&affinityState{ipaddr, "TCP", "", endpoint, time.Now()}
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state.affinity.affinityMap[ipaddr] = affinity
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}
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affinity.lastUsed = time.Now()
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affinity.endpoint = endpoint
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affinity.clientIP = ipaddr
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glog.V(4).Infof("Updated affinity key %s: %#v", ipaddr, state.affinity.affinityMap[ipaddr])
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}
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return endpoint, nil
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}
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type hostPortPair struct {
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host string
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port int
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}
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func isValidEndpoint(hpp *hostPortPair) bool {
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return hpp.host != "" && hpp.port > 0
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}
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func flattenValidEndpoints(endpoints []hostPortPair) []string {
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// Convert Endpoint objects into strings for easier use later. Ignore
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// the protocol field - we'll get that from the Service objects.
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var result []string
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for i := range endpoints {
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hpp := &endpoints[i]
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if isValidEndpoint(hpp) {
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result = append(result, net.JoinHostPort(hpp.host, strconv.Itoa(hpp.port)))
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}
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}
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return result
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}
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// Remove any session affinity records associated to a particular endpoint (for example when a pod goes down).
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func removeSessionAffinityByEndpoint(state *balancerState, svcPort proxy.ServicePortName, endpoint string) {
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for _, affinity := range state.affinity.affinityMap {
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if affinity.endpoint == endpoint {
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glog.V(4).Infof("Removing client: %s from affinityMap for service %q", affinity.endpoint, svcPort)
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delete(state.affinity.affinityMap, affinity.clientIP)
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}
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}
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}
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// Loop through the valid endpoints and then the endpoints associated with the Load Balancer.
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// Then remove any session affinity records that are not in both lists.
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// This assumes the lb.lock is held.
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func (lb *LoadBalancerRR) updateAffinityMap(svcPort proxy.ServicePortName, newEndpoints []string) {
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allEndpoints := map[string]int{}
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for _, newEndpoint := range newEndpoints {
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allEndpoints[newEndpoint] = 1
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}
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state, exists := lb.services[svcPort]
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if !exists {
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return
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}
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for _, existingEndpoint := range state.endpoints {
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allEndpoints[existingEndpoint] = allEndpoints[existingEndpoint] + 1
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}
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for mKey, mVal := range allEndpoints {
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if mVal == 1 {
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glog.V(2).Infof("Delete endpoint %s for service %q", mKey, svcPort)
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removeSessionAffinityByEndpoint(state, svcPort, mKey)
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}
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}
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}
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// OnEndpointsUpdate manages the registered service endpoints.
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// Registered endpoints are updated if found in the update set or
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// unregistered if missing from the update set.
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func (lb *LoadBalancerRR) OnEndpointsUpdate(allEndpoints []api.Endpoints) {
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registeredEndpoints := make(map[proxy.ServicePortName]bool)
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lb.lock.Lock()
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defer lb.lock.Unlock()
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// Update endpoints for services.
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for i := range allEndpoints {
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svcEndpoints := &allEndpoints[i]
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// We need to build a map of portname -> all ip:ports for that
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// portname. Explode Endpoints.Subsets[*] into this structure.
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portsToEndpoints := map[string][]hostPortPair{}
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for i := range svcEndpoints.Subsets {
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ss := &svcEndpoints.Subsets[i]
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for i := range ss.Ports {
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port := &ss.Ports[i]
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for i := range ss.Addresses {
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addr := &ss.Addresses[i]
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portsToEndpoints[port.Name] = append(portsToEndpoints[port.Name], hostPortPair{addr.IP, int(port.Port)})
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// Ignore the protocol field - we'll get that from the Service objects.
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}
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}
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}
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for portname := range portsToEndpoints {
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svcPort := proxy.ServicePortName{NamespacedName: types.NamespacedName{Namespace: svcEndpoints.Namespace, Name: svcEndpoints.Name}, Port: portname}
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state, exists := lb.services[svcPort]
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curEndpoints := []string{}
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if state != nil {
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curEndpoints = state.endpoints
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}
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newEndpoints := flattenValidEndpoints(portsToEndpoints[portname])
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if !exists || state == nil || len(curEndpoints) != len(newEndpoints) || !slicesEquiv(slice.CopyStrings(curEndpoints), newEndpoints) {
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glog.V(1).Infof("LoadBalancerRR: Setting endpoints for %s to %+v", svcPort, newEndpoints)
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lb.updateAffinityMap(svcPort, newEndpoints)
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// OnEndpointsUpdate can be called without NewService being called externally.
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// To be safe we will call it here. A new service will only be created
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// if one does not already exist. The affinity will be updated
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// later, once NewService is called.
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state = lb.newServiceInternal(svcPort, api.ServiceAffinity(""), 0)
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state.endpoints = slice.ShuffleStrings(newEndpoints)
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// Reset the round-robin index.
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state.index = 0
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}
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registeredEndpoints[svcPort] = true
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}
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}
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// Remove endpoints missing from the update.
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for k := range lb.services {
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if _, exists := registeredEndpoints[k]; !exists {
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glog.V(2).Infof("LoadBalancerRR: Removing endpoints for %s", k)
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// Reset but don't delete.
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state := lb.services[k]
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state.endpoints = []string{}
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state.index = 0
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state.affinity.affinityMap = map[string]*affinityState{}
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}
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}
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}
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// Tests whether two slices are equivalent. This sorts both slices in-place.
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func slicesEquiv(lhs, rhs []string) bool {
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if len(lhs) != len(rhs) {
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return false
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}
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if reflect.DeepEqual(slice.SortStrings(lhs), slice.SortStrings(rhs)) {
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return true
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}
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return false
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}
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func (lb *LoadBalancerRR) CleanupStaleStickySessions(svcPort proxy.ServicePortName) {
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lb.lock.Lock()
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defer lb.lock.Unlock()
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state, exists := lb.services[svcPort]
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if !exists {
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return
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}
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for ip, affinity := range state.affinity.affinityMap {
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if int(time.Now().Sub(affinity.lastUsed).Minutes()) >= state.affinity.ttlMinutes {
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glog.V(4).Infof("Removing client %s from affinityMap for service %q", affinity.clientIP, svcPort)
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delete(state.affinity.affinityMap, ip)
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}
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}
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}
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