forked from msazurestackworkloads/kubernetes
-
Notifications
You must be signed in to change notification settings - Fork 0
/
roundrobin.go
326 lines (287 loc) · 10.6 KB
/
roundrobin.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
/*
Copyright 2014 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package userspace
import (
"errors"
"fmt"
"net"
"reflect"
"strconv"
"sync"
"time"
"github.com/golang/glog"
"k8s.io/kubernetes/pkg/api"
"k8s.io/kubernetes/pkg/proxy"
"k8s.io/kubernetes/pkg/types"
"k8s.io/kubernetes/pkg/util/slice"
)
var (
ErrMissingServiceEntry = errors.New("missing service entry")
ErrMissingEndpoints = errors.New("missing endpoints")
)
type affinityState struct {
clientIP string
//clientProtocol api.Protocol //not yet used
//sessionCookie string //not yet used
endpoint string
lastUsed time.Time
}
type affinityPolicy struct {
affinityType api.ServiceAffinity
affinityMap map[string]*affinityState // map client IP -> affinity info
ttlMinutes int
}
// LoadBalancerRR is a round-robin load balancer.
type LoadBalancerRR struct {
lock sync.RWMutex
services map[proxy.ServicePortName]*balancerState
}
// Ensure this implements LoadBalancer.
var _ LoadBalancer = &LoadBalancerRR{}
type balancerState struct {
endpoints []string // a list of "ip:port" style strings
index int // current index into endpoints
affinity affinityPolicy
}
func newAffinityPolicy(affinityType api.ServiceAffinity, ttlMinutes int) *affinityPolicy {
return &affinityPolicy{
affinityType: affinityType,
affinityMap: make(map[string]*affinityState),
ttlMinutes: ttlMinutes,
}
}
// NewLoadBalancerRR returns a new LoadBalancerRR.
func NewLoadBalancerRR() *LoadBalancerRR {
return &LoadBalancerRR{
services: map[proxy.ServicePortName]*balancerState{},
}
}
func (lb *LoadBalancerRR) NewService(svcPort proxy.ServicePortName, affinityType api.ServiceAffinity, ttlMinutes int) error {
glog.V(4).Infof("LoadBalancerRR NewService %q", svcPort)
lb.lock.Lock()
defer lb.lock.Unlock()
lb.newServiceInternal(svcPort, affinityType, ttlMinutes)
return nil
}
// This assumes that lb.lock is already held.
func (lb *LoadBalancerRR) newServiceInternal(svcPort proxy.ServicePortName, affinityType api.ServiceAffinity, ttlMinutes int) *balancerState {
if ttlMinutes == 0 {
ttlMinutes = 180 //default to 3 hours if not specified. Should 0 be unlimited instead????
}
if _, exists := lb.services[svcPort]; !exists {
lb.services[svcPort] = &balancerState{affinity: *newAffinityPolicy(affinityType, ttlMinutes)}
glog.V(4).Infof("LoadBalancerRR service %q did not exist, created", svcPort)
} else if affinityType != "" {
lb.services[svcPort].affinity.affinityType = affinityType
}
return lb.services[svcPort]
}
func (lb *LoadBalancerRR) DeleteService(svcPort proxy.ServicePortName) {
glog.V(4).Infof("LoadBalancerRR DeleteService %q", svcPort)
lb.lock.Lock()
defer lb.lock.Unlock()
delete(lb.services, svcPort)
}
// return true if this service is using some form of session affinity.
func isSessionAffinity(affinity *affinityPolicy) bool {
// Should never be empty string, but checking for it to be safe.
if affinity.affinityType == "" || affinity.affinityType == api.ServiceAffinityNone {
return false
}
return true
}
// NextEndpoint returns a service endpoint.
// The service endpoint is chosen using the round-robin algorithm.
func (lb *LoadBalancerRR) NextEndpoint(svcPort proxy.ServicePortName, srcAddr net.Addr, sessionAffinityReset bool) (string, error) {
// Coarse locking is simple. We can get more fine-grained if/when we
// can prove it matters.
lb.lock.Lock()
defer lb.lock.Unlock()
state, exists := lb.services[svcPort]
if !exists || state == nil {
return "", ErrMissingServiceEntry
}
if len(state.endpoints) == 0 {
return "", ErrMissingEndpoints
}
glog.V(4).Infof("NextEndpoint for service %q, srcAddr=%v: endpoints: %+v", svcPort, srcAddr, state.endpoints)
sessionAffinityEnabled := isSessionAffinity(&state.affinity)
var ipaddr string
if sessionAffinityEnabled {
// Caution: don't shadow ipaddr
var err error
ipaddr, _, err = net.SplitHostPort(srcAddr.String())
if err != nil {
return "", fmt.Errorf("malformed source address %q: %v", srcAddr.String(), err)
}
if !sessionAffinityReset {
sessionAffinity, exists := state.affinity.affinityMap[ipaddr]
if exists && int(time.Now().Sub(sessionAffinity.lastUsed).Minutes()) < state.affinity.ttlMinutes {
// Affinity wins.
endpoint := sessionAffinity.endpoint
sessionAffinity.lastUsed = time.Now()
glog.V(4).Infof("NextEndpoint for service %q from IP %s with sessionAffinity %#v: %s", svcPort, ipaddr, sessionAffinity, endpoint)
return endpoint, nil
}
}
}
// Take the next endpoint.
endpoint := state.endpoints[state.index]
state.index = (state.index + 1) % len(state.endpoints)
if sessionAffinityEnabled {
var affinity *affinityState
affinity = state.affinity.affinityMap[ipaddr]
if affinity == nil {
affinity = new(affinityState) //&affinityState{ipaddr, "TCP", "", endpoint, time.Now()}
state.affinity.affinityMap[ipaddr] = affinity
}
affinity.lastUsed = time.Now()
affinity.endpoint = endpoint
affinity.clientIP = ipaddr
glog.V(4).Infof("Updated affinity key %s: %#v", ipaddr, state.affinity.affinityMap[ipaddr])
}
return endpoint, nil
}
type hostPortPair struct {
host string
port int
}
func isValidEndpoint(hpp *hostPortPair) bool {
return hpp.host != "" && hpp.port > 0
}
func flattenValidEndpoints(endpoints []hostPortPair) []string {
// Convert Endpoint objects into strings for easier use later. Ignore
// the protocol field - we'll get that from the Service objects.
var result []string
for i := range endpoints {
hpp := &endpoints[i]
if isValidEndpoint(hpp) {
result = append(result, net.JoinHostPort(hpp.host, strconv.Itoa(hpp.port)))
}
}
return result
}
// Remove any session affinity records associated to a particular endpoint (for example when a pod goes down).
func removeSessionAffinityByEndpoint(state *balancerState, svcPort proxy.ServicePortName, endpoint string) {
for _, affinity := range state.affinity.affinityMap {
if affinity.endpoint == endpoint {
glog.V(4).Infof("Removing client: %s from affinityMap for service %q", affinity.endpoint, svcPort)
delete(state.affinity.affinityMap, affinity.clientIP)
}
}
}
// Loop through the valid endpoints and then the endpoints associated with the Load Balancer.
// Then remove any session affinity records that are not in both lists.
// This assumes the lb.lock is held.
func (lb *LoadBalancerRR) updateAffinityMap(svcPort proxy.ServicePortName, newEndpoints []string) {
allEndpoints := map[string]int{}
for _, newEndpoint := range newEndpoints {
allEndpoints[newEndpoint] = 1
}
state, exists := lb.services[svcPort]
if !exists {
return
}
for _, existingEndpoint := range state.endpoints {
allEndpoints[existingEndpoint] = allEndpoints[existingEndpoint] + 1
}
for mKey, mVal := range allEndpoints {
if mVal == 1 {
glog.V(2).Infof("Delete endpoint %s for service %q", mKey, svcPort)
removeSessionAffinityByEndpoint(state, svcPort, mKey)
}
}
}
// OnEndpointsUpdate manages the registered service endpoints.
// Registered endpoints are updated if found in the update set or
// unregistered if missing from the update set.
func (lb *LoadBalancerRR) OnEndpointsUpdate(allEndpoints []api.Endpoints) {
registeredEndpoints := make(map[proxy.ServicePortName]bool)
lb.lock.Lock()
defer lb.lock.Unlock()
// Update endpoints for services.
for i := range allEndpoints {
svcEndpoints := &allEndpoints[i]
// We need to build a map of portname -> all ip:ports for that
// portname. Explode Endpoints.Subsets[*] into this structure.
portsToEndpoints := map[string][]hostPortPair{}
for i := range svcEndpoints.Subsets {
ss := &svcEndpoints.Subsets[i]
for i := range ss.Ports {
port := &ss.Ports[i]
for i := range ss.Addresses {
addr := &ss.Addresses[i]
portsToEndpoints[port.Name] = append(portsToEndpoints[port.Name], hostPortPair{addr.IP, int(port.Port)})
// Ignore the protocol field - we'll get that from the Service objects.
}
}
}
for portname := range portsToEndpoints {
svcPort := proxy.ServicePortName{NamespacedName: types.NamespacedName{Namespace: svcEndpoints.Namespace, Name: svcEndpoints.Name}, Port: portname}
state, exists := lb.services[svcPort]
curEndpoints := []string{}
if state != nil {
curEndpoints = state.endpoints
}
newEndpoints := flattenValidEndpoints(portsToEndpoints[portname])
if !exists || state == nil || len(curEndpoints) != len(newEndpoints) || !slicesEquiv(slice.CopyStrings(curEndpoints), newEndpoints) {
glog.V(1).Infof("LoadBalancerRR: Setting endpoints for %s to %+v", svcPort, newEndpoints)
lb.updateAffinityMap(svcPort, newEndpoints)
// OnEndpointsUpdate can be called without NewService being called externally.
// To be safe we will call it here. A new service will only be created
// if one does not already exist. The affinity will be updated
// later, once NewService is called.
state = lb.newServiceInternal(svcPort, api.ServiceAffinity(""), 0)
state.endpoints = slice.ShuffleStrings(newEndpoints)
// Reset the round-robin index.
state.index = 0
}
registeredEndpoints[svcPort] = true
}
}
// Remove endpoints missing from the update.
for k := range lb.services {
if _, exists := registeredEndpoints[k]; !exists {
glog.V(2).Infof("LoadBalancerRR: Removing endpoints for %s", k)
// Reset but don't delete.
state := lb.services[k]
state.endpoints = []string{}
state.index = 0
state.affinity.affinityMap = map[string]*affinityState{}
}
}
}
// Tests whether two slices are equivalent. This sorts both slices in-place.
func slicesEquiv(lhs, rhs []string) bool {
if len(lhs) != len(rhs) {
return false
}
if reflect.DeepEqual(slice.SortStrings(lhs), slice.SortStrings(rhs)) {
return true
}
return false
}
func (lb *LoadBalancerRR) CleanupStaleStickySessions(svcPort proxy.ServicePortName) {
lb.lock.Lock()
defer lb.lock.Unlock()
state, exists := lb.services[svcPort]
if !exists {
return
}
for ip, affinity := range state.affinity.affinityMap {
if int(time.Now().Sub(affinity.lastUsed).Minutes()) >= state.affinity.ttlMinutes {
glog.V(4).Infof("Removing client %s from affinityMap for service %q", affinity.clientIP, svcPort)
delete(state.affinity.affinityMap, ip)
}
}
}