-
Notifications
You must be signed in to change notification settings - Fork 0
/
main.go
221 lines (196 loc) · 7.42 KB
/
main.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
package main
import (
"fmt"
"github.com/kcz17/dimmer/config"
"github.com/kcz17/dimmer/filters"
"github.com/kcz17/dimmer/logging"
"github.com/kcz17/dimmer/offlinetraining"
"github.com/kcz17/dimmer/onlinetraining"
"github.com/kcz17/dimmer/pid"
"github.com/kcz17/dimmer/profiling"
"github.com/kcz17/dimmer/responsetimecollector"
"log"
)
// ResponseTimeCollectorRequestsWindow defines the number of requests from which
// the aggregate response time will be calculated for the PID control loop. As
// the control loop runs every second by default, this is set to 100, hence
// requiring a minimum of 100rps for non-negligible response times to be passed
// to the PID controller. This is justifiable as web servers tend to encounter
// load above 100rps.
const ResponseTimeCollectorRequestsWindow = 100
func main() {
conf := config.ReadConfig()
logger := initLogger(conf)
controlLoop := initControlLoop(
conf,
initPIDController(conf),
responsetimecollector.NewTachymeterCollector(ResponseTimeCollectorRequestsWindow),
logger,
)
// Filters used to selectively dim routes.
requestFilter := initRequestFilter(conf)
pathProbabilities := initPathProbabilities(conf)
onlineTrainingService, err := onlinetraining.NewOnlineTraining(
logger,
initPaths(conf),
pathProbabilities,
1,
)
if err != nil {
log.Fatalf("expected onlineTrainingService to return nil err; got err = %v", err)
}
var profiler *profiling.Profiler
if *conf.Dimming.Profiler.Enabled {
priorityFetcher, err := profiling.NewRedisPriorityFetcher(
*conf.Dimming.Profiler.Redis.Addr,
*conf.Dimming.Profiler.Redis.Password,
*conf.Dimming.Profiler.Redis.PrioritiesDB,
*conf.Dimming.Profiler.Redis.QueueDB,
)
if err != nil {
panic(fmt.Errorf("could not create RedisPriorityFetcher: %w", err))
}
profiler = &profiling.Profiler{
Priorities: priorityFetcher,
Requests: profiling.NewInfluxDBRequestWriter(
*conf.Dimming.Profiler.InfluxDB.Addr,
*conf.Dimming.Profiler.InfluxDB.Token,
*conf.Dimming.Profiler.InfluxDB.Org,
*conf.Dimming.Profiler.InfluxDB.Bucket,
),
Aggregator: profiling.NewProfiledRequestAggregator(),
LowPriorityDimmingProbability: *conf.Dimming.Profiler.Probabilities.Low,
LowPriorityDimmingProbabilityMultiplier: *conf.Dimming.Profiler.Probabilities.LowMultiplier,
HighPriorityDimmingProbability: *conf.Dimming.Profiler.Probabilities.High,
HighPriorityDimmingProbabilityMultiplier: *conf.Dimming.Profiler.Probabilities.HighMultiplier,
}
}
// Serve the reverse proxy with dimming control loop.
server := NewServer(&ServerOptions{
FrontendAddr: fmt.Sprintf(":%d", *conf.Connection.FrontendPort),
BackendAddr: fmt.Sprintf("%s:%d", *conf.Connection.BackendHost, *conf.Connection.BackendPort),
MaxConns: 2048,
ControlLoop: controlLoop,
RequestFilter: requestFilter,
PathProbabilities: pathProbabilities,
Logger: logger,
IsDimmingEnabled: *conf.Dimming.Enabled,
OnlineTrainingService: onlineTrainingService,
OfflineTrainingService: offlinetraining.NewOfflineTraining(),
IsProfilingEnabled: *conf.Dimming.Profiler.Enabled,
ProfilingService: profiler,
ProfilingSessionCookie: *conf.Dimming.Profiler.SessionCookie,
})
// Start the server in a goroutine so we can separately block the main
// thread on the following API server.
go func() {
if err := server.ListenAndServe(); err != nil {
panic(fmt.Sprintf("expected server.ListenAndServe() returns nil err; got err = %v", err))
}
}()
api := APIServer{Server: server}
if err := api.ListenAndServe(fmt.Sprintf(":%d", *conf.Connection.AdminPort)); err != nil {
panic(fmt.Errorf("expected api.ListenAndServe() returns nil err; got err = %w", err))
}
}
func initLogger(conf *config.Config) logging.Logger {
var logger logging.Logger
if *conf.Logging.Driver == "noop" {
logger = logging.NewNoopLogger()
} else if *conf.Logging.Driver == "stdout" {
logger = logging.NewStdoutLogger()
} else if *conf.Logging.Driver == "influxdb" {
logger = logging.NewInfluxDBLogger(
*conf.Logging.InfluxDB.Addr,
*conf.Logging.InfluxDB.Token,
*conf.Logging.InfluxDB.Org,
*conf.Logging.InfluxDB.Bucket,
)
} else {
log.Fatalf("expected env var LOGGER_DRIVER one of {noop, stdout, influxdb}; got %s", *conf.Logging.Driver)
}
return logger
}
func initPaths(conf *config.Config) []string {
var paths []string
for _, component := range conf.Dimming.DimmableComponents {
paths = append(paths, *component.Path)
}
return paths
}
func initRequestFilter(conf *config.Config) *filters.RequestFilter {
filter := filters.NewRequestFilter()
for _, component := range conf.Dimming.DimmableComponents {
if component.Method.ShouldMatchAll != nil && *component.Method.ShouldMatchAll {
filter.AddPathForAllMethods(*component.Path)
} else {
filter.AddPath(*component.Path, *component.Method.Method)
}
for _, exclusion := range component.Exclusions {
if err := filter.AddRefererExclusion(*component.Path, *exclusion.Method, *exclusion.Substring); err != nil {
log.Fatalf("expected filter.AddRefererExclusion(path=%s, method=%s, substring=%s) returns nil err; got err = %v", *component.Path, *exclusion.Method, *exclusion.Substring, err)
}
}
}
return filter
}
func initPathProbabilities(conf *config.Config) *filters.PathProbabilities {
// Set the defaultValue to 1 so we allow dimming by default for paths which
// are not in the probabilities list.
p, err := filters.NewPathProbabilities(1)
if err != nil {
panic(fmt.Sprintf("expected initPathProbabilities() returns nil err; got err = %v", err))
}
for _, component := range conf.Dimming.DimmableComponents {
if component.Probability != nil {
rule := filters.PathProbabilityRule{
Path: *component.Path,
Probability: *component.Probability,
}
if err := p.Set(rule); err != nil {
log.Fatalf("expected PathProbabilities.Set(rule=%+v) returns nil err; got err = %v", rule, err)
}
}
}
return p
}
func initPIDController(conf *config.Config) *pid.PIDController {
c, err := pid.NewPIDController(
pid.NewRealtimeClock(),
*conf.Dimming.Controller.Setpoint,
*conf.Dimming.Controller.Kp,
*conf.Dimming.Controller.Ki,
*conf.Dimming.Controller.Kd,
// isReversed is true as we want a positive error (i.e., actual response
// time below desired setpoint) to reduce the controller output.
true,
// minOutput is 0 as we do not want any dimming when the response time
// does not violate the desired setpoint.
0,
// maxOutput is 99 instead of 100 to ensure response times are collected
// during "full" dimming even if requests are only made to dimmed
// components.
99,
*conf.Dimming.Controller.SamplePeriod,
)
if err != nil {
log.Fatalf("expected controller.NewPIDController() returns nil err; got err = %v", err)
}
return c
}
func initControlLoop(
conf *config.Config,
pid *pid.PIDController,
responseTimeCollector responsetimecollector.Collector,
logger logging.Logger,
) *ServerControlLoop {
percentile := *conf.Dimming.Controller.Percentile
if percentile != "p50" && percentile != "p75" && percentile != "p95" {
log.Fatalf("expected environment variable CONTROLLER_PERCENTILE to be one of {p50|p75|p95}; got %s", percentile)
}
c, err := NewServerControlLoop(pid, responseTimeCollector, percentile, logger)
if err != nil {
log.Fatalf("expected NewServerControlLoop() returns nil err; got err = %v", err)
}
return c
}