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Commit d0853ee

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Merge pull request go-kit#504 from martinbaillie/master
Add Eureka service discovery implementation
2 parents 5d93a23 + 443f6ea commit d0853ee

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9 files changed

+702
-0
lines changed

9 files changed

+702
-0
lines changed

‎circle.yml‎

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@@ -24,3 +24,4 @@ test:
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ETCD_ADDR: http://localhost:2379
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CONSUL_ADDR: localhost:8500
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ZK_ADDR: localhost:2181
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EUREKA_ADDR: http://localhost:8761/eureka

‎docker-compose-integration.yml‎

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@@ -14,3 +14,9 @@ services:
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image: zookeeper
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ports:
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- "2181:2181"
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eureka:
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image: springcloud/eureka
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environment:
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eureka.server.responseCacheUpdateIntervalMs: 1000
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ports:
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- "8761:8761"

‎sd/eureka/doc.go‎

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// Package eureka provides subscriber and registrar implementations for Netflix OSS's Eureka
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package eureka

‎sd/eureka/integration_test.go‎

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// +build integration
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package eureka
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import (
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"io"
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"os"
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"testing"
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"time"
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11+
"github.com/hudl/fargo"
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"github.com/go-kit/kit/endpoint"
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"github.com/go-kit/kit/log"
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)
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// Package sd/eureka provides a wrapper around the Netflix Eureka service
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// registry by way of the Fargo library. This test assumes the user has an
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// instance of Eureka available at the address in the environment variable.
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// Example `${EUREKA_ADDR}` format: http://localhost:8761/eureka
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//
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// NOTE: when starting a Eureka server for integration testing, ensure
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// the response cache interval is reduced to one second. This can be
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// achieved with the following Java argument:
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// `-Deureka.server.responseCacheUpdateIntervalMs=1000`
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func TestIntegration(t *testing.T) {
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eurekaAddr := os.Getenv("EUREKA_ADDR")
28+
if eurekaAddr == "" {
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t.Skip("EUREKA_ADDR is not set")
30+
}
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logger := log.NewLogfmtLogger(os.Stderr)
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logger = log.With(logger, "ts", log.DefaultTimestamp)
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var fargoConfig fargo.Config
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// Target Eureka server(s).
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fargoConfig.Eureka.ServiceUrls = []string{eurekaAddr}
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// How often the subscriber should poll for updates.
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fargoConfig.Eureka.PollIntervalSeconds = 1
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// Create a Fargo connection and a Eureka registrar.
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fargoConnection := fargo.NewConnFromConfig(fargoConfig)
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registrar1 := NewRegistrar(&fargoConnection, instanceTest1, log.With(logger, "component", "registrar1"))
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// Register one instance.
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registrar1.Register()
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defer registrar1.Deregister()
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// This should be enough time for the Eureka server response cache to update.
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time.Sleep(time.Second)
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// Build a Eureka subscriber.
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factory := func(instance string) (endpoint.Endpoint, io.Closer, error) {
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t.Logf("factory invoked for %q", instance)
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return endpoint.Nop, nil, nil
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}
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s := NewSubscriber(
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&fargoConnection,
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appNameTest,
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factory,
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log.With(logger, "component", "subscriber"),
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)
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defer s.Stop()
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// We should have one endpoint immediately after subscriber instantiation.
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endpoints, err := s.Endpoints()
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if err != nil {
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t.Error(err)
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}
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if want, have := 1, len(endpoints); want != have {
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t.Errorf("want %d, have %d", want, have)
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}
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// Register a second instance
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registrar2 := NewRegistrar(&fargoConnection, instanceTest2, log.With(logger, "component", "registrar2"))
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registrar2.Register()
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defer registrar2.Deregister() // In case of exceptional circumstances.
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// This should be enough time for a scheduled update assuming Eureka is
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// configured with the properties mentioned in the function comments.
81+
time.Sleep(2 * time.Second)
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// Now we should have two endpoints.
84+
endpoints, err = s.Endpoints()
85+
if err != nil {
86+
t.Error(err)
87+
}
88+
if want, have := 2, len(endpoints); want != have {
89+
t.Errorf("want %d, have %d", want, have)
90+
}
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// Deregister the second instance.
93+
registrar2.Deregister()
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// Wait for another scheduled update.
96+
time.Sleep(2 * time.Second)
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// And then there was one.
99+
endpoints, err = s.Endpoints()
100+
if err != nil {
101+
t.Error(err)
102+
}
103+
if want, have := 1, len(endpoints); want != have {
104+
t.Errorf("want %d, have %d", want, have)
105+
}
106+
}

‎sd/eureka/registrar.go‎

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package eureka
2+
3+
import (
4+
"fmt"
5+
"net/http"
6+
"sync"
7+
"time"
8+
9+
"github.com/hudl/fargo"
10+
11+
"github.com/go-kit/kit/log"
12+
"github.com/go-kit/kit/sd"
13+
)
14+
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// Matches official Netflix Java client default.
16+
const defaultRenewalInterval = 30 * time.Second
17+
18+
// The methods of fargo.Connection used in this package.
19+
type fargoConnection interface {
20+
RegisterInstance(instance *fargo.Instance) error
21+
DeregisterInstance(instance *fargo.Instance) error
22+
ReregisterInstance(instance *fargo.Instance) error
23+
HeartBeatInstance(instance *fargo.Instance) error
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ScheduleAppUpdates(name string, await bool, done <-chan struct{}) <-chan fargo.AppUpdate
25+
GetApp(name string) (*fargo.Application, error)
26+
}
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type fargoUnsuccessfulHTTPResponse struct {
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statusCode int
30+
messagePrefix string
31+
}
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// Registrar maintains service instance liveness information in Eureka.
34+
type Registrar struct {
35+
conn fargoConnection
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instance *fargo.Instance
37+
logger log.Logger
38+
quitc chan chan struct{}
39+
sync.Mutex
40+
}
41+
42+
var _ sd.Registrar = (*Registrar)(nil)
43+
44+
// NewRegistrar returns an Eureka Registrar acting on behalf of the provided
45+
// Fargo connection and instance. See the integration test for usage examples.
46+
func NewRegistrar(conn fargoConnection, instance *fargo.Instance, logger log.Logger) *Registrar {
47+
return &Registrar{
48+
conn: conn,
49+
instance: instance,
50+
logger: log.With(logger, "service", instance.App, "address", fmt.Sprintf("%s:%d", instance.IPAddr, instance.Port)),
51+
}
52+
}
53+
54+
// Register implements sd.Registrar.
55+
func (r *Registrar) Register() {
56+
r.Lock()
57+
defer r.Unlock()
58+
59+
if r.quitc != nil {
60+
return // Already in the registration loop.
61+
}
62+
63+
if err := r.conn.RegisterInstance(r.instance); err != nil {
64+
r.logger.Log("during", "Register", "err", err)
65+
}
66+
67+
r.quitc = make(chan chan struct{})
68+
go r.loop()
69+
}
70+
71+
// Deregister implements sd.Registrar.
72+
func (r *Registrar) Deregister() {
73+
r.Lock()
74+
defer r.Unlock()
75+
76+
if r.quitc == nil {
77+
return // Already deregistered.
78+
}
79+
80+
q := make(chan struct{})
81+
r.quitc <- q
82+
<-q
83+
r.quitc = nil
84+
}
85+
86+
func (r *Registrar) loop() {
87+
var renewalInterval time.Duration
88+
if r.instance.LeaseInfo.RenewalIntervalInSecs > 0 {
89+
renewalInterval = time.Duration(r.instance.LeaseInfo.RenewalIntervalInSecs) * time.Second
90+
} else {
91+
renewalInterval = defaultRenewalInterval
92+
}
93+
ticker := time.NewTicker(renewalInterval)
94+
defer ticker.Stop()
95+
96+
for {
97+
select {
98+
case <-ticker.C:
99+
if err := r.heartbeat(); err != nil {
100+
r.logger.Log("during", "heartbeat", "err", err)
101+
}
102+
103+
case q := <-r.quitc:
104+
if err := r.conn.DeregisterInstance(r.instance); err != nil {
105+
r.logger.Log("during", "Deregister", "err", err)
106+
}
107+
close(q)
108+
return
109+
}
110+
}
111+
}
112+
113+
func (r *Registrar) heartbeat() error {
114+
err := r.conn.HeartBeatInstance(r.instance)
115+
if err != nil {
116+
if u, ok := err.(*fargoUnsuccessfulHTTPResponse); ok && u.statusCode == http.StatusNotFound {
117+
// Instance expired (e.g. network partition). Re-register.
118+
r.logger.Log("during", "heartbeat", err.Error())
119+
return r.conn.ReregisterInstance(r.instance)
120+
}
121+
}
122+
return err
123+
}
124+
125+
func (u *fargoUnsuccessfulHTTPResponse) Error() string {
126+
return fmt.Sprintf("err=%s code=%d", u.messagePrefix, u.statusCode)
127+
}

‎sd/eureka/registrar_test.go‎

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1+
package eureka
2+
3+
import (
4+
"testing"
5+
"time"
6+
)
7+
8+
func TestRegistrar(t *testing.T) {
9+
connection := &testConnection{
10+
errHeartbeat: errTest,
11+
}
12+
13+
registrar1 := NewRegistrar(connection, instanceTest1, loggerTest)
14+
registrar2 := NewRegistrar(connection, instanceTest2, loggerTest)
15+
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// Not registered.
17+
registrar1.Deregister()
18+
if want, have := 0, len(connection.instances); want != have {
19+
t.Errorf("want %d, have %d", want, have)
20+
}
21+
22+
// Register.
23+
registrar1.Register()
24+
if want, have := 1, len(connection.instances); want != have {
25+
t.Errorf("want %d, have %d", want, have)
26+
}
27+
28+
registrar2.Register()
29+
if want, have := 2, len(connection.instances); want != have {
30+
t.Errorf("want %d, have %d", want, have)
31+
}
32+
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// Deregister.
34+
registrar1.Deregister()
35+
if want, have := 1, len(connection.instances); want != have {
36+
t.Errorf("want %d, have %d", want, have)
37+
}
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// Already registered.
40+
registrar1.Register()
41+
if want, have := 2, len(connection.instances); want != have {
42+
t.Errorf("want %d, have %d", want, have)
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}
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registrar1.Register()
45+
if want, have := 2, len(connection.instances); want != have {
46+
t.Errorf("want %d, have %d", want, have)
47+
}
48+
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// Wait for a heartbeat failure.
50+
time.Sleep(1010 * time.Millisecond)
51+
if want, have := 2, len(connection.instances); want != have {
52+
t.Errorf("want %d, have %d", want, have)
53+
}
54+
registrar1.Deregister()
55+
if want, have := 1, len(connection.instances); want != have {
56+
t.Errorf("want %d, have %d", want, have)
57+
}
58+
}
59+
60+
func TestBadRegister(t *testing.T) {
61+
connection := &testConnection{
62+
errRegister: errTest,
63+
}
64+
65+
registrar := NewRegistrar(connection, instanceTest1, loggerTest)
66+
registrar.Register()
67+
if want, have := 0, len(connection.instances); want != have {
68+
t.Errorf("want %d, have %d", want, have)
69+
}
70+
}
71+
72+
func TestBadDeregister(t *testing.T) {
73+
connection := &testConnection{
74+
errDeregister: errTest,
75+
}
76+
77+
registrar := NewRegistrar(connection, instanceTest1, loggerTest)
78+
registrar.Register()
79+
if want, have := 1, len(connection.instances); want != have {
80+
t.Errorf("want %d, have %d", want, have)
81+
}
82+
registrar.Deregister()
83+
if want, have := 1, len(connection.instances); want != have {
84+
t.Errorf("want %d, have %d", want, have)
85+
}
86+
}
87+
88+
func TestExpiredInstance(t *testing.T) {
89+
connection := &testConnection{
90+
errHeartbeat: errNotFound,
91+
}
92+
93+
registrar := NewRegistrar(connection, instanceTest1, loggerTest)
94+
registrar.Register()
95+
96+
// Wait for a heartbeat failure.
97+
time.Sleep(1010 * time.Millisecond)
98+
99+
if want, have := 1, len(connection.instances); want != have {
100+
t.Errorf("want %d, have %d", want, have)
101+
}
102+
}

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