/
client.go
325 lines (266 loc) · 8.21 KB
/
client.go
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package eureka
import (
"errors"
"math/rand"
"os"
"os/signal"
"strings"
"sync"
"syscall"
"time"
)
const (
DEFAULT_SLEEP_INTERVALS = 3
)
var DefaultClient = new(Client)
// eureka client
type Client struct {
// eureka client config
config *EurekaClientConfig
// current client (instance) config
instance *InstanceVo
// eureka server base url list
serviceUrls []string
// applications int registry
// key: appId
// value: ApplicationVo
registryApps map[string]ApplicationVo
// for monitor system signal
signalChan chan os.Signal
mu sync.RWMutex
}
func (t *Client) Config(config *EurekaClientConfig) *Client {
t.config = config
return t
}
// user brief parameters to register instance
func (t *Client) Register(appId string, port int) *Client {
vo := DefaultInstanceVo()
vo.App = appId
vo.Status = STATUS_STARTING
vo.Port = positiveInt{Value: port, Enabled: "true"}
vo.VipAddress = strings.ToLower(appId)
vo.SecureVipAddress = strings.ToLower(appId)
t.instance = vo
return t
}
// user raw instanceVo to register instance
func (t *Client) RegisterVo(vo *InstanceVo) *Client {
t.instance = vo
return t
}
// Api for sending rest http to eureka server
func (t *Client) Api() (*EurekaServerApi, error) {
api, err := t.pickEurekaServerApi()
if err != nil {
return nil, err
}
return api, nil
}
func (t *Client) GetInstance() *InstanceVo {
return t.instance
}
func (t *Client) GetRegistryApps() map[string]ApplicationVo {
t.mu.RLock()
defer t.mu.RUnlock()
return t.registryApps
}
// start eureka client
// 1. parse/get service urls
// 2. register client to eureka server and send heartbeat
func (t *Client) Run() {
err := t.refreshServiceUrls()
if err != nil {
log.Errorf("Failed to refresh service urls, err=%s", err.Error())
return
}
// handle exit signal to de-register instance
go t.handleSignal()
// (if FetchRegistry is true), fetch registry apps periodically
// and update to t.registryApps
go t.refreshRegistry()
t.registerWithEureka()
}
func (t *Client) refreshServiceUrls() error {
err := t.getServiceUrlsWithZones()
if err != nil {
log.Errorf("Failed to init service urls, err=%s", err.Error())
return err
}
// auto update service urls
// (only) while userDnsForFetchingServiceUrls=true and AutoUpdateDnsServiceUrls=true
go func() {
if !t.config.UseDnsForFetchingServiceUrls && t.config.AutoUpdateDnsServiceUrls {
return
}
for {
t.getServiceUrlsWithZones()
time.Sleep(time.Duration(t.config.AutoUpdateDnsServiceUrlsIntervals) * time.Second)
log.Debugf("AutoUpdateDnsServiceUrls... ok")
}
}()
return nil
}
func (t *Client) getServiceUrlsWithZones() error {
availZones := t.config.GetAvailabilityZones(t.config.Region)
endpointUtils := new(EndpointUtils)
// loop to get zone's service urls
var err error
var urls []string
for _, zone := range availZones {
urls, err = endpointUtils.GetDiscoveryServiceUrls(t.config, zone)
if err != nil {
log.Errorf("Failed to boot eureka client, zone=%s, err=%s", zone, err.Error())
continue
}
t.mu.Lock()
t.mu.Unlock()
t.serviceUrls = urls
break
}
return err
}
// rand to pick service url
func (t *Client) pickServiceUrl() (string, bool) {
if len(t.serviceUrls) == 0 {
// if serviceUrls not init, try to fetch service urls one time
err := t.getServiceUrlsWithZones()
if err != nil {
return "", false
}
}
t.mu.RLock()
defer t.mu.RUnlock()
index := 0
if len(t.serviceUrls) > 1 {
index = rand.Intn(len(t.serviceUrls) - 1)
}
return t.serviceUrls[index], true
}
// rand to pick service url and new EurekaServerApi instance
func (t *Client) pickEurekaServerApi() (*EurekaServerApi, error) {
url, ok := t.pickServiceUrl()
if !ok {
log.Errorf("No service url is available to pick.")
return nil, errors.New("No service url is available to pick.")
}
return NewEurekaServerApi(url), nil
}
// register instance (default current status is STARTING)
// and update instance status to UP
func (t *Client) registerWithEureka() {
if !t.config.RegisterWithEureka {
return
}
// ensure client succeed to register to eureka server
for {
if t.instance == nil {
log.Errorf("Eureka instance can't be nil")
return
}
api, err := t.Api()
if err != nil {
time.Sleep(time.Second * DEFAULT_SLEEP_INTERVALS)
continue
}
instanceId, err := api.RegisterInstanceWithVo(t.instance)
if err != nil {
log.Errorf("Client register failed, err=%s", err.Error())
time.Sleep(time.Second * DEFAULT_SLEEP_INTERVALS)
continue
}
t.instance.InstanceId = instanceId
err = api.UpdateInstanceStatus(t.instance.App, t.instance.InstanceId, STATUS_UP)
if err != nil {
log.Errorf("Client UP failed, err=%s", err.Error())
time.Sleep(time.Second * DEFAULT_SLEEP_INTERVALS)
continue
}
// if success to register to eureka and update status tu UP
// then break loop
break;
}
// send heartbeat
t.heartbeat()
}
// eureka client heartbeat
func (t *Client) heartbeat() {
go func() {
for {
api, err := t.Api()
if err != nil {
time.Sleep(time.Second * DEFAULT_SLEEP_INTERVALS)
continue
}
err = api.SendHeartbeat(t.instance.App, t.instance.InstanceId)
if err != nil {
log.Errorf("Failed to send heartbeat, err=%s", err.Error())
time.Sleep(time.Second * DEFAULT_SLEEP_INTERVALS)
continue
}
log.Debugf("Heartbeat app=%s, instanceId=%s", t.instance.App, t.instance.InstanceId)
time.Sleep(time.Duration(t.config.HeartbeatIntervals) * time.Second)
}
}()
}
func (t *Client) refreshRegistry() {
if !t.config.FetchRegistry {
return
}
for {
t.fetchRegistry()
time.Sleep(time.Second * time.Duration(t.config.RegistryFetchIntervalSeconds))
}
}
func (t *Client) fetchRegistry() (map[string]ApplicationVo, error) {
api, err := t.Api()
if err != nil {
log.Errorf("Failed to QueryAllInstances, err=%s", err.Error())
return nil, err
}
apps, err := api.QueryAllInstances()
if err != nil {
log.Errorf("Failed to QueryAllInstances, err=%s", err.Error())
return nil, err
}
t.mu.Lock()
defer t.mu.Unlock()
// @TODO FilterOnlyUpInstances true,
t.registryApps = make(map[string]ApplicationVo)
for _, app := range apps {
t.registryApps[app.Name] = app
}
return t.registryApps, nil
}
// for graceful kill. Here handle SIGTERM signal to do sth
// e.g: kill -TERM $pid
// or "ctrl + c" to exit
func (t *Client) handleSignal() {
if t.signalChan == nil {
t.signalChan = make(chan os.Signal)
}
signal.Notify(t.signalChan, syscall.SIGTERM, syscall.SIGINT, syscall.SIGKILL)
for {
switch <-t.signalChan {
case syscall.SIGINT:
fallthrough
case syscall.SIGKILL:
fallthrough
case syscall.SIGTERM:
log.Infof("Receive exit signal, client instance going to de-register, instanceId=%s.", t.instance.InstanceId)
// de-register instance
api, err := t.Api()
if err != nil {
log.Errorf("Failed to get EurekaServerApi instance, de-register %s failed, err=%s", t.instance.InstanceId, err.Error())
return
}
err = api.DeRegisterInstance(t.instance.App, t.instance.InstanceId)
if err != nil {
log.Errorf("Failed to de-register %s, err=%s", t.instance.InstanceId, err.Error())
return
}
log.Infof("de-register %s success.", t.instance.InstanceId)
os.Exit(0)
}
}
}