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eurekamirror.go
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eurekamirror.go
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// Copyright 2017 Istio 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.
// Mirrors Kubernetes endpoint instances into an Eureka server.
//
// The Eureka mirror process watches endpoints in Kubernetes, converts
// endpoint instances to Eureka instances and maintains their registration
// with an Eureka server. The Eureka mirror processes the corresponding
// pod labels for the endpoint instances and converts them into Eureka
// metadata during the conversion.
//
// TODO: reduce dup between Eureka clients here and inside the Eureka adapter
package main
import (
"bytes"
"encoding/json"
"flag"
"fmt"
"log"
"net/http"
"os"
"os/signal"
"syscall"
"time"
"k8s.io/api/core/v1"
meta_v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/runtime"
"k8s.io/apimachinery/pkg/watch"
"k8s.io/client-go/tools/cache"
"istio.io/istio/pilot/pkg/model"
"istio.io/istio/pilot/pkg/serviceregistry/kube"
)
var (
kubeconfig string
eurekaURL string
namespace string
)
func init() {
flag.StringVar(&kubeconfig, "kubeconfig", "",
"Use a Kubernetes configuration file instead of in-cluster configuration")
flag.StringVar(&eurekaURL, "url", "",
"Eureka server url")
flag.StringVar(&namespace, "namespace", "",
"Select a namespace for the controller loop. If not set, uses ${POD_NAMESPACE} environment variable")
}
type registerInstance struct {
Instance instance `json:"instance"`
}
type instance struct { // nolint: maligned
ID string `json:"instanceId,omitempty"`
Hostname string `json:"hostName"`
App string `json:"app"`
IPAddress string `json:"ipAddr"`
Port port `json:"port,omitempty"`
SecurePort port `json:"securePort,omitempty"`
Metadata metadata `json:"metadata,omitempty"`
}
type port struct {
Port int `json:"$,string"`
Enabled bool `json:"@enabled,string"`
}
type metadata map[string]string
const (
heartbeatInterval = 30 * time.Second
retryInterval = 10 * time.Second
appPath = "%s/eureka/v2/apps/%s"
instancePath = "%s/eureka/v2/apps/%s/%s"
)
// agent is a simple state machine that maintains an instance's registration with Eureka.
type agent struct {
stop <-chan struct{}
client http.Client
url string
instance *instance
}
func maintainRegistration(url string, client http.Client, inst *instance, stop <-chan struct{}) {
log.Println("Starting registration agent for", inst.ID, "with hostname", inst.Hostname)
a := &agent{
stop: stop,
client: client,
url: url,
instance: inst,
}
go a.unregistered()
<-stop
}
func (a *agent) unregistered() {
var retry, heartbeatDelay <-chan time.Time
if err := a.register(); err != nil {
log.Println(err)
retry = time.After(retryInterval)
} else {
heartbeatDelay = time.After(heartbeatInterval)
}
select {
case <-retry:
go a.unregistered() // attempt to re-register
case <-heartbeatDelay:
go a.registered() // start heartbeating
case <-a.stop:
log.Println("Stopping registration agent", a.instance.ID, "with hostname", a.instance.Hostname)
return
}
}
func (a *agent) registered() {
var retry, heartbeatDelay <-chan time.Time
if err := a.heartbeat(); err != nil {
log.Println(err)
retry = time.After(retryInterval)
} else {
heartbeatDelay = time.After(heartbeatInterval)
}
select { // TODO: unregistered vs heartbeat failure
case <-retry:
go a.unregistered()
case <-heartbeatDelay:
go a.registered()
case <-a.stop:
// attempt to unregister before terminating
if err := a.unregister(); err != nil {
log.Println(err)
}
log.Println("Stopping registration agent", a.instance.ID, "with hostname", a.instance.Hostname)
return
}
}
func (a *agent) register() error {
payload := registerInstance{Instance: *a.instance}
data, err := json.Marshal(&payload)
if err != nil {
return err
}
req, err := http.NewRequest(http.MethodPost, a.buildRegisterPath(), bytes.NewBuffer(data))
if err != nil {
return err
}
req.Header.Set("Content-type", "application/json")
resp, err := a.client.Do(req)
if err != nil {
return err
}
defer resp.Body.Close() // nolint: errcheck
if resp.StatusCode != http.StatusNoContent {
return fmt.Errorf("unexpected status code %s", resp.Status)
}
return nil
}
func (a *agent) heartbeat() error {
req, err := http.NewRequest(http.MethodPut, a.buildInstancePath(), nil)
if err != nil {
return err
}
resp, err := a.client.Do(req)
if err != nil {
return err
}
defer resp.Body.Close() // nolint: errcheck
if resp.StatusCode != http.StatusOK {
return fmt.Errorf("unexpected status code %s", resp.Status)
}
return nil
}
func (a *agent) unregister() error {
req, err := http.NewRequest(http.MethodDelete, a.buildInstancePath(), nil)
if err != nil {
return err
}
resp, err := a.client.Do(req)
if err != nil {
return err
}
if resp.StatusCode != http.StatusOK {
return fmt.Errorf("failed to unregister %s, got %s", a.instance.ID, resp.Status)
}
return nil
}
func (a *agent) buildRegisterPath() string {
return fmt.Sprintf(appPath, a.url, a.instance.App)
}
func (a *agent) buildInstancePath() string {
return fmt.Sprintf(instancePath, a.url, a.instance.App, a.instance.ID)
}
type eventKind int
const (
addEvent eventKind = iota
deleteEvent
)
type event struct {
kind eventKind
obj interface{}
}
// mirrors k8s instances to an Eureka server
// TODO: this may need flow control if enough events are being generated
type mirror struct {
url string
// mapping of endpoint name to instance id
agents map[string]map[string]chan struct{}
// mapping of ip to pod name
podCache map[string]string
podStore cache.Store
}
func maintainMirror(url string, podStore cache.Store, events <-chan event) {
m := &mirror{
url: url,
agents: make(map[string]map[string]chan struct{}),
podStore: podStore,
podCache: make(map[string]string),
}
m.sync(events)
}
func (m *mirror) sync(events <-chan event) {
for ev := range events {
switch ev.obj.(type) {
case *v1.Endpoints:
endpoint := ev.obj.(*v1.Endpoints)
switch ev.kind {
case addEvent:
instances := m.convertEndpoints(endpoint)
newIDs := make(map[string]bool)
for _, instance := range instances {
newIDs[instance.ID] = true
}
agents, exists := m.agents[endpoint.Name]
if !exists {
m.agents[endpoint.Name] = make(map[string]chan struct{})
agents = m.agents[endpoint.Name]
}
// remove instances that are gone
toRemove := make([]string, 0)
for id := range agents {
if !newIDs[id] {
toRemove = append(toRemove, id)
}
}
for _, id := range toRemove {
m.stopAgent(endpoint.Name, id)
}
// add instances that are new
for _, instance := range instances {
if _, exists := agents[instance.ID]; !exists {
m.startAgent(endpoint.Name, instance)
}
}
case deleteEvent:
for id := range m.agents[endpoint.Name] {
m.stopAgent(endpoint.Name, id)
}
delete(m.agents, endpoint.Name)
}
case *v1.Pod:
pod := ev.obj.(*v1.Pod)
switch ev.kind {
case addEvent:
if pod.Status.PodIP != "" {
m.podCache[pod.Status.PodIP] = podKey(pod)
}
case deleteEvent:
delete(m.podCache, podKey(pod))
}
}
}
// cleanup registration agents
for name := range m.agents {
for id := range m.agents[name] {
m.stopAgent(name, id)
}
}
}
func (m *mirror) convertEndpoints(ep *v1.Endpoints) []*instance {
instances := make([]*instance, 0)
for _, ss := range ep.Subsets {
for _, addr := range ss.Addresses {
for _, ssPort := range ss.Ports {
md := make(metadata)
// add labels
pod, exists := m.getPodByIP(addr.IP)
if exists {
for k, v := range pod.Labels {
md[k] = v
}
}
// add protocol labels
protocol := kube.ConvertProtocol(ssPort.Name, ssPort.Protocol)
switch protocol {
case model.ProtocolUDP:
md["istio.protocol"] = "udp"
case model.ProtocolTCP:
md["istio.protocol"] = "tcp"
case model.ProtocolHTTP:
md["istio.protocol"] = "http"
case model.ProtocolHTTP2:
md["istio.protocol"] = "http2"
case model.ProtocolHTTPS:
md["istio.protocol"] = "https"
case model.ProtocolGRPC:
md["istio.protocol"] = "grpc"
}
instances = append(instances, &instance{
ID: fmt.Sprintf("%s-%s-%d", ep.ObjectMeta.Name, addr.IP, ssPort.Port),
App: ep.ObjectMeta.Name,
Hostname: fmt.Sprintf("%s.%s.svc.cluster.local", ep.Name, ep.Namespace),
IPAddress: addr.IP,
Port: port{
Port: int(ssPort.Port),
Enabled: true,
},
Metadata: md,
})
}
}
}
return instances
}
func (m *mirror) getPodByIP(addr string) (*v1.Pod, bool) {
name, exists := m.podCache[addr]
if !exists {
return nil, false
}
obj, exists, err := m.podStore.GetByKey(name)
if err != nil {
log.Println(err)
}
if !exists {
return nil, false
}
return obj.(*v1.Pod), true
}
func (m *mirror) startAgent(name string, inst *instance) {
stop := make(chan struct{})
m.agents[name][inst.ID] = stop
go maintainRegistration(m.url, http.Client{Timeout: 15 * time.Second}, inst, stop)
}
func (m *mirror) stopAgent(name, id string) {
close(m.agents[name][id])
delete(m.agents[name], id)
}
func podKey(pod *v1.Pod) string {
return pod.Namespace + "/" + pod.Name
}
func main() {
flag.Parse()
_, client, err := kube.CreateInterface(kubeconfig)
if err != nil {
log.Println(err)
return
}
events := make(chan event)
handler := cache.ResourceEventHandlerFuncs{
AddFunc: func(obj interface{}) {
events <- event{addEvent, obj}
},
UpdateFunc: func(old, cur interface{}) {
events <- event{deleteEvent, old}
events <- event{addEvent, cur}
},
DeleteFunc: func(obj interface{}) {
events <- event{deleteEvent, obj}
},
}
endpointInformer := cache.NewSharedIndexInformer(
&cache.ListWatch{
ListFunc: func(opts meta_v1.ListOptions) (runtime.Object, error) {
return client.CoreV1().Endpoints(namespace).List(opts)
},
WatchFunc: func(opts meta_v1.ListOptions) (watch.Interface, error) {
return client.CoreV1().Endpoints(namespace).Watch(opts)
},
},
&v1.Endpoints{}, 1*time.Second, cache.Indexers{},
)
endpointInformer.AddEventHandler(handler)
podInformer := cache.NewSharedIndexInformer(
&cache.ListWatch{
ListFunc: func(opts meta_v1.ListOptions) (runtime.Object, error) {
return client.CoreV1().Pods(namespace).List(opts)
},
WatchFunc: func(opts meta_v1.ListOptions) (watch.Interface, error) {
return client.CoreV1().Pods(namespace).Watch(opts)
},
},
&v1.Pod{}, 1*time.Second, cache.Indexers{},
)
podInformer.AddEventHandler(handler)
stop := make(chan struct{})
go endpointInformer.Run(stop)
go podInformer.Run(stop)
go maintainMirror(eurekaURL, podInformer.GetStore(), events)
c := make(chan os.Signal, 1)
signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
sig := <-c
log.Printf("captured sig %v, exiting\n", sig)
close(stop)
close(events)
os.Exit(1)
}