micro/registry/kubernetes/watcher.go

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package kubernetes
import (
"encoding/json"
"errors"
"strings"
"sync"
"github.com/micro/go-micro/registry"
"github.com/micro/go-micro/util/kubernetes/client"
"github.com/micro/go-micro/util/log"
)
type k8sWatcher struct {
registry *kregistry
watcher client.Watcher
next chan *registry.Result
stop chan bool
sync.RWMutex
pods map[string]*client.Pod
}
// build a cache of pods when the watcher starts.
func (k *k8sWatcher) updateCache() ([]*registry.Result, error) {
var pods client.PodList
if err := k.registry.client.Get(&client.Resource{
Kind: "pod",
Value: &pods,
}, podSelector); err != nil {
return nil, err
}
var results []*registry.Result
for _, pod := range pods.Items {
rslts := k.buildPodResults(&pod, nil)
for _, r := range rslts {
results = append(results, r)
}
k.Lock()
k.pods[pod.Metadata.Name] = &pod
k.Unlock()
}
return results, nil
}
// look through pod annotations, compare against cache if present
// and return a list of results to send down the wire.
func (k *k8sWatcher) buildPodResults(pod *client.Pod, cache *client.Pod) []*registry.Result {
var results []*registry.Result
ignore := make(map[string]bool)
if pod.Metadata != nil {
for ak, av := range pod.Metadata.Annotations {
// check this annotation kv is a service notation
if !strings.HasPrefix(ak, annotationPrefix) {
continue
}
if len(av) == 0 {
continue
}
// ignore when we check the cached annotations
// as we take care of it here
ignore[ak] = true
// compare aginst cache.
var cacheExists bool
var cav string
if cache != nil && cache.Metadata != nil {
cav, cacheExists = cache.Metadata.Annotations[ak]
if cacheExists && len(cav) > 0 && cav == av {
// service notation exists and is identical -
// no change result required.
continue
}
}
rslt := &registry.Result{}
if cacheExists {
rslt.Action = "update"
} else {
rslt.Action = "create"
}
// unmarshal service notation from annotation value
err := json.Unmarshal([]byte(av), &rslt.Service)
if err != nil {
continue
}
results = append(results, rslt)
}
}
// loop through cache annotations to find services
// not accounted for above, and "delete" them.
if cache != nil && cache.Metadata != nil {
for ak, av := range cache.Metadata.Annotations {
if ignore[ak] {
continue
}
// check this annotation kv is a service notation
if !strings.HasPrefix(ak, annotationPrefix) {
continue
}
rslt := &registry.Result{Action: "delete"}
// unmarshal service notation from annotation value
err := json.Unmarshal([]byte(av), &rslt.Service)
if err != nil {
continue
}
results = append(results, rslt)
}
}
return results
}
// handleEvent will taken an event from the k8s pods API and do the correct
// things with the result, based on the local cache.
func (k *k8sWatcher) handleEvent(event client.Event) {
var pod client.Pod
if err := json.Unmarshal([]byte(event.Object), &pod); err != nil {
log.Log("K8s Watcher: Couldnt unmarshal event object from pod")
return
}
switch event.Type {
case client.Modified:
// Pod was modified
k.RLock()
cache := k.pods[pod.Metadata.Name]
k.RUnlock()
// service could have been added, edited or removed.
var results []*registry.Result
if pod.Status.Phase == podRunning {
results = k.buildPodResults(&pod, cache)
} else {
// passing in cache might not return all results
results = k.buildPodResults(&pod, nil)
}
for _, result := range results {
// pod isnt running
if pod.Status.Phase != podRunning {
result.Action = "delete"
}
select {
case k.next <- result:
case <-k.stop:
return
}
}
k.Lock()
k.pods[pod.Metadata.Name] = &pod
k.Unlock()
return
case client.Deleted:
// Pod was deleted
// passing in cache might not return all results
results := k.buildPodResults(&pod, nil)
for _, result := range results {
result.Action = "delete"
select {
case k.next <- result:
case <-k.stop:
return
}
}
k.Lock()
delete(k.pods, pod.Metadata.Name)
k.Unlock()
return
}
}
// Next will block until a new result comes in
func (k *k8sWatcher) Next() (*registry.Result, error) {
select {
case r := <-k.next:
return r, nil
case <-k.stop:
return nil, errors.New("watcher stopped")
}
}
// Stop will cancel any requests, and close channels
func (k *k8sWatcher) Stop() {
select {
case <-k.stop:
return
default:
k.watcher.Stop()
close(k.stop)
}
}
func newWatcher(kr *kregistry, opts ...registry.WatchOption) (registry.Watcher, error) {
var wo registry.WatchOptions
for _, o := range opts {
o(&wo)
}
selector := podSelector
if len(wo.Service) > 0 {
selector = map[string]string{
servicePrefix + serviceName(wo.Service): serviceValue,
}
}
// Create watch request
watcher, err := kr.client.Watch(&client.Resource{
Kind: "pod",
}, client.WatchParams(selector))
if err != nil {
return nil, err
}
k := &k8sWatcher{
registry: kr,
watcher: watcher,
next: make(chan *registry.Result),
stop: make(chan bool),
pods: make(map[string]*client.Pod),
}
// update cache, but dont emit changes
if _, err := k.updateCache(); err != nil {
return nil, err
}
// range over watch request changes, and invoke
// the update event
go func() {
for event := range watcher.Chan() {
k.handleEvent(event)
}
}()
return k, nil
}