Fix k8s panic

[emilevauge]

Fixes #877
Fixes #869
DO NOT merge before validation made in #877

[vdemeester]

LGTM 🐯

[jonaz]

Should'nt this be enought? Whats the motives to use "third" party libs in stead of just channels and goroutines directly?

@@ -270,9 +271,9 @@ func (c *clientImpl) watch(url string, labelSelector string, stopCh <-chan bool)
 
        go func() {
                defer close(watchCh)
-               defer close(errCh)
                go func() {
                        defer res.Body.Close()
+                       defer close(errCh)
                        for {
                                var eventList interface{}
                                if err := json.NewDecoder(res.Body).Decode(&eventList); err != nil {

[emilevauge]

@jonaz I don't know what you are calling "third party libs" here.
safe.Go is taken from Traefik directly. The goal is to avoid Traefik to panic and stop. So it is not useless ;)

[jonaz]

I mean some external package thats not part of go. Just thought the fix was a bit to complicated for what was needed. But i'll admit i did not thoroughly read the safe packge from traefik.

[jonaz]

Is'nt there a possible goroutine leak aswell?

	safe.Go(func() {
		EndCh := make(chan bool, 1)
		defer close(watchCh)
		defer close(errCh)
		defer close(EndCh)
		safe.Go(func() {
			defer res.Body.Close()
			defer func() {
				EndCh <- true
			}()
			for {
				var eventList interface{}
				if err := json.NewDecoder(res.Body).Decode(&eventList); err != nil {
					if !strings.Contains(err.Error(), "net/http: request canceled") {
						errCh <- fmt.Errorf("failed to decode watch event: GET %q : %v", url, err)
					}
					return
				}
				watchCh <- eventList
			}
		})
		<-stopCh **// Wont we listen here forever in case of error in Decode?** 
		safe.Go(func() {
			cancel() // cancel watch request
		})
		<-EndCh
	})

provider/kubernetes.go seems to check for error channel and send stop to it. But i dont think a client should be dependant on the usage not to leak goroutines.

DISCLAMER: This maybe should belong in another issue on github.

[emilevauge]

@jonaz goroutine leak has been tested quite intensively during the RC phase.
Besides, we are in the process of moving to the official k8s client in the next release.

[jonaz]

Good. Official client should be sufficient! :D

[errm]

LGTM