Make watch timeout configurable

By default, a watch times out after 30 minutes. For debugging purposes,
it's convenient if this can be decreased. Add an environment variable
CATTLE_WATCH_TIMEOUT_SECONDS to enable setting the timeout in seconds.

pkg/stores/proxy/proxy_store.go

@@ -7,8 +7,10 @@ import (
 	"io"
 	"io/ioutil"
 	"net/http"
+	"os"
 	"reflect"
 	"regexp"
+	"strconv"
 
 	"github.com/pkg/errors"
 	"github.com/rancher/apiserver/pkg/types"
@@ -32,6 +34,8 @@ import (
 	"k8s.io/client-go/kubernetes"
 )
 
+const watchTimeoutEnv = "CATTLE_WATCH_TIMEOUT_SECONDS"
+
 var (
 	lowerChars  = regexp.MustCompile("[a-z]+")
 	paramScheme = runtime.NewScheme()
@@ -291,6 +295,15 @@ func (s *Store) listAndWatch(apiOp *types.APIRequest, client dynamic.ResourceInt
 	}
 
 	timeout := int64(60 * 30)
+	timeoutSetting := os.Getenv(watchTimeoutEnv)
+	if timeoutSetting != "" {
+		userSetTimeout, err := strconv.Atoi(timeoutSetting)
+		if err != nil {
+			logrus.Debugf("could not parse %s environment variable, error: %v", watchTimeoutEnv, err)
+		} else {
+			timeout = int64(userSetTimeout)
+		}
+	}
 	k8sClient, _ := metricsStore.Wrap(client, nil)
 	watcher, err := k8sClient.Watch(apiOp, metav1.ListOptions{
 		Watch:           true,