Ignore rkt network failure if container died early

If the container dies before the network can be read, we now ignore the
error coming out of the network information polling loop. Nomad will
restart the task regardless, so we might be masking the actual error.

The polling loop for the rkt network information, inside the `Start`
method, was getting a bit unwieldy. It's been refactored out so it's not
a seperate function.

client/driver/rkt.go

@@ -156,6 +156,50 @@ func rktGetManifest(uuid string) (*appcschema.PodManifest, error) {
 	return &manifest, nil
 }
 
+func rktGetDriverNetwork(uuid string, driverConfigPortMap map[string]string) (*cstructs.DriverNetwork, error) {
+	deadline := time.Now().Add(rktNetworkDeadline)
+	var lastErr error
+	for time.Now().Before(deadline) {
+		if status, err := rktGetStatus(uuid); err == nil {
+			for _, net := range status.Networks {
+				if !net.IP.IsGlobalUnicast() {
+					continue
+				}
+
+				// Get the pod manifest so we can figure out which ports are exposed
+				var portmap map[string]int
+				manifest, err := rktGetManifest(uuid)
+				if err == nil {
+					portmap, err = rktManifestMakePortMap(manifest, driverConfigPortMap)
+					if err != nil {
+						lastErr = fmt.Errorf("could not create manifest-based portmap: %v", err)
+						return nil, lastErr
+					}
+				} else {
+					lastErr = fmt.Errorf("could not get pod manifest: %v", err)
+					return nil, lastErr
+				}
+
+				return &cstructs.DriverNetwork{
+					PortMap: portmap,
+					IP:      status.Networks[0].IP.String(),
+				}, nil
+			}
+
+			if len(status.Networks) == 0 {
+				lastErr = fmt.Errorf("no networks found")
+			} else {
+				lastErr = fmt.Errorf("no good driver networks out of %d returned", len(status.Networks))
+			}
+		} else {
+			lastErr = fmt.Errorf("getting status failed: %v", err)
+		}
+
+		time.Sleep(400 * time.Millisecond)
+	}
+	return nil, fmt.Errorf("timed out, last error: %v", lastErr)
+}
+
 // Given a rkt/appc pod manifest and driver portmap configuration, create
 // a driver portmap.
 func rktManifestMakePortMap(manifest *appcschema.PodManifest, configPortMap map[string]string) (map[string]int, error) {
@@ -590,56 +634,11 @@ func (d *RktDriver) Start(ctx *ExecContext, task *structs.Task) (*StartResponse,
 	}
 	go h.run()
 
-	d.logger.Printf("[DEBUG] driver.rkt: retrieving status for pod %q (UUID %s) for task %q", img, uuid, d.taskName)
+	d.logger.Printf("[DEBUG] driver.rkt: retrieving network information for pod %q (UUID %s) for task %q", img, uuid, d.taskName)
-	deadline := time.Now().Add(rktNetworkDeadline)
+	driverNetwork, err := rktGetDriverNetwork(uuid, driverConfig.PortMap)
-	var driverNetwork *cstructs.DriverNetwork
+	if err != nil && !pluginClient.Exited() {
-	var lastErr error
+		d.logger.Printf("[WARN] driver.rkt: network status retrieval for pod %q (UUID %s) for task %q failed. Last error: %v", img, uuid, d.taskName, err)
-networkLoop:
-	for driverNetwork == nil && time.Now().Before(deadline) {
-		if status, err := rktGetStatus(uuid); err == nil {
-			for _, net := range status.Networks {
-				if !net.IP.IsGlobalUnicast() {
-					d.logger.Printf("[DEBUG] driver.rkt: network %s for pod %q (UUID %s) for task %q ignored", net.IP.String(), img, uuid, d.taskName)
-					continue
-				}
 
-				// Get the pod manifest so we can figure out which ports are exposed
-				var portmap map[string]int
-				d.logger.Printf("[DEBUG] driver.rkt: grabbing manifest for pod %q (UUID %s) for task %q", img, uuid, d.taskName)
-				manifest, err := rktGetManifest(uuid)
-				if err == nil {
-					portmap, err = rktManifestMakePortMap(manifest, driverConfig.PortMap)
-					if err != nil {
-						lastErr = err
-						d.logger.Printf("[WARN] driver.rkt: could not create manifest-based portmap for %q (UUID %s) for task %q: %v", img, uuid, d.taskName, err)
-						break networkLoop
-					}
-				} else {
-					lastErr = err
-					d.logger.Printf("[WARN] driver.rkt: could get not pod manifest for %q (UUID %s) for task %q: %v", img, uuid, d.taskName, err)
-					break networkLoop
-				}
-
-				driverNetwork = &cstructs.DriverNetwork{
-					PortMap: portmap,
-					IP:      status.Networks[0].IP.String(),
-				}
-				break networkLoop
-			}
-
-			if len(status.Networks) == 0 {
-				lastErr = fmt.Errorf("no networks found")
-			} else {
-				lastErr = fmt.Errorf("no good driver networks out of %d returned", len(status.Networks))
-			}
-		} else {
-			lastErr = err
-		}
-
-		time.Sleep(400 * time.Millisecond)
-	}
-	if driverNetwork == nil {
-		d.logger.Printf("[WARN] driver.rkt: network status retrieval for pod %q (UUID %s) for task %q failed. Last error: %v", img, uuid, d.taskName, lastErr)
 		// If a portmap was given, this turns into a fatal error
 		if len(driverConfig.PortMap) != 0 {
 			pluginClient.Kill()