make sure the instance is actually running

- for example, in terminated state

Docker-DCO-1.1-Signed-off-by: Aaron Feng aaron.feng@gmail.com (github: aaronfeng)

backends/ec2.go

@@ -175,7 +175,14 @@ func (c *ec2Client) findInstance() (instance *ec2.Instance, err error) {
     if resp.Reservations == nil {
       return nil, nil
     }
-    return &resp.Reservations[0].Instances[0], nil
+
+    instance := resp.Reservations[0].Instances[0]
+
+    if (instance.State.Name != "running" || instance.State.Name != "pending") {
+      return nil, nil
+    }
+
+    return &instance, nil
   }
 }