title: kubernetes filter objects in Informer
body: <p>Im writing custom controller for kubernetes.
  Im creating shared informer</p>
  
  <pre><code>cache.NewSharedIndexInformer(
              &amp;cache.ListWatch{
                  ListFunc: func(options meta_v1.ListOptions) (k8sruntime.Object, error) {
  
                      return client.CoreV1().ConfigMaps(nameSpace).List(options)
                  },
                  WatchFunc: func(options meta_v1.ListOptions) (watch.Interface, error) {
  
                      return client.CoreV1().ConfigMaps(nameSpace).Watch(options)
                  },
              },
              &amp;api_v1.ConfigMap{},
              0, //Skip resyncr
              cache.Indexers{},
          )
  </code></pre>
  
  <p>I have option to add filtering function into call back functions to further decrease number of objects im working with.
  Something like that</p>
  
  <pre><code>options.FieldSelector := fields.OneTermEqualSelector("metadata.name", nodeName).String()
  </code></pre>
  
  <p>I would like to filter out objects by regular expression. Or by some label at least. Unfortunately documentation is not helping. Could not find anything except for tests for code itself.
  Ho do i apply regular expression on filtering mechanism?
  Where do i get some examples on this issue?</p>