controllerkuberneteskube-controller-manager

In Kubernetes controller what's the preferred way to get an item from the informer cache?

I am looking at following 2 examples, in the first example A lister is used to retrieve the item.

In the second example , an index is used.

I am wondering which is the preferred way and way to retrieve an element from the local cache.

Solution

  • The examples you showed above, they both use indexer, if you go deeper you will see it.

    For First example (see here)

    // Get retrieves the Node from the index for a given name.
func (s *nodeLister) Get(name string) (*v1.Node, error) {
    obj, exists, err := s.indexer.GetByKey(name)
    if err != nil {
        return nil, err
    }
    if !exists {
        return nil, errors.NewNotFound(v1.Resource("node"), name)
    }
    return obj.(*v1.Node), nil
}

    For second example

    item, exists, err := c.informer.GetIndexer().GetByKey(keyRaw)