ElasticCache - What is the difference between the configuration and node endpoint?

Question

ElasticCache gives you both a configuration end point, and an individual node endpoint.

What is really the difference between the two? And a use case that you'd use one versus the other?

I assume configuration end point could point to a group of node endpoints, but I don't really quite get it. A use case example would really help me understand when you'd want to use the 2 differently.

Answer 1

My understanding of the AWS docs on this topic is that the configuration endpoint is what you need if you have multiple nodes. It looks like you would plug the configuration endpoint URL into their cache client software which download from your elasticache AWS management console (looks only available in Java and PHP at the moment).

If you just have one node then the node endpoint is the one you use with memcache, which with PHP looks like this:

$memcache = memcache_connect('yourECname.tvgtaa.0001.use1.cache.amazonaws.com', 11211);

http://www.php.net/manual/en/memcache.connect.php

p.s. once you download the the cache client, within it it has a link for installation directions which seem pretty self-explanatory: http://docs.aws.amazon.com/AmazonElastiCache/latest/UserGuide/Appendix.PHPAutoDiscoverySetup.html

Answer 2

As per my understanding, Node endpoint is associated to particular node which is present in cluster, and Configuration endpoint is for cluster management. Each Node endpoint is connected to Configuration endpoint to get details about other nodes present in that cluster.

The configuration endpoint DNS entry contains the CNAME entries for each of the cache node endpoints; thus, by connecting to the configuration endpoint, you application immediately knows about all of the nodes in the cluster and can connect to all of them.You do not need to hard code the individual cache node endpoints in your application.

For more information on Auto Discovery, see Node Auto Discovery (Memcached).