Amazon ElastiCache is a fully-managed, in-memory data store service. It helps to improve the performance of web applications by allowing them to retrieve information from fast and managed in-memory caches, instead of relying entirely on slower disk-based databases. Amazon ElastiCache supports two open-source in-memory caching engines - Redis and Memcached.
An ElastiCache cluster is a grouping of one or more cache nodes. The nodes are used to store cached data, which can be a primary replica or both. It allows you to replicate cached data for durability, high availability, and low latency access to data.
You can create an ElastiCache cluster from the AWS Management Console, AWS CLI, or through SDKs. After creating the cluster, applications can connect to the cluster using endpoints specified during the creation of the cluster.
Here's an example of how to create an ElastiCache cluster using the AWS CLI:
aws elasticache create-cache-cluster --cache-cluster-id my-cluster --engine memcached --cache-node-type cache.m3.medium --num-cache-nodes 2 --preferred-availability-zone us-west-1a
This command creates a new ElastiCache cluster with the ID "my-cluster", using the memcached engine, two cache nodes of type
cache.m3.medium, and set to be deployed in the preferred availability zone
In conclusion, an ElastiCache cluster is a group of cache nodes that work together as a unit to provide in-memory cache service. It helps to improve the performance of web applications and provides high availability and scalability to the cached data.