Question: How to clear Elasticache?

Answer

ElastiCache is a web service that makes it easy to deploy and run an in-memory cache in the cloud. It supports both Memcached and Redis as caching engines. Clearing an ElastiCache cluster means removing all data stored in it, which can be useful for various reasons such as resetting the cache or removing stale data.

There are different ways to clear an ElastiCache cluster, depending on the caching engine you are using:

Clearing a Memcached Cluster

To clear a Memcached cluster, you can use the flush_all command. This command removes all data from the cluster and resets the statistics. Here's an example of how to use it with Telnet:

telnet [cache-cluster-endpoint] 11211
> flush_all

Replace [cache-cluster-endpoint] with the endpoint of your ElastiCache cluster. You can find the endpoint in the AWS Management Console under the "Details" tab of your cluster.

Alternatively, you can use a Memcached client library to send the flush_all command programmatically. Here's an example using Python and the boto3 library:

import boto3

client = boto3.client('elasticache')
response = client.describe_cache_clusters(CacheClusterId='my-memcached-cluster')

endpoint = response['CacheClusters'][0]['ConfigurationEndpoint']['Address']
port = 11211

import memcache
mc_client = memcache.Client([f'{endpoint}:{port}'])
mc_client.flush_all()

Clearing a Redis Cluster

To clear a Redis cluster, you can use the FLUSHALL command. This command removes all data from the cluster but does not affect the statistics. Here's an example of how to use it with the Redis CLI:

redis-cli -h [cache-cluster-endpoint] FLUSHALL

Replace [cache-cluster-endpoint] with the endpoint of your ElastiCache cluster.

Alternatively, you can use a Redis client library to send the FLUSHALL command programmatically. Here's an example using Python and the redis library:

import boto3

client = boto3.client('elasticache')
response = client.describe_cache_clusters(CacheClusterId='my-redis-cluster')

endpoint = response['CacheClusters'][0]['ConfigurationEndpoint']['Address']
port = 6379

import redis
r_client = redis.Redis(host=endpoint, port=port)
r_client.flushall()

In both cases, please note that clearing an ElastiCache cluster will remove all data stored in it. Therefore, make sure to double-check before running the command, especially in production environments.