💾 ElastiCache Caching

Introduction

AWS ElastiCache provides managed caching to improve application performance and reduce database load.

Key Learning Outcomes

By the end of this lesson, you'll understand:

• Creating cache clusters

• Redis vs Memcached

• Caching patterns

• Invalidation strategies

• Monitoring cache performance

• Cost optimization

Creating a Cache Cluster

# Create Redis cluster
aws elasticache create-cache-cluster \
  --cache-cluster-id my-cache \
  --engine redis \
  --cache-node-type cache.t3.micro \
  --engine-version 7.0 \
  --num-cache-nodes 1

Using Redis

Node.js:

const redis = require('redis');
const client = redis.createClient({
  host: 'my-cache.xxxxx.cache.amazonaws.com',
  port: 6379
});

// Cache data
async function getCachedUser(userId) {
  const cached = await client.get(`user:${userId}`);
  if (cached) return JSON.parse(cached);

  // Fetch from database
  const user = await fetchUserFromDB(userId);
  
  // Store in cache (1 hour TTL)
  await client.setex(`user:${userId}`, 3600, JSON.stringify(user));
  
  return user;
}

Cache Invalidation

// Invalidate on update
async function updateUser(userId, data) {
  // Update database
  await updateUserInDB(userId, data);
  
  // Invalidate cache
  await client.del(`user:${userId}`);
}

Key Takeaways

• **Redis** - in-memory data structure

• **Memcached** - simple key-value cache

• **Session storage** - high speed access

• **Rate limiting** - track usage

• **Reduces latency** and database load

Next Steps

Learn about AWS Monitoring, or explore authentication strategies.