Note_Tech

All technological notes.

---

Project maintained by simonangel-fong Hosted on GitHub Pages — Theme by mattgraham

AWS - ElastiCache

Back

• AWS - ElastiCache
  • Amazon ElastiCache
    • Solution Architecture
    • Redis vs Memcached
    • Hands-on
  • Cache Security
  • Patterns for ElastiCache
  • Redis Use Case

---

Amazon ElastiCache

• The same way RDS is to get managed Relational Databases…
• ElastiCache is to get managed Redis or Memcached
• Caches are in-memory databases with really high performance, low latency
• Helps reduce load off of databases for read intensive workloads
• Helps make your application stateless
• AWS takes care of OS maintenance / patching, optimizations, setup, configuration, monitoring, failure recovery and backups
• Using ElastiCache involves heavy application code changes

---

Solution Architecture

• DB Cache
  • Applications queries ElastiCache, if not available, get from RDS and store in ElastiCache.
  • Helps relieve load in RDS
  • Cache must have an invalidation strategy to make sure only the most current data is used in there.

• User Session Store

  • User logs into any of the application
  • The application writes the session data into ElastiCache
  • The user hits another instance of our application
  • The instance retrieves the data and the user is already logged in

---

Redis vs Memcached

---

Hands-on

---

Cache Security

• ElastiCache supports IAM Authentication for Redis

• IAM policies on ElastiCache are only used for AWS API-level security

• Redis AUTH

  • You can set a “password/token” when you create a Redis cluster
  • This is an extra level of security for your cache (on top of security groups)
  • Support SSL in flight encryption

• Memcached
  • Supports SASL-based authentication (advanced)

---

Patterns for ElastiCache

• Lazy Loading:

  • all the read data is cached, data can become stale in cache
• Write Through:
  • Adds or update data in the cache when written to a DB (no stale data)
• Session Store:
  • store temporary session data in a cache (using TTL features)
  • Storing Session Data in ElastiCache is a common pattern to ensuring different EC2 instances can retrieve your user’s state if needed.
• Quote:
  • There are only two hard things in Computer Science: cache invalidation and naming things

---

Redis Use Case

• Gaming Leaderboards are computationally complex.
• Redis Sorted sets guarantee both uniqueness and element ordering.
• Each time a new element added, it’s ranked in real time, then added in correct order.

---

Top