Scaling & Performance

# ElastiCache Redis reduces DB load by 80%
aws elasticache create-cache-cluster \
  --cache-cluster-id govtech-redis-prod \
  --cache-node-type cache.r5.large \
  --engine redis \
  --num-cache-nodes 2

resource "aws_cloudfront_distribution" "main" {
  origin {
    domain_name = aws_lb.main.dns_name
    origin_id   = "ALB"
  }
  
  # Cache static assets
  default_cache_behavior {
    allowed_methods  = ["GET", "HEAD", "OPTIONS"]
    cached_methods   = ["GET", "HEAD"]
    target_origin_id = "ALB"
    
    min_ttl     = 0
    default_ttl = 300   # 5 minutes
    max_ttl     = 3600  # 1 hour
  }
}

CloudFront CDN (Edge Locations)
       ↓ (70% of requests cached)

ALB (Dynamic traffic only)
       ↓

EKS Cluster (2-20 pods via HPA)
  ├── Backend 1
  ├── Backend 2
  ├── Backend N
  └── Redis Cache (80% hit rate)
           ↓ (20% miss → DB)

RDS Primary (Writes)    RDS Replica 1 (Reads)    RDS Replica 2 (Reads)
     20% queries             40% reads                40% reads

-- Shard by Department (Colombian example)
Shard 1: Antioquia (6.5M people)
  → rds-antioquia.us-east-1.rds.amazonaws.com

Shard 2: Bogotá D.C. (8M people)
  → rds-bogota.us-east-1.rds.amazonaws.com

Shard 3: Valle del Cauca (4.6M people)
  → rds-valle.us-east-1.rds.amazonaws.com

Shard N: Other regions
  → rds-other.us-east-1.rds.amazonaws.com

Primary Region: us-east-1 (Virginia) → 60% traffic
Secondary Region: sa-east-1 (São Paulo) → 40% traffic

Route 53 Geolocation Routing:
  → North America citizens → us-east-1
  → South America citizens → sa-east-1

resource "aws_rds_cluster" "primary" {
  region = "us-east-1"
  engine = "aurora-postgresql"
  
  # Enable global database
  global_cluster_identifier = "govtech-global"
}

resource "aws_rds_cluster" "secondary" {
  region = "sa-east-1"
  engine = "aurora-postgresql"
  
  # Replicate from primary
  global_cluster_identifier = "govtech-global"
  source_region             = "us-east-1"
}

resource "aws_elasticache_replication_group" "redis" {
  replication_group_id       = "govtech-redis-cluster"
  replication_group_description = "Redis cluster for GovTech"
  engine                     = "redis"
  node_type                  = "cache.r5.xlarge"
  
  # Cluster mode enabled (sharded)
  num_node_groups         = 3  # 3 shards
  replicas_per_node_group = 2  # 2 replicas per shard
  
  automatic_failover_enabled = true
  multi_az_enabled          = true
}