Надежность и доступность — Управление конфигурациями как код

# Terraform — единый источник истины для всех сред
variable "environment" {
  type = string
}

locals {
  # Общие параметры для всех сред
  common_settings = {
    log_level         = "info"
    max_connections   = 100
    request_timeout   = 30
    cache_ttl_seconds = 300
  }
  
  # Специфичные для среды параметры
  environment_settings = {
    dev = {
      instance_count  = 1
      instance_type   = "t3.small"
      log_level       = "debug"
      cache_ttl       = 60
    }
    
    staging = {
      instance_count  = 2
      instance_type   = "t3.medium"
      log_level       = "info"
      cache_ttl       = 300
    }
    
    production = {
      instance_count  = 6
      instance_type   = "t3.large"
      log_level       = "warn"
      cache_ttl       = 600
    }
  }
  
  # Итоговая конфигурация
  final_settings = merge(
    local.common_settings,
    local.environment_settings[var.environment]
  )
}

resource "aws_instance" "app" {
  count         = local.final_settings.instance_count
  instance_type = local.final_settings.instance_type
  
  user_data = templatefile("${path.module}/startup.sh.tpl", {
    log_level    = local.final_settings.log_level
    max_conns    = local.final_settings.max_connections
    cache_ttl    = local.final_settings.cache_ttl
    db_host      = aws_db_instance.app.address
    redis_host   = aws_elasticache_cluster.app.cache_nodes[0].address
  })
}