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# Terraform configuration for AWS App Mesh with Virtual Gateway and Services
# This example demonstrates a production-ready e-commerce microservices setup

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

provider "aws" {
  region = var.aws_region
}

# Create App Mesh
resource "aws_appmesh_mesh" "ecommerce_mesh" {
  name = "ecommerce-mesh"

  spec {
    egress_filter {
      type = "ALLOW_ALL"
    }
  }

  tags = {
    Environment = "production"
    Application = "ecommerce"
  }
}

# Virtual Gateway for ingress traffic
resource "aws_appmesh_virtual_gateway" "api_gateway" {
  name      = "api-gateway"
  mesh_name = aws_appmesh_mesh.ecommerce_mesh.id

  spec {
    listener {
      port_mapping {
        port     = 443
        protocol = "http"
      }

      health_check {
        healthy_threshold   = 2
        interval_millis     = 5000
        protocol            = "http"
        timeout_millis      = 2000
        unhealthy_threshold = 2
        path                = "/health"
      }

      tls {
        mode = "STRICT"
        certificate {
          acm {
            certificate_arn = var.acm_certificate_arn
          }
        }
      }
    }

    logging {
      access_log {
        file {
          path = "/dev/stdout"
        }
      }
    }
  }
}

# Virtual Service for Product API
resource "aws_appmesh_virtual_service" "product_service" {
  name      = "product-service.ecommerce.local"
  mesh_name = aws_appmesh_mesh.ecommerce_mesh.id

  spec {
    provider {
      virtual_router {
        virtual_router_name = aws_appmesh_virtual_router.product_router.name
      }
    }
  }
}

# Virtual Router with weighted routing for canary deployments
resource "aws_appmesh_virtual_router" "product_router" {
  name      = "product-router"
  mesh_name = aws_appmesh_mesh.ecommerce_mesh.id

  spec {
    listener {
      port_mapping {
        port     = 8080
        protocol = "http"
      }
    }
  }
}

# Route with canary deployment (90% stable, 10% canary)
resource "aws_appmesh_route" "product_route" {
  name                = "product-route"
  mesh_name           = aws_appmesh_mesh.ecommerce_mesh.id
  virtual_router_name = aws_appmesh_virtual_router.product_router.name

  spec {
    http_route {
      match {
        prefix = "/"
      }

      retry_policy {
        http_retry_events = [
          "server-error",
          "gateway-error"
        ]
        max_retries = 3
        per_retry_timeout {
          unit  = "s"
          value = 2
        }
      }

      timeout {
        idle {
          unit  = "s"
          value = 60
        }
        per_request {
          unit  = "s"
          value = 10
        }
      }

      action {
        weighted_target {
          virtual_node = aws_appmesh_virtual_node.product_v1.name
          weight       = 90
        }
        weighted_target {
          virtual_node = aws_appmesh_virtual_node.product_v2_canary.name
          weight       = 10
        }
      }
    }
  }
}

# Virtual Node for stable version
resource "aws_appmesh_virtual_node" "product_v1" {
  name      = "product-v1-node"
  mesh_name = aws_appmesh_mesh.ecommerce_mesh.id

  spec {
    listener {
      port_mapping {
        port     = 8080
        protocol = "http"
      }

      health_check {
        protocol            = "http"
        path                = "/health"
        healthy_threshold   = 2
        unhealthy_threshold = 3
        timeout_millis      = 2000
        interval_millis     = 5000
      }

      outlier_detection {
        max_ejection_percent = 50
        max_server_errors    = 5
        interval {
          unit  = "s"
          value = 10
        }
        base_ejection_duration {
          unit  = "s"
          value = 30
        }
      }
    }

    service_discovery {
      aws_cloud_map {
        service_name   = "product-v1"
        namespace_name = var.cloud_map_namespace
      }
    }

    backend {
      virtual_service {
        virtual_service_name = aws_appmesh_virtual_service.database_service.name
      }
    }

    logging {
      access_log {
        file {
          path = "/dev/stdout"
        }
      }
    }
  }
}

# Virtual Node for canary version
resource "aws_appmesh_virtual_node" "product_v2_canary" {
  name      = "product-v2-canary-node"
  mesh_name = aws_appmesh_mesh.ecommerce_mesh.id

  spec {
    listener {
      port_mapping {
        port     = 8080
        protocol = "http"
      }

      health_check {
        protocol            = "http"
        path                = "/health"
        healthy_threshold   = 2
        unhealthy_threshold = 3
        timeout_millis      = 2000
        interval_millis     = 5000
      }

      outlier_detection {
        max_ejection_percent = 50
        max_server_errors    = 5
        interval {
          unit  = "s"
          value = 10
        }
        base_ejection_duration {
          unit  = "s"
          value = 30
        }
      }
    }

    service_discovery {
      aws_cloud_map {
        service_name   = "product-v2"
        namespace_name = var.cloud_map_namespace
      }
    }

    backend {
      virtual_service {
        virtual_service_name = aws_appmesh_virtual_service.database_service.name
      }
    }

    logging {
      access_log {
        file {
          path = "/dev/stdout"
        }
      }
    }
  }
}

# Database Virtual Service (backend dependency)
resource "aws_appmesh_virtual_service" "database_service" {
  name      = "database-service.ecommerce.local"
  mesh_name = aws_appmesh_mesh.ecommerce_mesh.id

  spec {
    provider {
      virtual_node {
        virtual_node_name = aws_appmesh_virtual_node.database_node.name
      }
    }
  }
}

resource "aws_appmesh_virtual_node" "database_node" {
  name      = "database-node"
  mesh_name = aws_appmesh_mesh.ecommerce_mesh.id

  spec {
    listener {
      port_mapping {
        port     = 5432
        protocol = "tcp"
      }

      connection_pool {
        tcp {
          max_connections = 100
        }
      }
    }

    service_discovery {
      dns {
        hostname = var.rds_endpoint
      }
    }
  }
}

# Gateway Route to route external traffic to product service
resource "aws_appmesh_gateway_route" "product_gateway_route" {
  name                 = "product-gateway-route"
  mesh_name            = aws_appmesh_mesh.ecommerce_mesh.id
  virtual_gateway_name = aws_appmesh_virtual_gateway.api_gateway.name

  spec {
    http_route {
      match {
        prefix = "/api/products"
      }

      action {
        target {
          virtual_service {
            virtual_service_name = aws_appmesh_virtual_service.product_service.name
          }
        }
      }
    }
  }
}

variable "aws_region" {
  description = "AWS region"
  type        = string
  default     = "us-east-1"
}

variable "acm_certificate_arn" {
  description = "ACM certificate ARN for TLS"
  type        = string
}

variable "cloud_map_namespace" {
  description = "AWS Cloud Map namespace"
  type        = string
}

variable "rds_endpoint" {
  description = "RDS database endpoint"
  type        = string
}

output "mesh_id" {
  value = aws_appmesh_mesh.ecommerce_mesh.id
}

output "virtual_gateway_arn" {
  value = aws_appmesh_virtual_gateway.api_gateway.arn
}