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VPC and Subnet Configuration Overrides ​

Overview ​

This guide will help you configure VPC and subnet overrides for your environment. The configuration allows you to customize network settings including CIDR blocks, availability zones, and subnet configurations.

Network Architecture ​

The configuration supports the following subnet types:

  • Public Subnets [ publicSubnet1, publicSubnet2 ]
  • Private Subnets [privateSubnet1, privateSubnet2]
  • Private Isolated Subnets [privateIsolatedSubnet1, privateIsolatedSubnet2 ]

Configuration Example ​

Below is a sample VPC and subnet configuration exported from a running LISA deployment. You can use this as a template for your overrides:

json

{
  "Description": "LISA-networking: app-dev",
  "Resources": {
    "Vpc": {
      "Type": "AWS::EC2::VPC",
      "Properties": {
        "CidrBlock": "10.0.0.0/22",
        "EnableDnsHostnames": true,
        "EnableDnsSupport": true
      },
      "publicSubnet1": {
        "Type": "AWS::EC2::Subnet",
        "Properties": {
          "AvailabilityZone": "us-west-2a",
          "CidrBlock": "10.0.0.0/26",
          "MapPublicIpOnLaunch": true
        }
      },
      "publicSubnet2": {
        "Type": "AWS::EC2::Subnet",
        "Properties": {
          "AvailabilityZone": "us-west-2b",
          "CidrBlock": "10.0.0.64/26",
          "MapPublicIpOnLaunch": true,
          "VpcId": {
            "Ref": "VpcVPC8B8C4E4B"
          }
        }
      },
      "VpcVPCprivateIsolatedSubnet1Subnet595DCC9B": {
        "Type": "AWS::EC2::Subnet",
        "Properties": {
          "AvailabilityZone": "us-west-2a",
          "CidrBlock": "10.0.0.128/26",
          "MapPublicIpOnLaunch": false,
          "VpcId": {
            "Ref": "VpcVPC8B8C4E4B"
          }
        }
      },
      "VpcVPCprivateIsolatedSubnet2SubnetFD505B6C": {
        "Type": "AWS::EC2::Subnet",
        "Properties": {
          "AvailabilityZone": "us-west-2b",
          "CidrBlock": "10.0.0.192/26",
          "MapPublicIpOnLaunch": false,
          "VpcId": {
            "Ref": "VpcVPC8B8C4E4B"
          }
        }
      },
      "VpcVPCprivateSubnet1Subnet29B9FADC": {
        "Type": "AWS::EC2::Subnet",
        "Properties": {
          "AvailabilityZone": "us-west-2a",
          "CidrBlock": "10.0.1.0/26",
          "MapPublicIpOnLaunch": false,
          "VpcId": {
            "Ref": "VpcVPC8B8C4E4B"
          }
        }
      },
      "VpcVPCprivateSubnet2Subnet63498DC1": {
        "Type": "AWS::EC2::Subnet",
        "Properties": {
          "AvailabilityZone": "us-west-2b",
          "CidrBlock": "10.0.1.64/26",
          "MapPublicIpOnLaunch": false,
          "VpcId": {
            "Ref": "VpcVPC8B8C4E4B"
          }
        }
      }
    }
  }
}

Required Properties ​

For each subnet, you must specify:

  • AvailabilityZone
  • CidrBlock
  • VpcId
  • MapPublicIpOnLaunch (true for public subnets, false for private)

Best Practices ​

  1. Distribute subnets across different Availability Zones for high availability

  2. Ensure CIDR blocks don't overlap between subnets

  3. Plan IP address space according to your workload requirements

  4. Enable DNS support and hostnames in the VPC

VPC (10.0.0.0/22)
├── Public Subnet 1    (10.0.0.0/26)   - AZ a
├── Public Subnet 2    (10.0.0.64/26)  - AZ b
├── Private Subnet 1   (10.0.0.128/26) - AZ a
├── Private Subnet 2   (10.0.0.192/26) - AZ b
├── Isolated Subnet 1  (10.0.1.0/26)   - AZ a
└── Isolated Subnet 2  (10.0.1.64/26)  - AZ b