AWS, Infrastructure as Code

5 min readDec 29, 2019

What is infrastructure as code? Why use it?

Let me give a brief definition, Infrastructure as code is the process of provisioning and managing your cloud resources by writing a template file that is both human-readable, and machine consumable. For AWS cloud development the built-in choice for infrastructure as code is AWS CloudFormation.

Using AWS CloudFormation you can write a description of the resources that you want to create on your AWS account, and then ask AWS CloudFormation to make this description into reality. (source:https://containersonaws.com/introduction/infrastructure-as-code/)

Suppose you have a tech startup and you want AWS as your cloud service provider. For your startup, you need VPC (Amazon VPC enables you to build a virtual network in the AWS cloud — no VPNs, hardware, or physical datacenters required.), S3 bucket, public and private Subnets inside your VPC, Internet Gateway, Application Load Balancer, EC2 Instance, Autoscaling group, NAT Gateway, Routing Table and other resources.

Now you have some options to create and link all those resources needed.

Using the AWS Management Console: Here you have to create and link every resource needed manually. This will take a hell lot of time, and there is a great probability of errors.
Using Cloudformation Template in Management Console: https://aws.amazon.com/cloudformation/getting-started/
Using aws CLI: Here you’ll create the template in that list out all the resources needed and link them to each other. The template should be written in JSON or YAML only. After you create a template, AWS CloudFormation takes this template and then assumes the responsibility of creating, updating, and deleting resources on your AWS account according to what is described in the template. If you add a new resource to the file CloudFormation will create that resource on your account. If you update a resource CloudFormation will either update or replace any existing matching resources. And if you remove a resource from the template it will be cleaned up and removed from your AWS account.

You can create the above-mentioned infrastructure template from this source https://docs.aws.amazon.com/codebuild/latest/userguide/cloudformation-vpc-template.html

Description:  This template deploys a VPC, with a pair of public and private subnets spread
  across two Availability Zones. It deploys an internet gateway, with a default
  route on the public subnets. It deploys a pair of NAT gateways (one in each AZ),
  and default routes for them in the private subnets.Parameters:
  EnvironmentName:
    Description: An environment name that is prefixed to resource names
    Type: StringVpcCIDR:
    Description: Please enter the IP range (CIDR notation) for this VPC
    Type: String
    Default: 10.192.0.0/16PublicSubnet1CIDR:
    Description: Please enter the IP range (CIDR notation) for the public subnet in the first Availability Zone
    Type: String
    Default: 10.192.10.0/24PublicSubnet2CIDR:
    Description: Please enter the IP range (CIDR notation) for the public subnet in the second Availability Zone
    Type: String
    Default: 10.192.11.0/24PrivateSubnet1CIDR:
    Description: Please enter the IP range (CIDR notation) for the private subnet in the first Availability Zone
    Type: String
    Default: 10.192.20.0/24PrivateSubnet2CIDR:
    Description: Please enter the IP range (CIDR notation) for the private subnet in the second Availability Zone
    Type: String
    Default: 10.192.21.0/24Resources:
  VPC:
    Type: AWS::EC2::VPC
    Properties:
      CidrBlock: !Ref VpcCIDR
      EnableDnsSupport: true
      EnableDnsHostnames: true
      Tags:
        - Key: Name
          Value: !Ref EnvironmentNameInternetGateway:
    Type: AWS::EC2::InternetGateway
    Properties:
      Tags:
        - Key: Name
          Value: !Ref EnvironmentNameInternetGatewayAttachment:
    Type: AWS::EC2::VPCGatewayAttachment
    Properties:
      InternetGatewayId: !Ref InternetGateway
      VpcId: !Ref VPCPublicSubnet1:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId: !Ref VPC
      AvailabilityZone: !Select [ 0, !GetAZs '' ]
      CidrBlock: !Ref PublicSubnet1CIDR
      MapPublicIpOnLaunch: true
      Tags:
        - Key: Name
          Value: !Sub ${EnvironmentName} Public Subnet (AZ1)PublicSubnet2:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId: !Ref VPC
      AvailabilityZone: !Select [ 1, !GetAZs  '' ]
      CidrBlock: !Ref PublicSubnet2CIDR
      MapPublicIpOnLaunch: true
      Tags:
        - Key: Name
          Value: !Sub ${EnvironmentName} Public Subnet (AZ2)PrivateSubnet1:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId: !Ref VPC
      AvailabilityZone: !Select [ 0, !GetAZs  '' ]
      CidrBlock: !Ref PrivateSubnet1CIDR
      MapPublicIpOnLaunch: false
      Tags:
        - Key: Name
          Value: !Sub ${EnvironmentName} Private Subnet (AZ1)PrivateSubnet2:
    Type: AWS::EC2::Subnet
    Properties:
      VpcId: !Ref VPC
      AvailabilityZone: !Select [ 1, !GetAZs  '' ]
      CidrBlock: !Ref PrivateSubnet2CIDR
      MapPublicIpOnLaunch: false
      Tags:
        - Key: Name
          Value: !Sub ${EnvironmentName} Private Subnet (AZ2)NatGateway1EIP:
    Type: AWS::EC2::EIP
    DependsOn: InternetGatewayAttachment
    Properties:
      Domain: vpcNatGateway2EIP:
    Type: AWS::EC2::EIP
    DependsOn: InternetGatewayAttachment
    Properties:
      Domain: vpcNatGateway1:
    Type: AWS::EC2::NatGateway
    Properties:
      AllocationId: !GetAtt NatGateway1EIP.AllocationId
      SubnetId: !Ref PublicSubnet1NatGateway2:
    Type: AWS::EC2::NatGateway
    Properties:
      AllocationId: !GetAtt NatGateway2EIP.AllocationId
      SubnetId: !Ref PublicSubnet2PublicRouteTable:
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId: !Ref VPC
      Tags:
        - Key: Name
          Value: !Sub ${EnvironmentName} Public RoutesDefaultPublicRoute:
    Type: AWS::EC2::Route
    DependsOn: InternetGatewayAttachment
    Properties:
      RouteTableId: !Ref PublicRouteTable
      DestinationCidrBlock: 0.0.0.0/0
      GatewayId: !Ref InternetGatewayPublicSubnet1RouteTableAssociation:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      RouteTableId: !Ref PublicRouteTable
      SubnetId: !Ref PublicSubnet1PublicSubnet2RouteTableAssociation:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      RouteTableId: !Ref PublicRouteTable
      SubnetId: !Ref PublicSubnet2PrivateRouteTable1:
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId: !Ref VPC
      Tags:
        - Key: Name
          Value: !Sub ${EnvironmentName} Private Routes (AZ1)DefaultPrivateRoute1:
    Type: AWS::EC2::Route
    Properties:
      RouteTableId: !Ref PrivateRouteTable1
      DestinationCidrBlock: 0.0.0.0/0
      NatGatewayId: !Ref NatGateway1PrivateSubnet1RouteTableAssociation:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      RouteTableId: !Ref PrivateRouteTable1
      SubnetId: !Ref PrivateSubnet1PrivateRouteTable2:
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId: !Ref VPC
      Tags:
        - Key: Name
          Value: !Sub ${EnvironmentName} Private Routes (AZ2)DefaultPrivateRoute2:
    Type: AWS::EC2::Route
    Properties:
      RouteTableId: !Ref PrivateRouteTable2
      DestinationCidrBlock: 0.0.0.0/0
      NatGatewayId: !Ref NatGateway2PrivateSubnet2RouteTableAssociation:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      RouteTableId: !Ref PrivateRouteTable2
      SubnetId: !Ref PrivateSubnet2

To run the above template from your terminal you need an aws CLI tool installed on your terminal and can run this bash script. A helpful source for https://gist.github.com/mdjnewman/b9d722188f4f9c6bb277a37619665e77

Benefits of infrastructure as code

Infrastructure as code brings a lot of benefits:

Visibility: An infrastructure as code template serves as a very clear reference of what resources are on your account, and what their settings are. You don’t have to navigate to the web console to check the parameters.
Stability: If you accidentally change the wrong setting or delete the wrong resource in the web console you can break things. Infrastructure as code helps solve this, especially when it is combined with version control, such as Git.
Scalability: With infrastructure as code you can write it once and then reuse it many times. This means that one well-written template can be used as the basis for multiple services, in multiple regions around the world, making it much easier to horizontally scale.
Security: Once again infrastructure as code gives you a unified template for how to deploy your architecture. If you create one well-secured architecture you can reuse it multiple times, and know that each deployed version is following the same settings.
Transactional: CloudFormation not only creates resources on your AWS account but also waits for them to stabilize while they start. It verifies that provisioning was successful, and if there is a failure it can gracefully roll the infrastructure back to a last known good state.

Thank you for reading! Let me know in a comment if you felt like this did or didn’t help. I’ve got a few more cloud-related articles that I’m writing and will be posting them very soon. If there are any other questions or anything else you’d like to hear about, please don’t hesitate to put in a request.

AWS, Infrastructure as Code

Benefits of infrastructure as code

Written by Shubham Singh

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