AWS Tutorial: Create VPC and Launch Instance Using CLI

In this tutorial, i will describe the steps required to create a VPC using AWS CLI.

Prerequisites

1. You need to have a configured AWS CLI on your system. (Refer this tutorial: Configure AWS CLI)

Create VPC using CLI

The first step in creating VPC is deciding on the CIDR range. The maximum CIDR range you can have on AWS is /16 network. In this tutorial, i am going to create a VPC with CIDR range 10.0.0.0/16. Please note down all the id’s created in a notepad when you are executing the command.

step 1: Create VPC

To create VPC, we have an AWS CLI command.create-vpc Execute the following command to create a VPC with 10.0.0.0/16 range.

aws ec2 create-vpc --cidr-block 10.0.0.0/16

The above command will give an out with a parameter named.VpcId Note down the Id because we would need it for further commands.

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Step 2: Create Subnets

Next, we need to create subnets for the VPC we created. Subnets basically give you a segregation for your application. Let’s say you have a front end, app tier, and Db tier. You might need 6 subnets to host that application in high availability mode.

For this demo, I will create two subnets, one private and one public.

Execute the following command to create a subnet using create-subnet command

Note: Replace the VPC Id with yours.

aws ec2 create-subnet --vpc-id vpc-99e344fd --cidr-block 10.0.1.0/24

Create the second subnet using the following command.

aws ec2 create-subnet --vpc-id vpc-99e344fd --cidr-block 10.0.2.0/24

Note down the subnet id from the output. We will need it later.

Step 3: Create Internet gateway

If you want to access ec2 instances over the internet, you should attach an internet gateway to your VPC.

You can create an internet gateway using create-internet-gateway command. Execute the following command to create one.

aws ec2 create-internet-gateway

Note down the InternetGatewayId from the output.

Step 4: Attach Internet gateway to VPC

Attach the internet gateway to the VPC using ec2 attach-internet-gateway command as shown below. Replace the id’s with your id’s accordingly.

aws ec2 attach-internet-gateway --internet-gateway-id igw-5d685a38 --vpc-id vpc-99e344fd

Step 5: Create Route Table

First, create a route table. Replace the VPC id with yours.

aws ec2 create-route-table --vpc-id vpc-99e344fd

Note down the RouteTableId

Step 6: Add Internet Gateway Rule

Attaching internet gateway does not make all the subnets public. If you want to make a subnet public, you need to add a route table with internet gateway to the subnet.

aws ec2 create-route --route-table-id rtb-b86fe2dc --destination-cidr-block 0.0.0.0/0 --gateway-id igw-5d685a38

Step 7: Associate Route Table to a Subnet

Associate the route table with the second subnet using associate-route-table command and the ids.

aws ec2 associate-route-table --route-table-id rtb-b86fe2dc --subnet-id subnet-3b839262

Now our second subnet is a public subnet as we associated a route table with internet gateway rule. We can now launch an instance to the public subnet which can be accessed over the internet. If you launch an ec2 instance in the private subnet (first subnet – 10.0.1.0/24), you will not be able to access it as it does not have an internet gateway rule. But all the instances in a VPC can talk to each other using its private IP’s.

Launching an EC2 instance

Now we will launch an EC2 instance in the public subnet using CLI. I hope you have all the id’s noted down in a text file. We will be using those id’s for instance launch.

There are few parameters you should know before launching the instance.

1. AMI ID: id of the image (OS) that you want to launch.You can get this id from the AWS launch wizard as shown below.

2. Security Group ID: Create a security group and get the id.

3. Subnet ID

4. Key pair Name – Create a key pair and note down the name.

Execute the following command with relevant ID’s to launch the instance in public subnet.

aws ec2 run-instances --image-id ami-9abea4fb --count 1 --instance-type t2.micro --key-name test-key --security-group-ids sg-af7a50c8 --subnet-id subnet-3b839262 --associate-public-ip-address