Creating an EC2 Instance with AWS CLI: A Simple Tutorial

Amazon EC2 (Elastic Compute Cloud) is a core service in AWS that allows users to launch and manage virtual machines in the cloud. While the AWS Management Console is commonly used to create and manage EC2 instances, the AWS Command Line Interface (CLI) offers a powerful way to automate the process, especially in scripts and infrastructure-as-code setups. This guide walks you through launching an EC2 instance using the AWS CLI.

Prerequisites: Setting Up AWS CLI and Configuring Credentials

Before launching an EC2 instance, would you like to know What is AWS CLI?

You can refer to this article What is AWS CLI?

In this article, we will look into the process of launching instances that is through AWS CLI(Command Line Interface). 

Step-by-Step Guide to Creating an EC2 Instance Using AWS CLI

So, let's begin with AWS CLI by launching an EC2 Instance using it. Creating an instance with AWS CLI is the same as launching one with AWS console. Open your command prompt as administrator by right-clicking on it.

Creating a VPC

The first thing to do is to create a VPC(virtual private cloud) under which an EC2 instance will be launched. For creating a VPC in CLI type the given command on the cmd.

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

Here the CIDR block I have taken is 10.0.0.0/16, you can change it as per your need. After running this command following output will be given in a JSON format. Note the vpcId . 

Creating Subnets

Next, create two subnets and make one as public to make it accessible from the internet. To do so use the below command:

aws ec2 create-subnet --vpc-id <vpcId> --cidr-block 10.0.1.0/24

Note the SubnetId generated here, so that this subnet can be made as public later on. The CIDR block we have used here is 10.0.1.0/24.  

 Now create a second subnet with CIDR block 10.0.0.0/24. (CIDR block values can be changed as per user needs):

aws ec2 create-subnet --vpc-id <vpcId> --cidr-block 10.0.0.0/24

Creating Internet Gateway

Internet gateway is used by the private subnet to access the internet for its updates and other packages installations. Create an internet gateway by using the following command:

aws ec2 create-internet-gateway

After the internet gateway is created, note the InternetGatewayId and to attach this internet gateway to the already created VPC. To do so use the below command:

aws ec2 attach-internet-gateway --vpc-id <vpcId> --internet-gateway-id <InternetGatewayId>

Here type the noted vpcId (in place of <vpcId>) and InternetGatewayId (in place of <InternetGatewayId>)

Creating Route Table

The next step is to create a route table and assigning it to the already created VPC. After creating the route table assign the route to this route table. Commands for the same are as given.

aws ec2 create-route-table --vpc-id <vpcId>

Now, use the RouteTableId and use it in the next step:

aws ec2 create-route --route-table-id <RouteTableId> 
              --destination-cidr-block 0.0.0.0/0 --gateway-id <nternetGatewayI>

Here we have used the 0.0.0.0/0 as destination CIDR block.

Viewing the Route Table and Subnets

To check whether route table and subnets are created and assigned successfully use the below commands:

aws ec2 describe-route-tables --route-table-id <RouteTableId>

aws ec2 describe-subnets --filters "Name=vpc-id,Values=<vpcId>"
                         --query "Subnets[*].{ID:SubnetId,CIDR:CidrBlock}"

Here replace your vpcId in place of <vpcId>.

 Associating Route Table and Modifying Subnet 

The next step is to associate the route table with the subnet and making the same subnet as public by mapping the public IP address to it. Enter the SubnetId and RouteTableId that you noted earlier. To associate route table type...

Type:

aws ec2 associate-route-table --subnet-id <SubnetId> --route-table-id <RouteTableId>

To map the public IP to the subnet, use the below command:

aws ec2 modify-subnet-attribute --subnet-id <SubnetId> --map-public-ip-on-launch

Creating Key Pair and Security Group

The most important step is to create a key pair. This key pair must be kept safe and secure with the user so that the person can access the EC2 instance created using this key pair.

Now, create the key-pair using the below command:

aws ec2 create-key-pair --key-name AWS-Keypair --query "KeyMaterial" 
                        --output text > "C:\AWS\AWS_Keypair.pem"

Here we have named the key pair file(.pem file) as AWS-Keypair and the path where our file will be downloaded is C:\AWS\AWS_Keypair.pem. Both these things can be changed by the user.

For security group use the below commands:

aws ec2 create-security-group --group-name <security-group-name> --description "<description>"
                              --vpc-id <vpcId>

Here provide name and description to the security group and add it in place of <security-group-name> and <description> respectively. Note the GroupId and use it in the next step.

aws ec2 authorize-security-group-ingress --group-id <GroupId> 
                                         --protocol tcp --port 22 --cidr 0.0.0.0/0

The protocol/port we use here is TCP/22.

Running the EC2 Instance

Finally, after all the setup completed successfully now the time is to run the instance. For running the EC2 Instance use the command as given below.

aws ec2 run-instances --image-id <ami-id> --count 1 --instance-type t2.micro 
                      --key-name <Keypair-name> --security-group-ids <SecurityGroupId> 
                      --subnet-id <SubnetId>

At this step, you will need an AMI(Amazon Machine Image) image ID. For this login to your AWS Console and choose any AMI of your type. Copy the image id and replace it here in place of <ami-id>.  Also use your key pair name, security group id, and subnet id at the correct place in the above command. Also, make a note of the InstanceId.

Viewing the Instance 

Now after the instance status is "running" type the command to view the complete details of the EC2 instance that you just created:

aws ec2 describe-instances --instance-id <InstanceId>

Enter the InstanceId you noted at the above step.

Verifying the EC2 Instance 

To verify whether the EC2 instance created using the AWS CLI is created as per need, log in to your AWS Console and open the EC2 service and check for the instance.

Conclusion

Launching an EC2 instance using AWS CLI provides greater control and flexibility for automating cloud infrastructure. By following this step-by-step guide, you can quickly spin up virtual machines, manage them efficiently, and automate recurring tasks, all while gaining a deeper understanding of how AWS operates behind the scenes. Whether you're managing a single instance or deploying an entire fleet of servers, AWS CLI is an invaluable tool for streamlining your cloud operations.