If you want to retrieve the EC2 instance ID from within the instance itself, you can use the AWS Command Line Interface (AWS CLI) or query the instance metadata service.Lets discuss how to use the above methods:

Lets discuss how to use the above methods:

Using AWS CLI

Ensure that the AWS CLI is installed on your EC2 instance. You can install it using the following command:

sudo yum install aws-cli   # for Amazon Linux, CentOS, or RHEL

or

sudo apt-get install aws-cli   # for Ubuntu/Debian

Run the following AWS CLI command to retrieve the instance ID:

aws ec2 describe-instances --instance-id $(curl -s http://169.254.169.254/latest/meta-data/instance-id) --query 'Reservations[0].Instances[0].InstanceId' --output text

The above command uses the curl command to query the instance metadata service at http://169.254.169.254/latest/meta-data/instance-id after that uses the obtained instance ID to describe the instance and extract the ID.

Using Instance Metadata Service:

You can also query the instance metadata service from within the instance directly:

curl -s http://169.254.169.254/latest/meta-data/instance-id

This will return only the instance ID as a string.

Example:
If you prefer using a script, you can create a simple Python script:

import requests

def get_instance_id():
    try:
        response = requests.get("http://169.254.169.254/latest/meta-data/instance-id", timeout=2)
        if response.status_code == 200:
            return response.text
        else:
            return "Error: Unable to retrieve instance ID"
    except requests.RequestException as e:
        return f"Error: {e}"

instance_id = get_instance_id()
print("Instance ID:", instance_id)

Save this script as, for example, get_instance_id.py, and then run it on your EC2 instance:

python get_instance_id.py

This script uses the requests library to query the instance metadata service and retrieve the instance ID.

Select the method that suits your preference and environment. Method 1 (AWS CLI) is suitable for use in scripts and automation, while Method 2 (Instance Metadata Service) can be used directly from within the instance.