Automating AWS EC2 Instance Status Checks with Python

Prerequisites

Before running the script, make sure you have the following:

• AWS credentials configured on your machine
• Required Python libraries installed: boto3, schedule
• Environment variables set for EMAIL_ADDRESS and EMAIL_PASSWORD to send email notifications

Script Walkthrough

Let’s go through the script step by step:

1. Importing Libraries: The script starts by importing the necessary libraries, including boto3 for interacting with AWS services, schedule for scheduling tasks, logging for logging messages, smtplib for sending emails, time for adding delays, and os for retrieving environment variables.
2. Configuring Logging: The script configures logging to display log messages with timestamps and log levels.
3. Initializing AWS Client: The script retrieves the AWS region from an environment variable or defaults to ‘us-east-1’. It then initializes the boto3 client for EC2 in the specified region.
4. Retrieving Email Credentials: The script retrieves the email address and password from environment variables to be used for sending notifications.
5. Sending Email Notification: The send_notification function is responsible for sending an email notification when an instance’s status is not ‘ok’. It uses the smtplib library to establish a connection with the SMTP server, logs in with the provided credentials, and sends an email with the instance details and status.
6. Checking Instance Status: The check_instance_status function is the core of the script. It uses the describe_instance_status API to retrieve the status of all instances in the specified region. It iterates over the instances and checks their instance status and system status. If either status is not ‘ok’, it calls the send_notification function to send an email notification.
7. Scheduling the Status Check: The script uses the schedule library to schedule the check_instance_status function to run every 5 seconds (or any desired interval).
8. Running the Script: The script enters a loop that continuously runs the scheduled tasks until it is terminated by the user using a keyboard interrupt (Ctrl+C).

Error Handling

The script includes error handling to catch and log any exceptions that may occur during execution. It handles specific exceptions like ClientError and BotoCoreError for AWS-related errors and catches any other exceptions using a generic Exception block.

For those interested in implementing or adapting this script, here’s the complete code:

import boto3
import schedule
import logging
import smtplib
import time
import os
from botocore.exceptions import ClientError, BotoCoreError

# Configure logging
logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')

# Retrieve the AWS region from an environment variable or default to a specific region
AWS_REGION = os.environ.get('AWS_REGION', 'us-east-1')

# Initialize boto3 client for a specific region
ec2_client = boto3.client('ec2', region_name=AWS_REGION)

# Retrieve email address and password from environment variables
EMAIL_ADDRESS = os.environ.get('EMAIL_ADDRESS')
EMAIL_PASSWORD = os.environ.get('EMAIL_PASSWORD')


def send_notification(instance_id, status_type, status):
    try:
        with smtplib.SMTP('smtp.gmail.com', 587) as smtp:
            smtp.starttls()
            smtp.ehlo()
            smtp.login(EMAIL_ADDRESS, EMAIL_PASSWORD)
            subject = f"Instance {instance_id} - {status_type} Status: {status}"
            body = f"Instance {instance_id} has {status_type} status: {status}. Please check the instance."
            msg = f"Subject: {subject}\n\n{body}"
            smtp.sendmail(EMAIL_ADDRESS, EMAIL_ADDRESS, msg)
            logging.info(f"Email notification sent for instance {instance_id}")
    except smtplib.SMTPAuthenticationError as e:
        logging.error(f"SMTP authentication error: {e}")
    except Exception as e:
        logging.error(f"An error occurred while sending email: {e}")


def check_instance_status():
    try:
        # Describe all instances' status in the specified region
        paginator = ec2_client.get_paginator('describe_instance_status')
        page_iterator = paginator.paginate(IncludeAllInstances=True)

        for page in page_iterator:
            for status in page.get('InstanceStatuses', []):
                instance_id = status.get('InstanceId', 'N/A')
                ins_status = status['InstanceStatus'].get('Status', 'N/A')
                sys_status = status['SystemStatus'].get('Status', 'N/A')
                state = status['InstanceState'].get('Name', 'N/A')
                logging.info(
                    f"Instance {instance_id} in region {AWS_REGION} is {state} with instance status {ins_status} and system status {sys_status}")

                # Send notification if instance or system status is not 'ok'
                if ins_status != 'ok':
                    send_notification(instance_id, "Instance", ins_status)
                if sys_status != 'ok':
                    send_notification(instance_id, "System", sys_status)

    except (ClientError, BotoCoreError) as e:
        logging.error(f"An AWS error occurred: {e}")
    except Exception as e:
        logging.error(f"An error occurred: {e}")


# Schedule the function to run every 5 seconds (or use a configurable interval)
schedule.every(5).seconds.do(check_instance_status)

try:
    # Run the schedule as long as the script is running
    while True:
        schedule.run_pending()
        time.sleep(1)
except KeyboardInterrupt:
    logging.info("Script was terminated by the user")