AWS Lambda function to check if PHP-FPM is running and restart it, if not running

CheckAndRestartPhpFpm.py

import boto3
import os
import logging
import time

# Setup logging
logger = logging.getLogger()
logger.setLevel(logging.INFO)

elasticbeanstalk = boto3.client('elasticbeanstalk')
ec2 = boto3.client('ec2')
ssm = boto3.client('ssm')

# Environment and instance details
ENVIRONMENT_NAME = os.environ['ENVIRONMENT_NAME']
RETRY_COUNT = 10
RETRY_DELAY = 5  # seconds

def check_php_fpm(instance_id):
    """Checks if php-fpm is running on the instance."""
    try:
        command = "sudo systemctl is-active php-fpm"
        response = ssm.send_command(
            InstanceIds=[instance_id],
            DocumentName="AWS-RunShellScript",
            Parameters={"commands": [command]},
        )
        command_id = response['Command']['CommandId']

        # Retry mechanism to check the command status
        for _ in range(RETRY_COUNT):
            time.sleep(RETRY_DELAY)
            try:
                output = ssm.get_command_invocation(
                    CommandId=command_id,
                    InstanceId=instance_id,
                )
                if output['Status'] in ['Success', 'Failed', 'Cancelled', 'TimedOut']:
                    break
            except ssm.exceptions.InvocationDoesNotExist:
                logger.warning(f"Invocation does not exist for instance {instance_id}, retrying...")

        logger.info(f"Instance {instance_id} php-fpm status: {output['StandardOutputContent'].strip()}")
        return output['StandardOutputContent'].strip() == 'active'
    except ssm.exceptions.InvalidInstanceId as e:
        logger.error(f"Invalid instance ID: {instance_id}. Error: {str(e)}")
        return False
    except Exception as e:
        logger.error(f"Error checking php-fpm status on instance {instance_id}. Error: {str(e)}")
        return False

def restart_app_servers():
    """Restarts all instances in the Elastic Beanstalk environment."""
    try:
        response = elasticbeanstalk.restart_app_server(
            EnvironmentName=ENVIRONMENT_NAME
        )
        logger.info(f"Restarted app servers in environment {ENVIRONMENT_NAME}")
        return response
    except Exception as e:
        logger.error(f"Error restarting app servers in environment {ENVIRONMENT_NAME}. Error: {str(e)}")
        return None

def lambda_handler(event, context):
    try:
        response = elasticbeanstalk.describe_environment_resources(
            EnvironmentName=ENVIRONMENT_NAME
        )
        instances = response['EnvironmentResources']['Instances']

        for instance in instances:
            instance_id = instance['Id']
            if not check_php_fpm(instance_id):
                restart_app_servers()
                break

        return {
            'statusCode': 200,
            'body': 'Checked php-fpm and restarted app servers if necessary.'
        }
    except Exception as e:
        logger.error(f"Error in lambda_handler. Error: {str(e)}")
        return {
            'statusCode': 500,
            'body': 'Error in lambda_handler.'
        }