Ejercicio: Recuperación ante Desastres con AWS DRS ​

# infrastructure/scripts/health_checks/custom_health_check.py
import boto3
import requests
import json

def check_application_health():
    endpoints = [
        {"url": "https://api.example.com/health", "weight": 2},
        {"url": "https://app.example.com/status", "weight": 1},
        {"url": "https://db.example.com/ping", "weight": 3}
    ]
    
    total_score = 0
    max_score = sum(ep["weight"] for ep in endpoints)
    
    for endpoint in endpoints:
        try:
            response = requests.get(endpoint["url"], timeout=5)
            if response.status_code == 200:
                total_score += endpoint["weight"]
        except:
            continue
    
    health_percentage = (total_score / max_score) * 100
    return health_percentage >= 80

def update_route53_health_check():
    route53 = boto3.client('route53')
    health_check_id = 'your-health-check-id'
    
    if check_application_health():
        status = 'Success'
    else:
        status = 'Failure'
    
    route53.update_health_check(
        HealthCheckId=health_check_id,
        HealthCheckVersion=2,
        Status=status
    )

# infrastructure/scripts/failover/execute_failover.py
import boto3
import json
import time
from datetime import datetime

class DRFailover:
    def __init__(self):
        self.drs = boto3.client('drs')
        self.route53 = boto3.client('route53')
        self.sns = boto3.client('sns')
        
    def initiate_failover(self, source_servers):
        try:
            # Registrar inicio de failover
            start_time = datetime.now()
            
            # Iniciar recuperación de servidores
            job_ids = []
            for server in source_servers:
                response = self.drs.initialize_service(
                    sourceServerID=server['id']
                )
                job_ids.append(response['jobID'])
            
            # Monitorear progreso
            while not self._all_jobs_complete(job_ids):
                time.sleep(30)
            
            # Actualizar DNS
            self._update_dns_records()
            
            # Notificar completitud
            self._send_notification(
                f"Failover completed successfully in "
                f"{(datetime.now() - start_time).total_seconds()} seconds"
            )
            
            return True
            
        except Exception as e:
            self._send_notification(f"Failover failed: {str(e)}")
            raise
            
    def _all_jobs_complete(self, job_ids):
        for job_id in job_ids:
            response = self.drs.describe_job(jobID=job_id)
            if response['status'] != 'completed':
                return False
        return True
        
    def _update_dns_records(self):
        with open('infrastructure/configs/failover_policy.json', 'r') as f:
            policy = json.load(f)
        
        update_batch = {
            'Changes': [
                {
                    'Action': 'UPSERT',
                    'ResourceRecordSet': {
                        'Name': 'app.example.com',
                        'Type': 'A',
                        'SetIdentifier': 'failover',
                        'Region': policy['failoverConfig']['secondaryRegion'],
                        'AliasTarget': {
                            'HostedZoneId': 'ZONE_ID',
                            'DNSName': 'dr-endpoint.example.com',
                            'EvaluateTargetHealth': True
                        }
                    }
                }
            ]
        }
        
        self.route53.change_resource_record_sets(
            HostedZoneId='ZONE_ID',
            ChangeBatch=update_batch
        )
        
    def _send_notification(self, message):
        self.sns.publish(
            TopicArn='arn:aws:sns:region:account:DR-Notifications',
            Message=message,
            Subject='DR Failover Status'
        )

# infrastructure/scripts/failover/validate_failover.py
import requests
import dns.resolver
import json

def validate_failover():
    checks = {
        'dns_propagation': check_dns_propagation(),
        'application_health': check_application_health(),
        'data_consistency': check_data_consistency(),
        'performance': check_performance_metrics()
    }
    
    return all(checks.values()), checks

def check_dns_propagation():
    resolver = dns.resolver.Resolver()
    resolver.nameservers = ['8.8.8.8', '1.1.1.1']
    
    try:
        answers = resolver.resolve('app.example.com', 'A')
        expected_ip = get_dr_endpoint_ip()
        return str(answers[0]) == expected_ip
    except:
        return False

def check_application_health():
    endpoints = [
        '/api/health',
        '/api/status',
        '/api/metrics'
    ]
    
    results = []
    for endpoint in endpoints:
        try:
            response = requests.get(f'https://app.example.com{endpoint}')
            results.append(response.status_code == 200)
        except:
            results.append(False)
    
    return all(results)

def check_data_consistency():
    # Implementar verificaciones de consistencia de datos
    pass

def check_performance_metrics():
    # Implementar verificaciones de rendimiento
    pass

# monitoring/alerts/failover_alerts.py
def setup_failover_alerts():
    cloudwatch = boto3.client('cloudwatch')
    
    alerts = [
        {
            'name': 'FailoverInitiated',
            'metric': 'FailoverStatus',
            'threshold': 1,
            'period': 60,
            'evaluation_periods': 1
        },
        {
            'name': 'HighRecoveryTime',
            'metric': 'RecoveryTime',
            'threshold': 14400,  # 4 hours
            'period': 300,
            'evaluation_periods': 1
        }
    ]
    
    for alert in alerts:
        cloudwatch.put_metric_alarm(
            AlarmName=alert['name'],
            MetricName=alert['metric'],
            Namespace='DR/Failover',
            Period=alert['period'],
            EvaluationPeriods=alert['evaluation_periods'],
            Threshold=alert['threshold'],
            ComparisonOperator='GreaterThanThreshold',
            AlarmActions=['arn:aws:sns:region:account:DR-Alerts']
        )

# infrastructure/ssm/automation/test_automation.py
import boto3
import json

def create_test_automation():
    ssm = boto3.client('ssm')
    
    document = {
        "schemaVersion": "0.3",
        "description": "Automation for DR testing",
        "parameters": {
            "TestType": {
                "type": "String",
                "description": "Type of DR test to perform",
                "allowedValues": [
                    "FullFailover",
                    "PartialFailover",
                    "ComponentTest"
                ]
            }
        },
        "mainSteps": [
            {
                "name": "PrepareTestEnvironment",
                "action": "aws:runCommand",
                "inputs": {
                    "DocumentName": "AWS-RunShellScript",
                    "Parameters": {
                        "commands": [
                            "#!/bin/bash",
                            "echo 'Preparing test environment'",
                            "# Setup test data",
                            "# Configure monitoring"
                        ]
                    }
                }
            },
            {
                "name": "ExecuteTest",
                "action": "aws:executeAutomation",
                "inputs": {
                    "DocumentName": "DR-Recovery",
                    "RuntimeParameters": {
                        "EnvironmentType": "test"
                    }
                }
            },
            {
                "name": "ValidateResults",
                "action": "aws:executeScript",
                "inputs": {
                    "Runtime": "python3.8",
                    "Handler": "validate_test_results",
                    "Script": "validate_results.py"
                }
            }
        ]
    }
    
    ssm.create_document(
        Content=json.dumps(document),
        Name='DR-TestAutomation',
        DocumentType='Automation',
        DocumentFormat='JSON'
    )

# testing/dr_test_plan.py
class DRTestPlan:
    def __init__(self):
        self.ssm = boto3.client('ssm')
        self.drs = boto3.client('drs')
        
    def execute_test_plan(self, test_type):
        test_cases = {
            'FullFailover': self._full_failover_test,
            'PartialFailover': self._partial_failover_test,
            'ComponentTest': self._component_test
        }
        
        test_function = test_cases.get(test_type)
        if test_function:
            return test_function()
        else:
            raise ValueError(f"Unknown test type: {test_type}")
    
    def _full_failover_test(self):
        steps = [
            self._validate_replication_status,
            self._execute_failover,
            self._verify_applications,
            self._test_data_consistency,
            self._measure_recovery_time
        ]
        
        results = []
        for step in steps:
            result = step()
            results.append(result)
            if not result['success']:
                break
                
        return {
            'testType': 'FullFailover',
            'steps': results,
            'overallSuccess': all(r['success'] for r in results)
        }
    
    def _validate_replication_status(self):
        try:
            response = self.drs.describe_source_servers()
            all_healthy = all(
                server['state'] == 'HEALTHY'
                for server in response['items']
            )
            return {
                'step': 'ValidateReplication',
                'success': all_healthy,
                'details': response
            }
        except Exception as e:
            return {
                'step': 'ValidateReplication',
                'success': False,
                'error': str(e)
            }

# testing/validation/test_validator.py
class DRTestValidator:
    def __init__(self):
        self.cloudwatch = boto3.client('cloudwatch')
        
    def validate_recovery_metrics(self, test_results):
        metrics = {
            'RecoveryTime': self._validate_recovery_time,
            'DataConsistency': self._validate_data_consistency,
            'ApplicationHealth': self._validate_application_health
        }
        
        validation_results = {}
        for metric_name, validator in metrics.items():
            validation_results[metric_name] = validator(test_results)
            
        return validation_results
    
    def _validate_recovery_time(self, results):
        recovery_time = results.get('recoveryTime', float('inf'))
        return {
            'metric': 'RecoveryTime',
            'value': recovery_time,
            'success': recovery_time <= 14400,  # 4 hours
            'threshold': 14400
        }
    
    def _validate_data_consistency(self, results):
        consistency_check = results.get('dataConsistency', {})
        return {
            'metric': 'DataConsistency',
            'value': consistency_check.get('percentage', 0),
            'success': consistency_check.get('percentage', 0) >= 99.9,
            'threshold': 99.9
        }

# reporting/test_report_generator.py
class DRTestReportGenerator:
    def generate_report(self, test_results):
        report = {
            'executionDate': datetime.now().isoformat(),
            'summary': self._generate_summary(test_results),
            'details': self._generate_details(test_results),
            'recommendations': self._generate_recommendations(test_results)
        }
        
        return self._format_report(report)
    
    def _generate_summary(self, results):
        return {
            'testType': results['testType'],
            'overallSuccess': results['overallSuccess'],
            'recoveryTime': results.get('recoveryTime'),
            'criticalIssues': len([
                step for step in results['steps']
                if not step['success'] and step.get('critical', True)
            ])
        }
    
    def _format_report(self, report):
        template = """
        # DR Test Report
        
        ## Summary
        - Test Type: {testType}
        - Overall Success: {overallSuccess}
        - Recovery Time: {recoveryTime}
        - Critical Issues: {criticalIssues}
        
        ## Details
        {details}
        
        ## Recommendations
        {recommendations}
        """
        
        return template.format(**report)