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Add a python project about Route 53 Failover Record with Health Check that resolve #789 (#1053)
* route53 failover record * Reorganized stack structure * Adding alias record based health check for failover record * Changed container image of sample workload from personal sample app to managed sample app * Changed personal information to example information * Updated README file * Added instruction to use pre-made Route 53 HostedZone * Fixed the code to be deployed without previous resources. Extracted hosted zone and pass it as parameter to health check stacks example.com is reserved. Changes domain name to different name * Updated architecture diagram Move the email icon to outside of the region Added CloudWatch metrics that make alarm --------- Co-authored-by: Kihoon Kown <[email protected]> Co-authored-by: Junseong Jang <[email protected]> Co-authored-by: Michael Kaiser <[email protected]>
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‎python/route53-failover/README.md‎

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# CDK Failover DNS with Route 53 Health Check
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This sample project demonstrates how to create a Failover DNS record in Route 53 using a CDK application. It leverages the Route 53 Health Check feature to monitor the status of endpoints and automatically fail over to a backup endpoint in case of failure. Additionally, it configures SNS notifications to alert administrators when a failover event occurs, ensuring prompt awareness and response.
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## Architecture
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The architecture of this solution is illustrated in the following diagram:
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![Architecture Diagram](images/architecture.png)
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The key components of the architecture are:
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1. **Primary Endpoint**: The main endpoint that serves traffic under normal circumstances.
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2. **Secondary Endpoint**: The backup endpoint that takes over traffic when the primary endpoint fails.
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3. **Route 53 Hosted Zone**: The DNS hosted zone where the Failover DNS record is created.
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4. **Route 53 Health Checks**: Health checks that monitor the availability of the primary and secondary endpoints.
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5. **Route 53 Failover DNS Record**: The DNS record that routes traffic to the primary endpoint by default, but automatically switches to the secondary endpoint when the primary endpoint fails the health check.
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6. **SNS Topic**: The Simple Notification Service (SNS) topic that publishes notifications when a failover event occurs.
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7. **SNS Subscription**: The subscription to the SNS topic, which can be configured to deliver notifications via email or other channels.
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## Getting Started
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To get started with this project, follow these steps:
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1. Clone the repository.
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2. Install the required dependencies using `npm install`.
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3. Configure the necessary AWS credentials and environment variables.
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4. Select a Route 53 HostedZone that can be used for this project.
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5. **Provide the required context values in the `cdk.json` file, including `domain` refering the HostedZone, `email` to get notifications, `primaryRegion`, and `secondaryRegion` to deploy the sample application.**
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6. Deploy the CDK application using `cdk deploy`.
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Refer to the project's documentation for more detailed instructions and configuration options.

‎python/route53-failover/alias_healthcheck_record_stack.py‎

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from constructs import Construct
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from aws_cdk import (
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Stack,
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aws_route53 as route53,
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aws_elasticloadbalancingv2 as elbv2,
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aws_route53_targets as route53_targets,
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)
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class AliasHealthcheckRecordStack(Stack):
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def __init__(self, scope: Construct, construct_id: str, zone: route53.HostedZone, primaryLoadBalancer: elbv2.ILoadBalancerV2, secondaryLoadBalancer: elbv2.ILoadBalancerV2, **kwargs) -> None:
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super().__init__(scope, construct_id, **kwargs)
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# primary record
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primary = route53.ARecord(self, "PrimaryRecordSet",
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zone = zone,
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record_name="alias",
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target = route53.RecordTarget.from_alias(route53_targets.LoadBalancerTarget(primaryLoadBalancer)),
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)
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primaryRecordSet = primary.node.default_child
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primaryRecordSet.failover = "PRIMARY"
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primaryRecordSet.add_property_override('AliasTarget.EvaluateTargetHealth', True)
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primaryRecordSet.set_identifier = "Primary"
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# secondary record
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secondary = route53.ARecord(self, "SecondaryRecordSet",
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zone = zone,
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record_name="alias",
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target= route53.RecordTarget.from_alias(route53_targets.LoadBalancerTarget(secondaryLoadBalancer)),
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)
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secondaryRecordSet = secondary.node.default_child
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secondaryRecordSet.failover = "SECONDARY"
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secondaryRecordSet.add_property_override('AliasTarget.EvaluateTargetHealth', True)
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secondaryRecordSet.set_identifier = "Secondary"
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# # cloudwatch metric & alarm to SNS
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# snsTopic = sns.Topic(self, "AlarmNotificationTopic")
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# snsTopic.add_subscription(
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# EmailSubscription(email_address=email)
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# )
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# healthCheckMetric = cloudwatch.Metric(
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# metric_name="HealthCheckStatus",
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# namespace="AWS/Route53",
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# statistic="Minimum",
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# period=Duration.minutes(1),
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# region="us-east-1",
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# dimensions_map={
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# "HealthCheckId": primaryHealthCheck.attr_health_check_id
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# }
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# )
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# healthCheckAlarm = healthCheckMetric.create_alarm(self, 'HealthCheckFailureAlarm',
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# evaluation_periods=1,
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# threshold=1,
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# comparison_operator=cloudwatch.ComparisonOperator.LESS_THAN_THRESHOLD
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# )
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# healthCheckAlarm.add_alarm_action(SnsAction(snsTopic))

‎python/route53-failover/app.py‎

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#!/usr/bin/env python3
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import os
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import aws_cdk as cdk
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from fargate_app_stack import FargateAppStack
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from hosted_zone_stack import HostedZoneStack
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from healthcheck_alarm_stack import HealthcheckAlarmStack
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from alias_healthcheck_record_stack import AliasHealthcheckRecordStack
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app = cdk.App()
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domain=app.node.try_get_context('domain')
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email=app.node.try_get_context('email')
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primaryRegion=app.node.try_get_context('primaryRegion')
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secondaryRegion=app.node.try_get_context('secondaryRegion')
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account=os.getenv('CDK_DEFAULT_ACCOUNT')
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region=os.getenv('CDK_DEFAULT_REGION')
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# Sample app 1
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app1 = FargateAppStack(app, "PrimaryFargateApp", env=cdk.Environment(
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account=account,
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region=primaryRegion
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))
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# Sample app 2
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app2 = FargateAppStack(app, "SecondaryFargateApp", env=cdk.Environment(
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account=account,
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region=secondaryRegion
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))
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# Hosted Zone
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hostedZoneStack = HostedZoneStack(app, "HostedZone", domain=domain, env=cdk.Environment(
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account=account,
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region="us-east-1"
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))
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HealthcheckAlarmStack(
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app, "HealthCheckAlarm",
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zone=hostedZoneStack.zone,
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primaryLoadBalancer=app1.fargate_service.load_balancer,
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secondaryLoadBalancer=app2.fargate_service.load_balancer,
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email=email,
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env=cdk.Environment(
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account=account,
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region="us-east-1"
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),
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cross_region_references=True
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)
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AliasHealthcheckRecordStack(
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app, "AliasHealthCheckRecord",
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zone=hostedZoneStack.zone,
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primaryLoadBalancer=app1.fargate_service.load_balancer,
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secondaryLoadBalancer=app2.fargate_service.load_balancer,
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env=cdk.Environment(
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account=account,
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region="us-east-1"
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),
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cross_region_references=True
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)
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app.synth()

‎python/route53-failover/cdk.json‎

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{
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"app": "python3 app.py",
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"watch": {
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"include": [
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"**"
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],
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"exclude": [
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"README.md",
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"cdk*.json",
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"requirements*.txt",
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"source.bat",
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"**/__init__.py",
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"**/__pycache__",
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"tests"
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]
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},
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"context": {
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"@aws-cdk/aws-lambda:recognizeLayerVersion": true,
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"@aws-cdk/core:checkSecretUsage": true,
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"@aws-cdk/core:target-partitions": [
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"aws",
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"aws-cn"
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],
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"@aws-cdk-containers/ecs-service-extensions:enableDefaultLogDriver": true,
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"@aws-cdk/aws-ec2:uniqueImdsv2TemplateName": true,
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"@aws-cdk/aws-ecs:arnFormatIncludesClusterName": true,
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"@aws-cdk/aws-iam:minimizePolicies": true,
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"@aws-cdk/core:validateSnapshotRemovalPolicy": true,
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"@aws-cdk/aws-codepipeline:crossAccountKeyAliasStackSafeResourceName": true,
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"@aws-cdk/aws-s3:createDefaultLoggingPolicy": true,
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"@aws-cdk/aws-sns-subscriptions:restrictSqsDescryption": true,
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"@aws-cdk/aws-apigateway:disableCloudWatchRole": true,
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"@aws-cdk/core:enablePartitionLiterals": true,
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"@aws-cdk/aws-events:eventsTargetQueueSameAccount": true,
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"@aws-cdk/aws-iam:standardizedServicePrincipals": true,
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"@aws-cdk/aws-ecs:disableExplicitDeploymentControllerForCircuitBreaker": true,
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"@aws-cdk/aws-iam:importedRoleStackSafeDefaultPolicyName": true,
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"@aws-cdk/aws-s3:serverAccessLogsUseBucketPolicy": true,
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"@aws-cdk/aws-route53-patters:useCertificate": true,
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"@aws-cdk/customresources:installLatestAwsSdkDefault": false,
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"@aws-cdk/aws-rds:databaseProxyUniqueResourceName": true,
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"@aws-cdk/aws-codedeploy:removeAlarmsFromDeploymentGroup": true,
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"@aws-cdk/aws-apigateway:authorizerChangeDeploymentLogicalId": true,
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"@aws-cdk/aws-ec2:launchTemplateDefaultUserData": true,
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"@aws-cdk/aws-secretsmanager:useAttachedSecretResourcePolicyForSecretTargetAttachments": true,
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"@aws-cdk/aws-redshift:columnId": true,
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"@aws-cdk/aws-stepfunctions-tasks:enableEmrServicePolicyV2": true,
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"@aws-cdk/aws-ec2:restrictDefaultSecurityGroup": true,
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"@aws-cdk/aws-apigateway:requestValidatorUniqueId": true,
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"@aws-cdk/aws-kms:aliasNameRef": true,
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"@aws-cdk/aws-autoscaling:generateLaunchTemplateInsteadOfLaunchConfig": true,
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"@aws-cdk/core:includePrefixInUniqueNameGeneration": true,
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"@aws-cdk/aws-efs:denyAnonymousAccess": true,
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"@aws-cdk/aws-opensearchservice:enableOpensearchMultiAzWithStandby": true,
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"@aws-cdk/aws-lambda-nodejs:useLatestRuntimeVersion": true,
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"@aws-cdk/aws-efs:mountTargetOrderInsensitiveLogicalId": true,
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"@aws-cdk/aws-rds:auroraClusterChangeScopeOfInstanceParameterGroupWithEachParameters": true,
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"@aws-cdk/aws-appsync:useArnForSourceApiAssociationIdentifier": true,
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"@aws-cdk/aws-rds:preventRenderingDeprecatedCredentials": true,
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"@aws-cdk/aws-codepipeline-actions:useNewDefaultBranchForCodeCommitSource": true,
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"@aws-cdk/aws-cloudwatch-actions:changeLambdaPermissionLogicalIdForLambdaAction": true,
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"@aws-cdk/aws-codepipeline:crossAccountKeysDefaultValueToFalse": true,
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"@aws-cdk/aws-codepipeline:defaultPipelineTypeToV2": true,
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"@aws-cdk/aws-kms:reduceCrossAccountRegionPolicyScope": true,
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"@aws-cdk/aws-eks:nodegroupNameAttribute": true,
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"@aws-cdk/aws-ec2:ebsDefaultGp3Volume": true,
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"@aws-cdk/aws-ecs:removeDefaultDeploymentAlarm": true,
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"@aws-cdk/custom-resources:logApiResponseDataPropertyTrueDefault": false,
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"domain": "aws-cdk-samples.com",
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"email": "[email protected]",
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"primaryRegion": "us-east-1",
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"secondaryRegion": "us-west-2"
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}
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}

‎python/route53-failover/fargate_app_stack.py‎

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from aws_cdk import (
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aws_ec2 as ec2,
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aws_ecs as ecs,
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aws_ecs_patterns as ecs_patterns,
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CfnOutput, Stack
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)
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from constructs import Construct
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# Need to Change different app
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class FargateAppStack(Stack):
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def __init__(self, scope: Construct, id: str, **kwargs) -> None:
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super().__init__(scope, id, **kwargs)
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# Create VPC and Fargate Cluster
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# NOTE: Limit AZs to avoid reaching resource quotas
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vpc = ec2.Vpc(
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self, "MyVpc",
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max_azs=2
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)
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cluster = ecs.Cluster(
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self, 'Ec2Cluster',
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vpc=vpc
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)
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self.fargate_service = ecs_patterns.NetworkLoadBalancedFargateService(
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self, "FargateService",
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cluster=cluster,
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task_image_options=ecs_patterns.NetworkLoadBalancedTaskImageOptions(
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image=ecs.ContainerImage.from_registry("amazon/amazon-ecs-sample")
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)
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)
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self.fargate_service.service.connections.security_groups[0].add_ingress_rule(
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peer = ec2.Peer.ipv4(vpc.vpc_cidr_block),
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connection = ec2.Port.tcp(80),
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description="Allow http inbound from VPC"
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)
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CfnOutput(
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self, "LoadBalancerDNS",
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value=self.fargate_service.load_balancer.load_balancer_dns_name
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)

‎python/route53-failover/healthcheck_alarm_stack.py‎

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from constructs import Construct
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from aws_cdk import (
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Stack,
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Duration,
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aws_route53 as route53,
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aws_elasticloadbalancingv2 as elbv2,
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aws_route53_targets as route53_targets,
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aws_cloudwatch as cloudwatch,
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aws_sns as sns
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)
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from aws_cdk.aws_cloudwatch_actions import SnsAction
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from aws_cdk.aws_sns_subscriptions import EmailSubscription
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class HealthcheckAlarmStack(Stack):
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def __init__(self, scope: Construct, construct_id: str, zone: route53.HostedZone, primaryLoadBalancer: elbv2.ILoadBalancerV2, secondaryLoadBalancer: elbv2.ILoadBalancerV2, email: str, **kwargs) -> None:
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super().__init__(scope, construct_id, **kwargs)
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# primary record
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primaryHealthCheck = route53.CfnHealthCheck(self, "DNSPrimaryHealthCheck", health_check_config=route53.CfnHealthCheck.HealthCheckConfigProperty(
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fully_qualified_domain_name=primaryLoadBalancer.load_balancer_dns_name,
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type="HTTP",
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port=80
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))
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primary = route53.ARecord(self, "PrimaryRecordSet",
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zone = zone,
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record_name="failover",
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target = route53.RecordTarget.from_alias(route53_targets.LoadBalancerTarget(primaryLoadBalancer)),
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)
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primaryRecordSet = primary.node.default_child
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primaryRecordSet.failover = "PRIMARY"
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primaryRecordSet.health_check_id = primaryHealthCheck.attr_health_check_id
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primaryRecordSet.set_identifier = "Primary"
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# secondary record
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secondaryHealthCheck = route53.CfnHealthCheck(self, "DNSSecondaryHealthCheck", health_check_config=route53.CfnHealthCheck.HealthCheckConfigProperty(
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fully_qualified_domain_name=secondaryLoadBalancer.load_balancer_dns_name,
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type="HTTP",
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port=80,
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))
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secondary = route53.ARecord(self, "SecondaryRecordSet",
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zone = zone,
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record_name="failover",
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target= route53.RecordTarget.from_alias(route53_targets.LoadBalancerTarget(secondaryLoadBalancer)),
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)
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secondaryRecordSet = secondary.node.default_child
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secondaryRecordSet.failover = "SECONDARY"
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secondaryRecordSet.health_check_id = secondaryHealthCheck.attr_health_check_id
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secondaryRecordSet.set_identifier = "Secondary"
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# cloudwatch metric & alarm to SNS
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snsTopic = sns.Topic(self, "AlarmNotificationTopic")
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snsTopic.add_subscription(
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EmailSubscription(email_address=email)
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)
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healthCheckMetric = cloudwatch.Metric(
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metric_name="HealthCheckStatus",
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namespace="AWS/Route53",
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statistic="Minimum",
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period=Duration.minutes(1),
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region="us-east-1",
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dimensions_map={
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"HealthCheckId": primaryHealthCheck.attr_health_check_id
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}
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)
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healthCheckAlarm = healthCheckMetric.create_alarm(self, 'HealthCheckFailureAlarm',
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evaluation_periods=1,
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threshold=1,
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comparison_operator=cloudwatch.ComparisonOperator.LESS_THAN_THRESHOLD
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)
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healthCheckAlarm.add_alarm_action(SnsAction(snsTopic))

‎python/route53-failover/hosted_zone_stack.py‎

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from constructs import Construct
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from aws_cdk import (
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Stack,
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aws_route53 as route53,
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)
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class HostedZoneStack(Stack):
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def __init__(self, scope: Construct, construct_id: str, domain: str, **kwargs) -> None:
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super().__init__(scope, construct_id, **kwargs)
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# Test Env
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self.zone = route53.PublicHostedZone(self, "HostedZone", zone_name=domain)
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# use below code to use already created hosted zone
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# self.hostzone = route53.HostedZone.from_lookup(self, "HostedZone", domain_name=domain)

‎python/route53-failover/images/.gitignore‎

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*.drawio.bkp

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