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Building the Bookstore in your Secondary Region (Singapore)

We completed building the bookstore in the primary region (Ireland) in the previous module. In this module, we will build the same Bookstore in Singapore region and configure the replication of Aurora MySQL for the Blog content, S3 bucket for static contects, and DynamoDB tables for the books/order/cart data from the primary region (Ireland) to the secondary region (Singapore).

2-1. Building your Book Blog using AWS CDK in your Secondary Region (Singapore)

Go back to your Cloud9 (that you created in Ireland), and execute following commands. It will take around 15 mins.

Let's make sure your environment variable MYSUBDOMAIN is correctly set. Enter the same MYSUBDOMAIN as you did previously from module 1.

export MYSUBDOMAIN=<enter a 8 char unique subdomain name with lower case, eg: team1234>

Similar to Ireland region, before you do the S3 replication, let's create the new S3 bucket for the reactJS app in Singapore (ap-southeast-1) region.

aws s3api create-bucket \
  --bucket arc309-singapore-$MYSUBDOMAIN-bookstore \
  --region ap-southeast-1 \
  --create-bucket-configuration LocationConstraint=ap-southeast-1

cd ~/environment/MultiRegion-Modern-Architecture/wordpress-lab/

export hostedZoneID=`aws cloudformation describe-stacks --stack-name hostedZone --region eu-west-1 \
 --query "Stacks[0].Outputs[?OutputKey=='hostedZoneID'].OutputValue" --output text`
export hostedZoneName=$MYSUBDOMAIN.multi-region.xyz
export AWS_DEFAULT_REGION=ap-southeast-1
npx cdk@1.22.0 bootstrap
npx cdk@1.22.0 deploy Wordpress-Secondary

CDK

Do you wish to deploy these changes (y/n)?. Enter "y"

CDK

Now, your Book Blog in Singapore is completed. However, you will find 503 Service Temporarily Unavailable error if you verify https://secondary.blog.<MYSUBDOMAIN>.multi-region.xyz/ as the wordpress is not connected the Aurora MySQL in Singapore region yet. We will configure this in the next section.

2-2. Replication of Aurora, S3, and DynamoDB

In this section, we will configure the replication of Aurora MySQL for the Blog content, S3 bucket for static contents, and DynamoDB tables for the books/order/cart data from the primary region (Ireland) to the secondary region (Singapore).

However, replication of Aurora MySQL and S3 is optional configuration for the Bookstore Failover testing in the next module. Hence, you can skip it now if you have no time to configure.

1. Enable Aurora MySQL Read replica in Singapore region (Optional)

Aurora MySQL Read replica helps you have a redundancy plan. The replica in `Singapore` region can be promoted as the primary database when the primary database in the primary region (`Ireland`) has issues.

Go back to Cloud9, and execute the following commands to enable the read replica of Aurora MySQL in Singapore region from Ireland region using the AWS CLI.

  • replication-source-identifier: Get from Cloudformation stack Wordpress-Primary in Ireland Region. Or use the following command in Cloud9.
export ReplicationSourceIdentifier=`aws cloudformation describe-stacks --stack-name Wordpress-Primary --region eu-west-1 \
    --query "Stacks[0].Outputs[?OutputKey=='RDSreplicationsourceidentifier'].OutputValue" --output text`
echo $ReplicationSourceIdentifier
  • vpc-security-group-ids: Get from Cloudformation stack Wordpress-Secondary in Singapore Region. Or use the following command in Cloud9.
export VpcSecurityGroupIds=`aws cloudformation describe-stacks --stack-name Wordpress-Secondary --region ap-southeast-1 \
    --query "Stacks[0].Outputs[?OutputKey=='WordpressDBsecurityGroupId'].OutputValue" --output text`
echo $VpcSecurityGroupIds

CLI to create read replica of Aurora MySQL in Singapore region.

aws rds create-db-cluster \
  --db-cluster-identifier arc309-replica-cluster \
  --engine aurora \
  --replication-source-identifier $ReplicationSourceIdentifier \
  --vpc-security-group-ids $VpcSecurityGroupIds \
  --db-subnet-group-name secondaryregion-wordpressdb-subnetgroup \
  --source-region eu-west-1 \
  --region ap-southeast-1

Verify the RDS replication cluster is created in Singapore region.

aws rds describe-db-clusters --db-cluster-identifier arc309-replica-cluster --region ap-southeast-1

Create RDS read replica instance.

aws rds create-db-instance \
  --db-instance-identifier arc309-replica-instance \
  --db-cluster-identifier arc309-replica-cluster \
  --db-instance-class db.t3.small \
  --engine aurora \
  --region ap-southeast-1

Verify RDS cluster creation in RDS console in Singapore region. Replica Aurora

Provisioning the Aurora replica instance can take a while takes for a while, you can procced the next step while the instance is being deployed.

2. Enable S3 replication for Web contents replication (Optional)

This S3 replication will replicate the static contents from Ireland region to Singapore whenever there is an update.

Follow the steps to enable the S3 replication using the AWS CLI in Cloud9. The destination bucket name should be your bucket name in Singarpore that you created above such as arc309-singapore-$MYSUBDOMAIN-bookstore.

aws s3api put-bucket-versioning \
  --bucket arc309-singapore-$MYSUBDOMAIN-bookstore \
  --versioning-configuration Status=Enabled
aws s3 website s3://<arc309-singapore-$MYSUBDOMAIN-bookstore>/ --index-document index.html

Add replication configuration to the source bucket in Ireland region. Save the following JSON in a file called replication.json to the your Cloud9. You need S3 replication role ARN for this exercise. You can find it in the output table of your CloudFormation stack (MyBookstoreIreland) in Ireland or execute following command in the Cloud9.

export ReplicationArnRole=`aws cloudformation describe-stacks --stack-name MyBookstoreIreland --region eu-west-1 \
     --query "Stacks[0].Outputs[?OutputKey=='S3replicationRole'].OutputValue" --output text`

copy and paste the following command to create a replication.json file:

echo '{
  "Role": "'$ReplicationArnRole'",
  "Rules": [
    {
      "Status": "Enabled",
      "Priority": 1,
      "DeleteMarkerReplication": { "Status": "Disabled" },
      "Filter": {},
      "Destination": {
        "Bucket": "arn:aws:s3:::arc309-singapore-'$MYSUBDOMAIN'-bookstore"
      }
    }
  ]
}' > replication.json

aws s3api put-bucket-replication \
  --replication-configuration file://replication.json \
  --bucket arc309-ireland-$MYSUBDOMAIN-bookstore

You can check the replication configuration in S3 console. Replica S3

S3 doesn't replicate objects retroactively. S3 Objects that existed before you added the replication configuration to the bucket aren't replicated to the new desination bucket. Hence, you need to sync the existing content to the new bucket in Singapore with following command.

aws s3 sync s3://arc309-ireland-$MYSUBDOMAIN-bookstore s3://arc309-singapore-$MYSUBDOMAIN-bookstore

3. Enable DynamoDB Global Tables using Console

Let's take a look at continuous replicating the data in DynamoDB from the primary region (Ireland) to the secondary region (Singapore) so that there is always a backup.

We will be using a feature of DynamoDB Global Tables for this. Any changes made to any items in any replica tables will be replicated to all of the other replicas within the same global table. In a global table, a newly-written item is usually propagated to all replica tables within seconds.

However, conflicts can arise if applications update the same item in different regions at about the same time. To ensure eventual consistency, DynamoDB global tables use a “last writer wins” reconciliation between concurrent updates, where DynamoDB makes a best effort to determine the last writer.

Follow the steps to create a global table of Book, Order, Cart form the Ireland to Singapore regions using the console.

Go to DynamoDB in Ireland. Select Books table, go to Global Tables tab, and click Add region Replica DynamoDVB

Select Singapore, and click Continue. Replica DynamoDVB

If you get the Internal Error message in the creation, please close the window and try again.

Do the same steps or bookstore-Orders and bookstore-Cart tables.

Now, you completed the replication across two regions for Aurora MySQL, S3, and DynamoDB. It's time to build the Bookstore eb/App layer in Singapore.

2-3. Building the Bookstore using Cloudformation in your Secondary Region (Singapore)

Step-by-step instructions

  1. Let's "grep" all the variables we need from the Wordpress-Primary stack in Cloudformation via the commands below:
export vpcSingapore=`aws cloudformation describe-stacks --stack-name Wordpress-Secondary \
--region ap-southeast-1 \
--query "Stacks[0].Outputs[?OutputKey=='SecondaryRegionVpcIdapsoutheast1'].OutputValue" \
--output text`
echo $vpcSingapore

export subnetSingapore=`aws cloudformation describe-stacks --stack-name Wordpress-Secondary \
--region  ap-southeast-1 \
--query "Stacks[0].Outputs[?OutputKey=='SecondaryRegionprivatesubnetforElasticache'].OutputValue" \
--output text`
echo $subnetSingapore

export orderDdbArn=`aws dynamodb describe-table --table-name bookstore-Orders \
--region ap-southeast-1 \
--query 'Table.LatestStreamArn'`
echo $orderDdbArn

export cognitoIrelandPool=`aws cloudformation describe-stacks --stack-name MyBookstoreIreland \
--region eu-west-1 \
--query "Stacks[0].Outputs[?OutputKey=='UserPool'].OutputValue" \
--output text`
echo $cognitoIrelandPool
  1. Let's create the ReactJS app with this aws command via AWS cloudformation:
aws cloudformation create-stack --stack-name MyBookstoreSingapore \
--template-url https://arc309-bookstore-ap-southeast-1.s3-ap-southeast-1.amazonaws.com/arc309_secondary.yaml \
--capabilities CAPABILITY_NAMED_IAM \
--parameters ParameterKey=ProjectName,ParameterValue=bookstore \
ParameterKey=AssetsBucketName,ParameterValue=arc309-singapore-$MYSUBDOMAIN-bookstore \
ParameterKey=bookstoreVPC,ParameterValue=$vpcSingapore \
ParameterKey=bookstoreSubnet1,ParameterValue=$subnetSingapore \
ParameterKey=OrderTableStreamARN,ParameterValue=$orderDdbArn \
ParameterKey=UserPool,ParameterValue=$cognitoIrelandPool

This CloudFormation template may take around 10 mins. You can proceed the next steps.

Update Blog DB connection with Read Replica in Singapore (Optional)

As we mentioned above, the replication of Aurora MySQL is optional configuration for the Bookstore Failover testing in the next module. Hence, you can skip it now if you have no time to configure.

Update Blog DB connection with Read Replica in Singapore (Optional)

You remember the Book Blog you created above had 503 Service Temporarily Unavailable error due to the Fargate didn't connect to Aurora MySQL in Singapore. You can find the endpoint of Read Replica in Singapore with the following commands:

aws rds describe-db-instances \
--db-instance-identifier arc309-replica-instance \
--region ap-southeast-1 \
--query "DBInstances[0].Endpoint.Address" --output text

Go to ECS in Singapore region, select WordpressSecondarywordpresssvcTaskDefXXXXXXXX task in Task Definition, and click Create new revision. ECS Select web container and update WORDPRESS_DB_HOST with the above Aurora Read Replica endpoint. Click Update. ECS

It goes back to Create new revision of Task Definition screen. Please scroll down and click Create button.

And we need to update the password in AWS Secrets Manager in Singapore to connect the Aurora Read Replica in Singapore.

The following command will update the Secrets Manager wordpressDBPassword in Singapore to the same value as the wordpressDBPassword in Ireland:

AWS_ACCOUNTID=$(aws sts get-caller-identity --query Account --output text)

aws secretsmanager update-secret \
--secret-id arn:aws:secretsmanager:ap-southeast-1:$AWS_ACCOUNTID:secret:wordpressDBPassword \
--secret-string \
$(aws secretsmanager get-secret-value \
--secret-id arn:aws:secretsmanager:eu-west-1:$AWS_ACCOUNTID:secret:wordpressDBPassword \
--region eu-west-1 \
--query "SecretString" --output text) \
--region ap-southeast-1

Update Wordpress ECS Service

  1. Go to ECS in Singapore Region, select the cluster Wordpress-Secondary-ecscluster6XXXXXXX
  2. Select the Wordpress-Secondary-wordpresssvcSXXXXX service and click Update, make sure the latest task definition is selected.
  3. Click Next 3 times and finally Update Service.

Your blog in the secondary region is now configured, it will be in Read-only mode as it is connected to the read-replica of our Aurora RDS cluster in Singapore.

Update Blog WebAsset URL with Wordpress Application Load Balancer

Find your code repo in CodeCommit and edit wordpressconfig.ts (under bookstore-WebAssets/src/wordpressconfig.ts) in Ireland region with your own domain name. Wordpress

Update http://<FQDN of your Wordpress Application Load Balancer> to

export default {
  wordpress: {
    WPURL: 'https://blog.<your subdomain>.multi-region.xyz'
  }
};

Enter any Author name and Email address, and click Commit changes. You can check the progress in CodePipeline and CodeBuild. Code

Create CloudFront Origin Group for both S3 buckets in primary and secondary regions (Optional)

Origin Failover of CloudFront distributions improves the availability of content delivered to end users. However, this is an optional configuration for the Bookstore Failover testing in the next module. Hence, you can skip it now if you have no time to configure.

Create CloudFront Origin Group (Optional)

With CloudFront’s Origin Failover capability, your content is served from your secondary origin (Singapore) if CloudFront detects that your primary origin (Ireland) is unavailable.

Click your CloudFront Distributions, and click on the "Origins and Origin Groups" tab. CloudFront

Create the second origin (in Singapore). CloudFront

Type your Orgin Domain Name with <your Singapore S3 bucket name>.s3-ap-southeast-1.amazonaws.com and select the options like the following. CloudFront

Next, create an origin group. CloudFront CloudFront automatically switches to the secondary origin when the primary origin returns specific HTTP status code failure responses. CloudFront

Completion

Congratulations! You have successfully deployed Bookstore applications in Ireland and Singapore. In the next module you will configure active/active solution using Route53.

Module 3: Configure Active-Active Route53