Amazon Web Services Updated SOA-C02 Exam Questions and Answers by ciaran

When attempting to deploy a CloudFormation template from one region (us-west-2) to another (eu-west-1), the deployment might fail due to region-specific resources and services.

Amazon Machine Image (AMI) Availability:

AMIs are region-specific. If the template references an AMI that is only available in us-west-2 and not in eu-west-1, the stack will fail to deploy in eu-west-1.

To resolve this, identify the AMI used in us-west-2 and find or create a similar AMI in eu-west-1.

Service Availability:

Some AWS services are not available in all regions. If the template includes resources or services that are not available in eu-west-1, the stack will fail.

Check the AWS Regional Services List to ensure all services and resource types in the template are available in eu-west-1.

References:

Copy an AMI

AWS Regional Services List

A stack policy is used to protect specific resources within a CloudFormation stack from being unintentionally updated or deleted. By using a stack policy, you can explicitly deny updates to critical resources while allowing updates to other parts of the stack.

Create a Stack Policy:

Define a JSON stack policy that includes an explicit allow for all resources and an explicit deny for the protected resources. For example:

json

Copy code

{

"Statement": [

{

"Effect": "Allow",

"Action": "Update:*",

"Principal": "*",

"Resource": "*"

},

{

"Effect": "Deny",

"Action": "Update:*",

"Principal": "*",

"Resource": "arn:aws:cloudformation:region:account-id:stack/stack-name/protected-resource"

}

]

}

Replace region, account-id, stack-name, and protected-resource with the appropriate values.

Apply the Stack Policy:

Navigate to the CloudFormation console.

Select the stack you want to protect.

Choose "Stack actions" and then "Edit stack policy".

Paste the stack policy JSON and save the policy.

Perform Stack Updates:

When performing stack updates, the stack policy will enforce the rules specified, preventing accidental updates to the protected resources.

Review and Adjust:

Periodically review the stack policy to ensure it still meets the needs of the organization and update it as necessary.

References:

AWS CloudFormation Stack Policies

Creating and Applying a Stack Policy

 Create an IAM role with the CloudWatchAgentServerPolicy:

This policy grants the necessary permissions for the CloudWatch agent to collect and send metrics.

Steps:

Go to the AWS Management Console.

Navigate to IAM and create a new role.

Choose "EC2" as the trusted entity.

Attach the "CloudWatchAgentServerPolicy" managed policy to the role.

Attach this IAM role to your EC2 instances.

To optimize the routing of requests to the application for users in different geographic locations, use Amazon Route 53's latency-based routing:

Latency Routing Policy: Modify the Route 53 DNS settings for app.anycompany.com by changing the routing policy to latency. This policy routes user requests to the server that has the lowest latency relative to the user's location.

Configure Latency Records: Create latency records for each ALB—one for the ALB in us-west-2 and another for the new ALB in ap-southeast-2. Route 53 will automatically direct traffic to the endpoint that provides the lowest latency connection to the user.

Seamless User Experience: By using latency routing, the URL remains the same (app.anycompany.com), but the backend service location varies based on which endpoint is likely to respond the fastest. This setup provides a seamless experience for users, reducing latency without requiring any changes to how they access the application.

This method leverages Route 53's advanced DNS capabilities to ensure optimal performance and user experience by dynamically routing traffic based on geographic latency considerations.