Free Access Amazon Web Services SOA-C02 New Release

To route traffic based on the URL path during a transition period where both an EC2-based legacy application and a new AWS Lambda function are in use:

Use of Application Load Balancer (ALB): ALBs support advanced request routing based on the URL path, among other criteria. This capability allows the ALB to evaluate the URL path of incoming requests and route them appropriately to either the legacy EC2 instances or the Lambda function.

Path-Based Routing Rules: Configure the ALB with rules that specify which URL paths should be directed to the EC2 instances and which should be routed to the Lambda function. For example, requests to /legacy/* might go to the EC2 instances, while /new/* could be directed to the Lambda function.

Integration with Lambda: ALBs can directly invoke Lambda functions in response to HTTP requests, making them ideal for scenarios where both server-based and serverless components are used in tandem.

This setup not only facilitates a smooth transition by enabling simultaneous operation of both components but also leverages the native capabilities of ALBs to manage traffic based on application requirements effectively.

When users report that old content is still appearing on the website after modifying files in an S3 bucket used by CloudFront, creating a CloudFront invalidation is the best solution.

CloudFront Invalidation:

Invalidation is the process of removing objects from the CloudFront cache before they expire.

This ensures that the updated content is served to the users.

Creating an Invalidation:

Open the CloudFront console.

Select the distribution and go to the "Invalidations" tab.

Create a new invalidation and specify the paths of the updated files.

References:

Invalidating Files in Amazon CloudFront

To ensure that the AWS CloudFormation template works in every region, you should use the Mappings section to specify region-specific AMI IDs. This allows the template to dynamically reference the correct AMI ID based on the region where the stack is being deployed.

Steps:

Add Mappings to the Template:

Define the AMI IDs for each region in the Mappings section of the CloudFormation template.

json

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{

"Mappings": {

"RegionMap": {

"us-east-1": { "AMI": "ami-0123456789abcdef0" },

"us-west-2": { "AMI": "ami-abcdef0123456789" }

}

}

}

Reference the Mapping in the Template:

Use the Fn::FindInMap function to reference the correct AMI ID based on the region.

json

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{

"Resources": {

"MyEC2Instance": {

"Type": "AWS::EC2::Instance",

"Properties": {

"ImageId": { "Fn::FindInMap": [ "RegionMap", { "Ref": "AWS::Region" }, "AMI" ] },

}

}

}

}

Deploy the Template:

Deploy the CloudFormation stack in any region, and it will use the correct AMI ID.

AWS CloudFormation StackSets extends the capability of stacks by enabling you to create, update, or delete stacks across multiple accounts and AWS Regions

If a Lambda function is not being invoked by an Amazon EventBridge (formerly CloudWatch Events) rule, the likely issue is a missing permission. The Lambda function needs permission to be invoked by the EventBridge rule.

Steps:

Add Permission to Lambda Function:

Open the AWS Lambda console.

Select your Lambda function.

Choose "Configuration" and then "Permissions".

Under the "Resource-based policy" section, add a policy that grants EventBridge permission to invoke your function.

Example policy:

json

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{

"Version": "2012-10-17",

"Statement": [

{

"Effect": "Allow",

"Principal": {

"Service": "events.amazonaws.com"

},

"Action": "lambda:InvokeFunction",

"Resource": "arn:aws:lambda:REGION:ACCOUNT_ID:function:FUNCTION_NAME",

"Condition": {

"ArnLike": {

"AWS:SourceArn": "arn:aws:events:REGION:ACCOUNT_ID:rule/RULE_NAME"

}

}

}

]

}

Verify the EventBridge Rule:

Open the Amazon EventBridge console.

Select the rule that targets your Lambda function.

Ensure that the rule is correctly configured to match events and the target is your Lambda function.

References:

AWS Lambda Permissions Model

Amazon EventBridge Rules