Serverless Integration with EKS (Lambda + EKS)

Containers and Serverless functions are not rivals, but complementary. In many modern architectures, long-running services run on Amazon EKS, while event-driven short tasks run on AWS Lambda.

Use Cases

1. File Processing: When a file is uploaded to your application on EKS, it is saved to S3. The S3 event triggers Lambda, Lambda resizes the image and reports the result to EKS.
2. Webhook Processing: You can receive webhooks from the outside world with API Gateway + Lambda, process them, and put the result in an SQS queue for EKS to consume.

Calling Lambda from EKS

To call Lambda from inside your EKS pod:

1. IRSA: Assign an IAM role with lambda:InvokeFunction permission to your pod.
2. AWS SDK: Call the function using AWS SDK inside your application.

import boto3
client = boto3.client('lambda')
response = client.invoke(FunctionName='my-function', Payload='...')

Accessing EKS from Lambda

If your Lambda function needs to access a service inside EKS (e.g., Redis or a private API):

1. VPC Config: Put Lambda in the same VPC and Private Subnets as EKS.
2. Security Group: Grant access permission to Lambda's security group from the EKS security group.

This hybrid structure is a pattern we frequently use for cost and performance optimization in AWS Consultancy projects.