Serverless Load Balancer

A sample that shows how to combine a load balancer with (vpc/subnet configuration) with a lambda.

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serverless framework sample that shows how to deploy a load balancer (with vpc/subnet configuration) connected to a lambda in aws.

  • creates a LoadBalancer, HTTP Listener and Lambda
  • links the Listener and Lambda
  • stores the LoadBalancerDNSName (url) in ParameterStore

This feature has been introduced in v 1.45 and extended in 1.46 serverless framework

when to use load balancer instead of api gateway ?

Install Requirements

npm install serverless -g
npm install

Modify Config

Modify the file /config/serverless.config.yml

    VPC_ID: 'vpc-xxxxxxxxx'
    SUBNET_ID_A: "subnet-xxxxxxxxx"
    SUBNET_ID_B: "subnet-xxxxxxxxx"
    SUBNET_ID_C: "subnet-xxxxxxxxx"
    SCHEME: "internet-facing" or "internal" # load balancer scheme - 

Deploy solution

sls deploy


  1. Execute info to get load balancer url
sls info -v

you should get the full output containing the load balancer url.

Stack Outputs
HandlerLambdaFunctionQualifiedArn: arn:aws:lambda:eu-central-1:368555349508:function:serverless-load-balancer-dev-handler:1
ServerlessDeploymentBucketName: serverless-load-balancer-serverlessdeploymentbuck-16pgpyls1225e
  1. Paste the LoadBalancerDNSName Value into your browser or execute postman to set a GET statement against the URL.

Expected Response:

    Successfully executed lambda call via loadbalancer

Additional things to know

  • This sample does not care if the lambda and the load balancer are both in a vpc. It could be mixed in anyway dependent of the use case

  • The load balancer url will be stored as Parameter in Parameter store. This helps to reference the loadbalancer url easily tool-independent in other stacks.