Trigger lambda function using AWS Elastic load balance

serverless.yml

service: sample-lambda-alb

provider:
  name: aws
  runtime: nodejs14.x
  stage: ${opt:stage, 'dev'}
  region: ${opt:region, 'us-west-2'}
  profile: crazy
  alb:
    targetGroupPrefix: tg-${opt:stage, 'dev'}- # this is the name for the target group

custom:
  alb: # If you are using the same ALB ARN you must set uniq priority
    priority:
      prod: 1
      dev: 2

functions:
  validate-user:
    description: "Example lambda using elastic load balance"
    handler: handler.producer
    name: sample-lambda-alb-${opt:stage, 'dev'}
    timeout: 900 # This is set to 15min
    memorySize: 128
    events:
      - alb:
          listenerArn: ALB_LISTENER_ARN
          priority: ${self:custom.alb.priority.${opt:stage, self:provider.stage}}
          method: GET
          conditions:
            path: /validate-user/${opt:stage, 'dev'} # enable both url /validate-user/dev and /validate-user/dev

You will need to create an ALB type application and also create a listener without target, after that just copy the ARN and replace ir for ALB_LISTENER_ARN