Multiple Lambdas with a single API Gateway

serverless-api-gateway.yml

# serverless-api-gateway.yml
service: central-api-gateway

provider:
  name: aws
  runtime: nodejs14.x
  stage: dev
  region: sua-região

resources:
  Resources:
    MySharedApiGateway:
      Type: AWS::ApiGateway::RestApi
      Properties:
        Name: SharedAPIGateway
        Description: Um API Gateway central para todos os microserviços.

serverless-microservice.yml

# serverless-microservice.yml
service: microservice-nome

provider:
  name: aws
  runtime: nodejs14.x
  stage: dev
  region: sua-região
  apiGateway:
    restApiId: "ID_DO_SEU_API_GATEWAY_CENTRAL"
    restApiRootResourceId: "ID_DO_RECURSO_RAIZ_SE_NECESSÁRIO" # Opcional

functions:
  minhaFuncao:
    handler: handler.minhaFuncao
    events:
      - http:
          path: caminho/da/funcao
          method: get