mrichman / samgen

Generate SAM template from OpenAPI spec

samgen

samgen will generate a skeleton Serverless Application Model (SAM) template from either an existing API Gateway REST API, or an OpenAPI 3.0 spec.

Usage

sam --rest-api-id 1a2b3c4d5e --stage dev --project-name myproject

where myproject is the name of a directory where the SAM template and related assets will be created.

Once the project is created, you will see a template.yaml file, along with a Lambda function for each of the API Gateway method requests.

For example:

AWSTemplateFormatVersion: 2010-09-09
Description: Template generated by samgen [https://github.com/mrichman/samgen]
Resources:
  CreatePetsFunction:
    Properties:
      CodeUri: functions/createPets
      Events:
        PostResource:
          Properties:
            Method: post
            Path: /createPets
          Type: Api
      FunctionName: CreatePets
      Handler: app.lambda_handler
      Runtime: python3.8
    Type: AWS::Serverless::Function
  ListPetsFunction:
    Properties:
      CodeUri: functions/listPets
      Events:
        GetResource:
          Properties:
            Method: get
            Path: /listPets
          Type: Api
      FunctionName: ListPets
      Handler: app.lambda_handler
      Runtime: python3.8
    Type: AWS::Serverless::Function
  ShowPetByIdFunction:
    Properties:
      CodeUri: functions/showPetById
      Events:
        GetResource:
          Properties:
            Method: get
            Path: /showPetById
          Type: Api
      FunctionName: ShowPetById
      Handler: app.lambda_handler
      Runtime: python3.8
    Type: AWS::Serverless::Function
Transform: AWS::Serverless-2016-10-31

Note that the actual Lambda function implementations are not imported. This is left as an exercise to the developer.

The Lambda functions are stubbed out as Python functions that look like this:

import json


def lambda_handler(event, context):
    return {
        "statusCode": 200,
        "body": json.dumps({
            "message": "hello world",
        }),
    }

TODO

• OpenAPI 3.0 spec import