lambtrip

The package lambtrip is an adapter that converts APIs implemented in AWS Lambda into http.RoundTripper. No need to use AWS Lambda Function URLs, AWS Gateway, ALB, etc.

Synopsis

Here is a simple API implemented in AWS Lambda:

"use strict";

exports.handler = async (event) => {
  // Lambda handler code
  return {
    body: `Hello World`,
    statusCode: 200,
  };
};

AWSTemplateFormatVersion: "2010-09-09"
Transform: AWS::Serverless-2016-10-31
Description: Lambda Function URL
Resources:
  FURLFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: src/
      Handler: app.handler
      Runtime: nodejs20.x
      Timeout: 3
      ### If you want to use Function URLs
      # FunctionUrlConfig:
      #   AuthType: AWS_IAM
      #   Cors:
      #     AllowOrigins: ["*"]

Outputs:
  FunctionURLEndpoint:
    Description: FURLFunction function name
    Value: !GetAtt FURLFunctionUrl.FunctionUrl

Use as a library

You can call the API by following code:

// initialize AWS SDK
cfg, err := config.LoadDefaultConfig(context.Background())
if err != nil {
    panic(err)
}
svc := lambda.NewFromConfig(cfg)

// register the lambda protocol
t := &http.Transport{}
t.RegisterProtocol("lambda", lambtrip.NewBufferedTransport(svc))
c := &http.Client{Transport: t}

// send a request to the lambda function
resp, err := c.Get("lambda://function-name/foo/bar")
if err != nil {
    panic(err)
}
defer resp.Body.Close()

Use function-url-local command

function-url-local is a minimum clone of AWS Lambda Function URLs.

$ go install github.com/shogo82148/lambtrip/cmd/function-url-local@latest
$ function-url-local function-name
{"time":"2024-02-05T22:28:57.781792+09:00","level":"INFO","msg":"starting the server","addr":":8080"}