aws-lambda-go-http-adapter

README

aws-lambda-go-http-adapter

Simple HTTP adapter for AWS Lambda

Builtin support for these event formats:

• AWS Lambda Function URL (both normal and streaming)
• API Gateway (v1)
• API Gateway (v2)
• Application Load Balancer

Builtin support for these HTTP frameworks:

• net/http
• Echo
• Fiber

Usage

Creating the Adapter

net/http

package main

import (
	"github.com/its-felix/aws-lambda-go-http-adapter/adapter"
	"net/http"
)

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/ping", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte("pong"))
	})
	
	adapter := adapter.NewVanillaAdapter(mux)
}

Echo

package main

import (
	"github.com/labstack/echo/v4"
	"github.com/its-felix/aws-lambda-go-http-adapter/adapter"
	"net/http"
)

func main() {
	e := echo.New()
	e.Add("GET", "/ping", func(c echo.Context) error {
		return c.String(200, "pong")
	})
	
	adapter := adapter.NewEchoAdapter(e)
}

Fiber

package main

import (
	"github.com/gofiber/fiber/v2"
	"github.com/its-felix/aws-lambda-go-http-adapter/adapter"
)

func main() {
	app := fiber.New()
	app.Get("/ping", func(ctx *fiber.Ctx) error {
		return ctx.SendString("pong")
	})

	adapter := adapter.NewFiberAdapter(app)
}

Creating the Handler

API Gateway V1

package main

import (
	"github.com/aws/aws-lambda-go/lambda"
	"github.com/its-felix/aws-lambda-go-http-adapter/handler"
)

func main() {
	adapter := [...] // see above
	h := handler.NewAPIGatewayV1Handler(adapter)
	
	lambda.Start(h)
}

API Gateway V2

package main

import (
	"github.com/aws/aws-lambda-go/lambda"
	"github.com/its-felix/aws-lambda-go-http-adapter/handler"
)

func main() {
	adapter := [...] // see above
	h := handler.NewAPIGatewayV2Handler(adapter)
	
	lambda.Start(h)
}

Lambda Function URL (normal)

package main

import (
	"github.com/aws/aws-lambda-go/lambda"
	"github.com/its-felix/aws-lambda-go-http-adapter/handler"
)

func main() {
	adapter := [...] // see above
	h := handler.NewFunctionURLHandler(adapter)
	
	lambda.Start(h)
}

Lambda Function URL (streaming)

(read the additional notes about streaming below)

package main

import (
	"github.com/aws/aws-lambda-go/lambda"
	"github.com/its-felix/aws-lambda-go-http-adapter/handler"
)

func main() {
	adapter := [...] // see above
	h := handler.NewFunctionURLStreamingHandler(adapter)
	
	lambda.Start(h)
}

Accessing the source event

Fiber

package main

import (
	"github.com/aws/aws-lambda-go/events"
	"github.com/gofiber/fiber/v2"
	"github.com/its-felix/aws-lambda-go-http-adapter/adapter"
)

func main() {
	app := fiber.New()
	app.Get("/ping", func(ctx *fiber.Ctx) error {
		event := adapter.GetSourceEventFiber(ctx)
		switch event := event.(type) {
		case events.APIGatewayProxyRequest:
			// do something
		case events.APIGatewayV2HTTPRequest:
			// do something
		case events.LambdaFunctionURLRequest:
			// do something
		}
		
		return ctx.SendString("pong")
	})
}

Others

package main

import (
	"github.com/aws/aws-lambda-go/events"
	"github.com/its-felix/aws-lambda-go-http-adapter/handler"
	"net/http"
)

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/ping", func(w http.ResponseWriter, r *http.Request) {
		event := handler.GetSourceEvent(r.Context())
		switch event := event.(type) {
		case events.APIGatewayProxyRequest:
			// do something
		case events.APIGatewayV2HTTPRequest:
			// do something
		case events.LambdaFunctionURLRequest:
			// do something
		}
		
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte("pong"))
	})
}

Handle panics

To handle panics, first create the handler as described above. You can then wrap the handler to handle panics like so:

package main

import (
	"context"
	"github.com/aws/aws-lambda-go/lambda"
	"github.com/aws/aws-lambda-go/events"
	"github.com/its-felix/aws-lambda-go-http-adapter/handler"
)

func main() {
	adapter := [...] // see above
	h := [...] // see above
	h = handler.WrapWithRecover(h, func(ctx context.Context, event events.APIGatewayV2HTTPRequest, panicValue any) (events.APIGatewayV2HTTPResponse, error) {
		return events.APIGatewayV2HTTPResponse{
			StatusCode:        500,
			Headers:           make(map[string]string),
			Body:              fmt.Sprintf("Unexpected error: %v", panicValue),
		}, nil
	})
	
	lambda.Start(h)
}

Extending for other lambda event formats:

Have a look at the existing event handlers:

• API Gateway V1
• API Gateway V2
• Lambda Function URL

Extending for other frameworks

Have a look at the existing adapters:

• net/http
• Echo
• Fiber

Build Tags

You can opt-in to enable partial build by using the build-tag lambdahttpadapter.partial.

Once this build-tag is present, the following build-tags are available:

• lambdahttpadapter.vanilla (enables the vanilla adapter)
• lambdahttpadapter.echo (enables the echo adapter)
• lambdahttpadapter.fiber (enables the fiber adapter)
• lambdahttpadapter.apigwv1 (enables API Gateway V1 handler)
• lambdahttpadapter.apigwv2 (enables API Gateway V2 handler)
• lambdahttpadapter.functionurl (enables Lambda Function URL handler)
• lambdahttpadapter.alb (enables Application Load Balancer handler)

Also note that Lambda Function URL in Streaming-Mode requires the following build-tag to be set:

• lambda.norpc

Note about Lambda streaming

Response streaming is currently not supported for the fiber adapter. The code will work, but the response body will only be sent downstream as soon as the request was processed completely.

This is because there seems to be no way in fasthttp to provide a io.Writer to be populated while the request is being processed.