algnhsa

algnhsa

algnhsa is an AWS Lambda Go net/http server adapter.

algnhsa enables running Go web applications on AWS Lambda and API Gateway or ALB without changing the existing HTTP handlers:

package main

import (
	"fmt"
	"net/http"
	"strconv"

	"github.com/akrylysov/algnhsa"
)

func addHandler(w http.ResponseWriter, r *http.Request) {
	f, _ := strconv.Atoi(r.FormValue("first"))
	s, _ := strconv.Atoi(r.FormValue("second"))
	w.Header().Set("X-Hi", "foo")
	fmt.Fprintf(w, "%d", f+s)
}

func contextHandler(w http.ResponseWriter, r *http.Request) {
	lambdaEvent, ok := algnhsa.APIGatewayV2RequestFromContext(r.Context())
	if ok {
		fmt.Fprint(w, lambdaEvent.RequestContext.AccountID)
	}
}

func main() {
	http.HandleFunc("/add", addHandler)
	http.HandleFunc("/context", contextHandler)
	algnhsa.ListenAndServe(http.DefaultServeMux, nil)
}

Plug in a third-party web framework

Gin

package main

import (
	"net/http"

	"github.com/akrylysov/algnhsa"
	"github.com/gin-gonic/gin"
)

func main() {
	r := gin.Default()
	r.GET("/", func(c *gin.Context) {
		c.JSON(http.StatusOK, gin.H{
			"message": "hi",
		})
	})
	algnhsa.ListenAndServe(r, nil)
}

echo

package main

import (
	"net/http"

	"github.com/akrylysov/algnhsa"
	"github.com/labstack/echo/v4"
)

func main() {
	e := echo.New()
	e.GET("/", func(c echo.Context) error {
		return c.String(http.StatusOK, "hi")
	})
	algnhsa.ListenAndServe(e, nil)
}

chi

package main

import (
	"net/http"

	"github.com/akrylysov/algnhsa"
	"github.com/go-chi/chi"
)

func main() {
	r := chi.NewRouter()
	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("hi"))
	})
	algnhsa.ListenAndServe(r, nil)
}

Fiber

package main

import (
	"github.com/akrylysov/algnhsa"
	"github.com/gofiber/fiber/v2"
	"github.com/gofiber/fiber/v2/middleware/adaptor"
)

func main() {
	app := fiber.New()
	app.Get("/", func(c *fiber.Ctx) error {
		return c.SendString("Hello, World!")
	})
	algnhsa.ListenAndServe(adaptor.FiberApp(app), nil)
}

Deployment

First, build your Go application for Linux and zip it:

GOOS=linux GOARCH=amd64 go build -tags lambda.norpc -o bootstrap
zip function.zip bootstrap

When creating a new function, choose the "Provide your own bootstrap on Amazon Linux 2" runtime or "Custom runtime on Amazon Linux 2" when modifying an existing function. Make sure to use bootstrap as the executable name and as the handler name in AWS.

AWS provides plenty of ways to expose a Lambda function to the internet.

Lambda Function URL

This is the easier way to deploy your Lambda function as an HTTP endpoint. It only requires going to the "Function URL" section of the Lambda function configuration and clicking "Configure Function URL".

API Gateway

HTTP API

1. Create a new HTTP API.

2. Configure a catch-all $default route.

REST API

1. Create a new REST API.

2. In the "Resources" section create a new ANY method to handle requests to / (check "Use Lambda Proxy Integration").

3. Add a catch-all {proxy+} resource to handle requests to every other path (check "Configure as proxy resource").

ALB

1. Create a new ALB and point it to your Lambda function.

2. In the target group settings in the "Attributes" section enable "Multi value headers".