Shim is a thin layer between API Gateway integration requests via Lambda and the standard library http.Handler interface. It allows you to write plain ol' Go and run it on Lambda with minimal modifications. Bring your own router!

Shim uses dep to manage its dependencies. You can add shim to your dep project by running:

dep ensure -add github.com/iamatypeofwalrus/shim

The codebase is semantically versioned so feel free to pull the latest version with:

dep ensure -update github.com/iamatypeofwalrus/shim

For an extensive example on how shim fits in with other AWS serverless tooling like SAM Local and the Serverless Application Model (SAM) specification head over to the this example in the wiki

Make sure that proxy pass integration in API Gateway is enabled to make sure your application receives every request sent to your API Gateway endpoint.

package main

import (
  "fmt"
  "net/http"

  "github.com/aws/aws-lambda-go/lambda"

  "github.com/iamatypeofwalrus/shim"
)

func main() {
  // Create a router as normal. Any router that satisfies the http.Handler interface
  // is accepted!
  mux := http.NewServeMux()
  mux.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
    fmt.Fprint(w, "hello, world")
  })

  s := shim.New(mux)

  // Pass your router to shim and let Lambda handle the rest
  lambda.Start(s.Handle)
}

You can pull logs from various steps in the shim by passing the SetDebugLogger option. It accepts any logger that provides the Println and Printf functions a lá the standard library logger.

func main() {
  ...

  l := log.New(os.Stdout, "", log.LstdFlags)
  shim := shim.New(
    nil, // or your mux
    shim.SetDebugLogger(l)
  )

  ...
}