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/shimYou'll want to use the proxy pass integration with API Gateway to make sure your application receives every request sent to your API Gateway endpoint.
# Here we're using the SAM specification to define our function
#
# Note: You need both the Root AND the Greedy event in order to capture all
# events sent to your web app.
YourFunction:
Type: AWS::Serverless::Function
Properties:
Handler: main
Runtime: go1.x
Role: ...
Events:
ProxyApiRoot:
Type: Api
Properties:
Path: /
Method: ANY
ProxyApiGreedy:
Type: Api
Properties:
Path: /{proxy+}
Method: ANY
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)
}package main
import (
"fmt"
"net/http"
"github.com/aws/aws-lambda-go/lambda"
"github.com/iamatypeofwalrus/shim"
)
func main() {
// Shim works with the http.DefaultServeMux. Create routes and handlers against the router normal.
http.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
fmt.Fprint(w, "hello, world")
})
// Simply pass nil to shim to use the http.DefaultServeMux
s := shim.New(nil)
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)
)
lambda.Start(shim.Handle)
}