conductor

Conductor is an HTTP component library.

Conductor provides an easy way to define a sequence of middleware components that is applied to handlers when executed.

Create a new Conductor instance and add components:

c := conductor.New()
c.Use(myMiddlwareHandler)

Components are handlers that wrap another handler. Any func with the following signature is a Component:

func(http.Handler) http.Handler

A Conductor can return a handler for any http.Handler that applies the entire component sequence calling the input http.Handler last. There is also a variation that accepts a http.HandlerFunc and wraps it.

mux := http.NewServeMux()
mux.Handle("/posts", c.Handler(postsHandler))
mux.Handle("/comments", c.HandlerFunc(commentsFn))

Usage

This is an example of a simple web app using conductor. For more detailed example, see example_test.go file.

package main

import (
	"fmt"
	"html"
	"log"
	"net/http"

	"github.com/ascarter/conductor"
)

func logRequest(h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		log.Printf("starting request %s", r.URL.Path)
		h.ServeHTTP(w, r)
		log.Println("completed request %s", r.URL.Path)
	})
}

func helloHandler(w http.ResponseWriter, r *http.Request) {
	log.Println("Running hello handler")
	fmt.Fprintf(w, "Hello, %q", html.EscapeString(r.URL.Path))
}

func goodbyeHandler(w http.ResponseWriter, r *http.Request) {
	log.Println("Running goodbye handler")
	fmt.Fprintf(w, "Goodbye, %q", html.EscapeString(r.URL.Path))
}

func main() {
	// Define middleware
	c := conductor.New()
	c.Use(logRequest)

	// Add routes
	http.Handle("/hello", c.HandlerFunc(helloHandler))
	http.Handle("/goodbye", c.HandlerFunc(goodbyeHandler))

	// Start server
	log.Fatal(http.ListenAndServe(":8080", nil))
}

Components

The following are components that work with conductor. In general, many existing handlers use the Component signature or can easily be wrapped to work.

Component	Author	Description
cors	Oliver Poitrey	Cross Origin Resource Sharing (CORS) support
requestid	Andrew Carter	Add UUID request id
requestlog	Andrew Carter	Log start and end of each request

References

conductor was influenced by the following:

• Joe Shaw - Revisiting context and http.Handler for Go 1.7
• alice by justinas
• Mat Ryer - The http.Handler wrapper technique in golang