When building web applications in Go the most common example is one that sets up a handler for a specific URL route (endpoint) then fires up the HTTP server to listen for requests. It looks like this.

package main

import (
    "net/http"

    "github.com/adampresley/myproject/controllers/versionController"
)

func main() {
    http.HandleFunc("/", versionController.GetVersion)
    http.ListenAndServe("0.0.0.0:8080", nil)
}

The above example shows the a basic case of listening on all IP address on port 8080, using the default ServeMux to handle routes. This is all well good, until the point where you may need more flexibility. I have reached that point.

Now I want to build a package that sets up my routes and returns a Server object that I can use in more than one project. With this I can create multiple projects that listen and serve up the same web content and write that code that serves it all up just once. To do this you need a function that can return an Http.Server structure, with which you can then listen to requests with. Here’s how that works using Gorilla Mux and the basic Go standard library.

import (
    "fmt"
    "net/http"

    "github.com/adampresley/myproject/controllers/versionController"

    "github.com/gorilla/mux"
)

func setupHttpRouter() http.Handler {
    router := mux.NewRouter()
    router.HandleFunc("/", versionController.GetVersion).Methods("GET", "OPTIONS")

    return router
}

func NewHttpServer(address string, port int) *http.Server {
    router := setupHttpRouter()
    listener := &http.Server{
        Addr:    fmt.Sprintf("%s:%d", address, port),
        Handler: router,
    }

    return listener
}

This code gives us a method named NewHttpServer which returns an HTTP server ready to serve requests on an address and port you specify. Now I can use this in my separate applications. In my case I wish to distribute a SOA web server app to be used in different front-end applications. An example of using this function would look like this.

package main

func main() {
    server := NewHttpServer("0.0.0.0", 8080)
    server.ListenAndServe()
}

Happy coding!