A basic web server that will serve templates and reload them when they are changed on disk

server.go

package main

import (
	"fmt"
	"html/template"
	"io/ioutil"
	"log"
	"net/http"
	"strings"

	"gopkg.in/fsnotify.v1"
)

var (
	templateDir     = "./webui/templates"
	staticDir       = "./webui/static"
	reloadTemplates bool
	routes          = map[string]http.HandlerFunc{
		"/": rootHandler,
	}
	t     *template.Template
	cwd   string
	pages = map[string]Page{
		"index": indexPage{
			Title: "Index",
		},
	}
)

type Page interface{}
type indexPage struct {
	Title string
}

func init() {
	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		fmt.Println(err)
	}

	// Process events
	go func() {
		for {
			select {
			case ev := <-watcher.Events:
				log.Println("event:", ev)
				reloadTemplates = true
			case err := <-watcher.Errors:
				log.Println("error:", err)
			}
		}
	}()

	err = watcher.Add(templateDir)
	if err != nil {
		fmt.Println(err)
	}
}

func parseTemplates() {
	t = template.New("templates")

	var allFiles []string

	files, err := ioutil.ReadDir(templateDir)
	if err != nil {
		fmt.Println("Error reading template dir")
	}

	for _, file := range files {
		filename := file.Name()
		if strings.HasSuffix(filename, ".html") {
			allFiles = append(allFiles, templateDir+"/"+filename)
			fmt.Println("Parsing", templateDir+"/"+filename)
		}
	}

	if err != nil {
		log.Fatal(err)
	}
	t = template.Must(template.ParseFiles(allFiles...))

}

func main() {
	parseTemplates()
	cwd = "./"
	http.HandleFunc("/static/", assetsHandler)

	for route, function := range routes {
		http.HandleFunc(route, function)
	}

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

// AssetsHandler is a static file server that serves everything in
// static directory
func assetsHandler(w http.ResponseWriter, r *http.Request) {
	http.ServeFile(w, r, staticDir+r.URL.Path)
}

// RootHandler handles the "/" connections
func rootHandler(w http.ResponseWriter, r *http.Request) {
	if reloadTemplates {
		parseTemplates()
		reloadTemplates = false
	}
	err := t.ExecuteTemplate(w, "index", pages["index"])
	if err != nil {
		fmt.Println(err)
	}
}