Implementation of prerender.io service in golang

prerenderingCache.go

package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"strings"
	"time"

	"gopkg.in/mgo.v2"
	"gopkg.in/mgo.v2/bson"

	"github.com/gorilla/mux"
)

//Set host in putintoCache

type cachePage struct {
	Url          string
	Content      string
	LastModified time.Time
}

var cachePages *mgo.Collection

func prerenderHandler(w http.ResponseWriter, r *http.Request) {
	requestPath := strings.TrimSuffix(r.URL.String(), "?escaped_fragment_=")
	content := serveCache(requestPath)
	fmt.Fprint(w, content)
}

func putintoCache(url string) string {
	//Request to prerender server
	host := "localhost"
	requestUrl := "http://" + host + ":3000/http://" + host + url

	//Inserting in db
	cpage := cachePage{}
	cpage.Url = url
	cpage.Content, cpage.LastModified = downloadPage(requestUrl)
	err := cachePages.Insert(&cpage)
	if err != nil {
		log.Fatal(err)
	}
	return cpage.Content
}
func downloadPage(requestUrl string) (string, time.Time) {
	resp, err := http.Get(requestUrl)
	if err != nil {
		log.Fatal(err)
	}
	defer resp.Body.Close()
	//lastmodDate := resp.Header.Get("Last-Modified")
	lastModDate := time.Now()
	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		log.Fatal(err)
	}
	return string(b), lastModDate
}
func serveCache(url string) string {
	page := cachePage{}
	err := cachePages.Find(bson.M{"url": url}).One(&page)
	cacheDurationSeconds := time.Now().Unix() - page.LastModified.Unix()
	cacheDurationDays := cacheDurationSeconds / 60 * 60 * 24
	if err != nil {
		return putintoCache(url) //if not found in db
	} else if cacheDurationDays > 1 {
		return putintoCache(url)
	} else {
		return page.Content
	}
}

func routePathHandler(w http.ResponseWriter, r *http.Request) {
	http.ServeFile(w, r, "public/index.html")
}
func hello(w http.ResponseWriter, r *http.Request) {
	fmt.Fprint(w, "hello")
}
func main() {
	session, err := mgo.Dial("localhost")
	if err != nil {
		log.Fatal(err)
	}
	cachePages = session.DB("cache").C("pages")
	r := mux.NewRouter()
	r.Queries("escaped_fragment_", "").HandlerFunc(prerenderHandler)
	//r.PathPrefix("/public").Handler(http.StripPrefix("/public", http.FileServer(http.Dir("public/"))))
	r.Path("/hello").HandlerFunc(hello)
	r.Path("/index").HandlerFunc(routePathHandler)
	r.Path("/new").HandlerFunc(routePathHandler)
	r.Path("/index/new").HandlerFunc(routePathHandler)
	r.PathPrefix("/").Handler(http.FileServer(http.Dir("public/")))
	err = http.ListenAndServe(":80", r)
	if err != nil {
		log.Fatal(err)
	}
	//When not using cache we can just redirect crawler
}