Facing issue after deploying Go app on Heroku - heroku

Question

I have deployed the Go App on Heroku but on hitting the url.. its not giving proper response. The Heroku logs looks something like this :
2015-06-27T10:43:06.839094+00:00 heroku[web.1]: Starting process with command `FlickrImage`
2015-06-27T10:43:08.998400+00:00 heroku[web.1]: State changed from starting to crashed
2015-06-27T10:43:08.998400+00:00 heroku[web.1]: State changed from crashed to starting
2015-06-27T10:43:08.985737+00:00 heroku[web.1]: Process exited with status 0
2015-06-27T10:43:10.795684+00:00 heroku[web.1]: Starting process with command `FlickrImage`
2015-06-27T10:43:13.837301+00:00 heroku[web.1]: Process exited with status 0
2015-06-27T10:43:13.850141+00:00 heroku[web.1]: State changed from starting to crashed
2015-06-27T10:44:41.914412+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/Index" host=morning-ridge-1365.herokuapp.com request_id=89d2e794-a725-4ddf-b437-dbcbd988428c fwd="202.12.83.44" dyno= connect= service= status=503 bytes=
FlickrImage is my go file and I have created a Procfile which contains "web: FlickrImage"
EDIT :
FlickrImageServer Code :
package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"log"
"net/http"
"os"
"reflect"
"strconv"
"strings"
"github.com/gorilla/mux"
"gopkg.in/mgo.v2"
"gopkg.in/mgo.v2/bson"
)
type imageLinks struct {
Link string `bson:"link"`
Upvote int `bson:"upvote"`
Downvote int `bson:"downvote"`
}
type Result struct {
Photos struct {
Page int `json: "page"`
Pages int `json: "pages"`
PerPage int `json: "perpage"`
Total string `json: "total"`
Photo []struct {
Id string `json: "id"`
Owner string `json: "owner"`
Secret string `json: "secret"`
Server string `json: "server"`
Farm int `json: "farm"`
Title string `json: "title"`
IsPublic int `json: "ispublic"`
IsFriend int `json: "isfriend"`
IsFamily int `json: "isfamily`
} `json: "photo"`
} `json: "photos"`
Stat string `json: "stat"`
}
func main() {
router := mux.NewRouter().StrictSlash(true)
router.HandleFunc("/Index", Index)
router.HandleFunc("/UpVote", UpVoteRoute)
router.HandleFunc("/DownVote", DownVoteRoute)
log.Fatal(http.ListenAndServe(":8080", router))
}
func UpVoteRoute(w http.ResponseWriter, r *http.Request) {
link := r.URL.Query().Get("imagelink")
w.Header().Set("Content-Type", "application/json")
session, err := mgo.Dial("mongodb://<user>:<password>#ds061631.mongolab.com:61631/flickrimagedb")
if err != nil {
fmt.Printf("%s", err)
os.Exit(1)
}
defer session.Close()
session.SetMode(mgo.Monotonic, true)
c := session.DB("flickrimagedb").C("image_links_votes")
err = c.Update(bson.M{"link": link}, bson.M{"$inc": bson.M{"upvote": 1}})
if err != nil {
fmt.Printf("Can't update document %v\n", err)
os.Exit(1)
}
}
func DownVoteRoute(w http.ResponseWriter, r *http.Request) {
link := r.URL.Query().Get("imagelink")
w.Header().Set("Content-Type", "application/json")
session, err := mgo.Dial("mongodb://*********:*******#ds061631.mongolab.com:61631/flickrimagedb")
if err != nil {
fmt.Printf("%s", err)
os.Exit(1)
}
defer session.Close()
session.SetMode(mgo.Monotonic, true)
c := session.DB("flickrimagedb").C("image_links_votes")
err = c.Update(bson.M{"link": link}, bson.M{"$inc": bson.M{"downvote": 1}})
if err != nil {
fmt.Printf("Can't update document %v\n", err)
os.Exit(1)
}
}
func Index(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "application/json")
session, err := mgo.Dial("mongodb://*********:*********#ds061631.mongolab.com:61631/flickrimagedb")
if err != nil {
fmt.Printf("%s", err)
os.Exit(1)
}
defer session.Close()
session.SetMode(mgo.Monotonic, true)
c := session.DB("flickrimagedb").C("image_links_votes")
checkResult := &imageLinks{}
// Create a slice to begin with
myType := reflect.TypeOf(checkResult)
slice := reflect.MakeSlice(reflect.SliceOf(myType), 10, 10)
// Create a pointer to a slice value and set it to the slice
x := reflect.New(slice.Type())
x.Elem().Set(slice)
err = c.Find(bson.M{}).All(x.Interface())
if err != nil {
response, err := json.Marshal(x.Interface())
if err != nil {
fmt.Printf("%s", err)
os.Exit(2)
}
fmt.Fprintf(w, string(response))
} else {
url := "https://api.flickr.com/services/rest/?method=flickr.photos.search&api_key=*****************************&text=cute+puppies&per_page=12&format=json&nojsoncallback=1"
res, err := http.Get(url)
if err != nil {
fmt.Printf("%s", err)
os.Exit(3)
}
body, err := ioutil.ReadAll(res.Body)
if err != nil {
fmt.Printf("%s", err)
os.Exit(4)
}
jsonData := &Result{}
err = json.Unmarshal(body, jsonData)
for value := range jsonData.Photos.Photo {
s1 := []string{"https://farm", ".staticflickr.com/"}
s2 := []string{strings.Join(s1, strconv.Itoa(jsonData.Photos.Photo[value].Farm)), "/"}
s3 := []string{strings.Join(s2, jsonData.Photos.Photo[value].Server), "_"}
s4 := []string{strings.Join(s3, jsonData.Photos.Photo[value].Id), ".jpg"}
s := strings.Join(s4, jsonData.Photos.Photo[value].Secret)
singleReuslt := imageLinks{}
err = c.Find(bson.M{"link": s}).One(&singleReuslt)
if err != nil {
err = c.Insert(&imageLinks{Link: s, Upvote: 0, Downvote: 0})
if err != nil {
fmt.Printf("%s", err)
os.Exit(5)
}
}
}
allResult := &imageLinks{}
// Create a slice to begin with
myType := reflect.TypeOf(allResult)
slice := reflect.MakeSlice(reflect.SliceOf(myType), 10, 10)
// Create a pointer to a slice value and set it to the slice
x := reflect.New(slice.Type())
x.Elem().Set(slice)
err = c.Find(bson.M{}).All(x.Interface())
response, err := json.Marshal(x.Interface())
if err != nil {
fmt.Printf("%s", err)
os.Exit(6)
}
fmt.Fprintf(w, string(response))
}
}
Any help would be appreciated

Answer 1

Heroku dynos dynamically assign a port. It's likely your application is crashing because it can't bind to port 8080.
Change this line:
log.Fatal(http.ListenAndServe(":8080", router))
... to this:
port := ":" + os.Getenv("PORT")
log.Fatal(http.ListenAndServe(port, router))