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package main
import (
"CommentsEngine/redisc"
"encoding/json"
"errors"
"fmt"
"github.com/gorilla/handlers"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/redis/go-redis/v9"
"io"
"log"
"net/http"
"os"
)
func getenv(key, fallback string) string {
value := os.Getenv(key)
if len(value) == 0 {
return fallback
}
return value
}
var (
httpHits = promauto.NewCounterVec(prometheus.CounterOpts{
Name: "comments_engine_http_hits_total",
Help: "The total number of hits on a given route",
}, []string{"route", "method"})
commentsReceived = promauto.NewCounter(prometheus.CounterOpts{
Name: "comments_engine_comments_received_total",
Help: "The total number of comments received",
})
errorsSent = promauto.NewCounter(prometheus.CounterOpts{
Name: "comments_interactor_errors_sent_total",
Help: "The total number of errors returned",
})
)
func getRoot(w http.ResponseWriter, r *http.Request) {
httpHits.With(prometheus.Labels{"route": "/", "method": r.Method}).Inc()
io.WriteString(w, "CommentsEngine answering here !\n")
}
func sendError(w http.ResponseWriter, err error, additionalInfo string) {
errorsSent.Inc()
w.WriteHeader(http.StatusInternalServerError)
resp := make(map[string]string)
resp["message"] = fmt.Sprint(err)
resp["additionalInfo"] = additionalInfo
jsonResp, err := json.Marshal(resp)
if err != nil {
log.Fatalf("Error happened in JSON marshal. Err: %s", err)
}
w.Write(jsonResp)
}
func sendMessage(w http.ResponseWriter, message string) {
commentsReceived.Inc()
resp := make(map[string]string)
resp["message"] = message
jsonResp, err := json.Marshal(resp)
if err != nil {
log.Fatalf("Error happened in JSON marshal. Err: %s", err)
}
w.Write(jsonResp)
}
func getLatestComments(w http.ResponseWriter, r *http.Request) {
httpHits.With(prometheus.Labels{"route": "/latest", "method": r.Method}).Inc()
w.Header().Set("Content-Type", "application/json")
messages, err := redisc.GetLatestComments()
if err == nil {
io.WriteString(w, messages)
} else {
sendError(w, err, "Maybe there is a problem with redis backend ?")
}
}
type Comment struct {
Comment string `json:"comment"`
}
func sendComment(w http.ResponseWriter, r *http.Request) {
httpHits.With(prometheus.Labels{"route": "/comment", "method": r.Method}).Inc()
w.Header().Set("Content-Type", "application/json")
if r.Method != http.MethodPost {
sendError(w, errors.New("POST not used"), "HTTP method was not POST")
return
}
comment := &Comment{}
err := json.NewDecoder(r.Body).Decode(comment)
if err != nil {
sendError(w, err, "The data sent was likely incorrect")
return
}
_, err = redisc.StoreComment(comment.Comment)
if err != nil {
sendError(w, err, "Problem with redis maybe ?")
return
}
sendMessage(w, "stored !")
}
func main() {
http.HandleFunc("/", getRoot)
http.HandleFunc("/latest", getLatestComments)
http.HandleFunc("/comment", sendComment)
http.Handle("/metrics", promhttp.Handler())
redisc.Client = redis.NewClient(&redis.Options{
Addr: getenv("REDIS_ENDPOINT", "localhost:6379"),
Password: "", // no password set
DB: 0, // use default DB
})
listeningHostPort := getenv("HOST", "127.0.0.1") + ":" + getenv("PORT", "8000")
fmt.Printf("Starting the server on %s\n", listeningHostPort)
err := http.ListenAndServe(listeningHostPort, handlers.LoggingHandler(os.Stdout, http.DefaultServeMux))
if errors.Is(err, http.ErrServerClosed) {
fmt.Printf("server closed\n")
} else if err != nil {
fmt.Printf("error starting server: %s\n", err)
os.Exit(1)
}
}
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