feat: Add authentication middleware.

internal/middleware/authentication.go

@@ -0,0 +1,64 @@
+// Package middleware is to define the different middleware for the http server.
+package middleware
+
+import (
+	"github.com/gowizzard/mobyspulse/internal/write"
+	"net/http"
+	"os"
+	"reflect"
+)
+
+// config is to define the configuration for the basic auth.
+type config struct {
+	Username string
+	Password string
+	Ok       bool
+}
+
+// environment is to define the configuration for the basic auth.
+var (
+	environment config
+)
+
+// init is to initialize the basic auth configuration. If the environment variables BASIC_AUTH_USERNAME and
+// BASIC_AUTH_PASSWORD are set, then the basic auth is enabled. If the environment variables are not set, then the
+// basic auth is disabled.
+func init() {
+
+	environment.Username, environment.Ok = os.LookupEnv("BASIC_AUTH_USERNAME")
+	environment.Password, environment.Ok = os.LookupEnv("BASIC_AUTH_PASSWORD")
+
+	if environment.Ok {
+		write.Logger.Info("Basic auth is enabled.")
+	}
+
+}
+
+// Authentication is to authenticate the request with basic auth. If the environment variables BASIC_AUTH_USERNAME and
+// BASIC_AUTH_PASSWORD are set, then the request will be authenticated with basic auth. If the environment variables are
+// not set, then the request will be passed to the next handler.
+func Authentication(next http.HandlerFunc) http.HandlerFunc {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+
+		if environment.Ok {
+
+			username, password, ok := r.BasicAuth()
+			if ok {
+
+				if reflect.DeepEqual(environment.Username, username) && reflect.DeepEqual(environment.Password, password) {
+					next.ServeHTTP(w, r)
+					return
+				}
+
+			}
+
+			w.Header().Set("WWW-Authenticate", `Basic realm="Restricted"`)
+			http.Error(w, "Unauthorized", http.StatusUnauthorized)
+			return
+
+		}
+
+		next.ServeHTTP(w, r)
+
+	})
+}

internal/router/handler.go

@@ -3,6 +3,7 @@ package router
 
 import (
 	"github.com/gowizzard/mobyspulse/internal/handler"
+	"github.com/gowizzard/mobyspulse/internal/middleware"
 	"github.com/gowizzard/mobyspulse/internal/redirect"
 	"net/http"
 )
@@ -11,5 +12,5 @@ import (
 func Handler(mux *http.ServeMux) {
 	mux.HandleFunc(http.MethodGet+" /", redirect.Metrics)
 	mux.HandleFunc(http.MethodGet+" /favicon.ico", handler.Favicon)
-	mux.HandleFunc(http.MethodGet+" /metrics", handler.Metrics)
+	mux.HandleFunc(http.MethodGet+" /metrics", middleware.Authentication(handler.Metrics))
 }