feat: middleware, expvar

projects/greenlight/cmd/api/main.go

@@ -3,8 +3,10 @@ package main
 import (
 	"context"
 	"database/sql"
+	"expvar"
 	"flag"
 	"os"
+	"runtime"
 	"strings"
 	"sync"
 	"time"
@@ -34,7 +36,8 @@ type config struct {
 		maxOpenConns int
 		maxIdleConns int
 		maxIdleTime  string
-	} // Add a new limiter struct containing fields for the requests-per-second and burst
+	}
+	// Add a new limiter struct containing fields for the requests-per-second and burst
 	// values, and a boolean field which we can use to enable/disable rate limiting
 	// altogether.
 	limiter struct {
@@ -138,6 +141,23 @@ func main() {
 	// established.
 	logger.PrintInfo("database connection pool established", nil)
 
+	// Publish a new "version" variable in the expvar handler containing our application
+	// version number (currently the constant "1.0.0").
+	expvar.NewString("version").Set(version)
+	expvar.Publish("goroutines", expvar.Func(func() any {
+		return runtime.NumGoroutine()
+	}))
+
+	// Publish the database connection pool statistics.
+	expvar.Publish("database", expvar.Func(func() any {
+		return db.Stats()
+	}))
+
+	// Publish the current Unix timestamp.
+	expvar.Publish("timestamp", expvar.Func(func() any {
+		return time.Now().Unix()
+	}))
+
 	app := &application{
 		config: cfg,
 		logger: logger,

projects/greenlight/cmd/api/middleware.go

@@ -247,27 +247,36 @@ func (app *application) requirePermission(code string, next http.HandlerFunc) ht
 
 func (app *application) enableCORS(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		// Add the "Vary: Origin" header.
 		w.Header().Add("Vary", "Origin")
 
-		// Get the value of the request's Origin header.
+		// Add the "Vary: Access-Control-Request-Method" header.
+		w.Header().Add("Vary", "Access-Control-Request-Method")
+
 		origin := r.Header.Get("Origin")
 
-		// Only run this if there's an Origin request header present AND at least one
-		// trusted origin is configured.
 		if origin != "" && len(app.config.cors.trustedOrigins) != 0 {
-			// Loop through the list of trusted origins, checking to see if the request
-			// origin exactly matches one of them.
 			for i := range app.config.cors.trustedOrigins {
 				if origin == app.config.cors.trustedOrigins[i] {
-					// If there is a match, then set a "Access-Control-Allow-Origin
-					// response header with the request origin as the value.
 					w.Header().Set("Access-Control-Allow-Origin", origin)
+
+					// Check if the request has the HTTP method OPTIONS and contains the
+					// "Access-Control-Request-Method" header. If it does, then we treat
+					// it as a preflight request.
+					if r.Method == http.MethodOptions && r.Header.Get("Access-Control-Request-Method") != "" {
+						// Set the necessary preflight response headers, as discussed
+						// previously.
+						w.Header().Set("Access-Control-Allow-Methods", "OPTIONS, PUT, PATCH, DELETE")
+						w.Header().Set("Access-Control-Allow-Headers", "Authorization, Content-Type")
+
+						// Write the headers along with a 200 OK status and return from
+						// the                        // the middleware with no further action.
+						w.WriteHeader(http.StatusOK)
+						return
+					}
 				}
 			}
 		}
 
-		// Call the next handler in the chain.
 		next.ServeHTTP(w, r)
 	})
 }

projects/greenlight/cmd/api/routes.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"expvar"
 	"net/http"
 
 	"github.com/julienschmidt/httprouter"
@@ -27,6 +28,8 @@ func (app *application) routes() http.Handler {
 
 	router.HandlerFunc(http.MethodPost, "/v1/tokens/authentication",
 		app.createAuthenticationTokenHandler)
+	// Register a new GET /debug/vars endpoint pointing to the expvar handler.
+	router.Handler(http.MethodGet, "/debug/vars", expvar.Handler())
 
 	return app.recoverPanic(app.enableCORS(app.rateLimit(app.authenticate(router))))
 }

projects/greenlight/cmd/examples/cors/preflight/main.go

@@ -26,7 +26,7 @@ const html = `
                     'Content-Type': 'application/json'
                 },
                 body: JSON.stringify({
-                    email: 'alice@example.com',
+                    email: 'grace@example.com',
                     password: 'pa55word'
                 })
             }).then(

projects/greenlight/docs/api/greenlight-bruno/Users/Create User.yml

@@ -13,6 +13,7 @@ http:
         "name": "Grace",
         "email": "grace@example.com",
         "password": "pa55word"
+        
       }
   auth: inherit