chore: add server side caching

Author: martinyonatann

README.md

@@ -72,8 +72,8 @@ The DIP promotes high-level modules (e.g., use cases) to depend on abstractions
 - HTTP Server
   - [x] [Echo framework](https://echo.labstack.com/)
   - [x] Server Side Caching
-    - [ ] Cache but revalidate (Header `Cache-Control: no-cache`)
-    - [ ] Set Expiration Time (Header `Cache-Control: max-age=120`)
+    - [x] Cache but revalidate (Header `Cache-Control: no-cache`)
+    - [x] Set Expiration Time (Header `Cache-Control: max-age=120`)
   - [ ] Request ID in logger (Header `X-Request-Id: xxx`)
 - RESTful
   - [x] Create Resource (`POST` verb)

internal/app/app.go

@@ -46,6 +46,7 @@ func (app *App) Start() error {
 
 	app.Echo.Debug = app.Cfg.Server.Debug
 	app.Echo.Use(middleware.AppCors())
+	app.Echo.Use(middleware.CacheWithRevalidation)
 
 	return app.Echo.StartServer(&http.Server{
 		Addr:         fmt.Sprintf(":%s", app.Cfg.Server.RESTPort),

pkg/middleware/cors.go

@@ -0,0 +1,36 @@
+package middleware
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/labstack/echo/v4"
+	"github.com/labstack/echo/v4/middleware"
+)
+
+func AppCors() echo.MiddlewareFunc {
+	return middleware.CORSWithConfig(middleware.CORSConfig{
+		AllowOrigins: []string{"*"}, // Specify the allowed origins or use a list of allowed domains
+		AllowMethods: []string{echo.GET, echo.HEAD, echo.PUT, echo.PATCH, echo.POST, echo.DELETE},
+		AllowHeaders: []string{echo.HeaderOrigin, echo.HeaderContentType, echo.HeaderAccept, echo.HeaderAuthorization},
+	})
+}
+
+func CacheWithRevalidation(next echo.HandlerFunc) echo.HandlerFunc {
+	return func(c echo.Context) error {
+		// Call the next handler
+		err := next(c)
+
+		// Set Cache-Control header to enable caching and revalidation with a maximum age of 120 seconds
+		c.Response().Header().Set("Cache-Control", "no-cache, max-age=120, must-revalidate")
+
+		// Set Expires header to a future time to indicate the expiration time
+		expiresTime := time.Now().Add(120 * time.Second)
+		c.Response().Header().Set("Expires", expiresTime.UTC().Format(http.TimeFormat))
+
+		// Set Last-Modified header to the current time
+		c.Response().Header().Set("Last-Modified", time.Now().UTC().Format(http.TimeFormat))
+
+		return err
+	}
+}