@@ -49,10 +49,7 @@ func Handler(fileSystem fs.FS, options *Options) (http.Handler, error) {
4949}
5050
5151// Fallback to static file server for non-HTML files
52- // Non-HTML files don't have special routing rules, so we can just leverage
53- // the built-in http.FileServer for it.
54- fileHandler := http .FileServer (http .FS (fileSystem ))
55- router .NotFound (fileHandler .ServeHTTP )
52+ router .NotFound (FileHandler (fileSystem ))
5653
5754// Finally, if there is a 404.html available, serve that
5855err = register404 (fileSystem ,router ,* options )
@@ -64,6 +61,31 @@ func Handler(fileSystem fs.FS, options *Options) (http.Handler, error) {
6461return router ,nil
6562}
6663
64+ // FileHandler serves static content, additionally adding immutable
65+ // cache-control headers for Next.js content
66+ func FileHandler (fileSystem fs.FS )func (writer http.ResponseWriter ,request * http.Request ) {
67+ // Non-HTML files don't have special routing rules, so we can just leverage
68+ // the built-in http.FileServer for it.
69+ fileHandler := http .FileServer (http .FS (fileSystem ))
70+
71+ return func (writer http.ResponseWriter ,request * http.Request ) {
72+ // From the Next.js documentation:
73+ //
74+ // "Caching improves response times and reduces the number
75+ // of requests to external services. Next.js automatically
76+ // adds caching headers to immutable assets served from
77+ // /_next/static including JavaScript, CSS, static images,
78+ // and other media."
79+ //
80+ // See: https://nextjs.org/docs/going-to-production
81+ if strings .HasPrefix (request .URL .Path ,"/_next/static/" ) {
82+ writer .Header ().Add ("Cache-Control" ,"public, max-age=31536000, immutable" )
83+ }
84+
85+ fileHandler .ServeHTTP (writer ,request )
86+ }
87+ }
88+
6789// registerRoutes recursively traverses the file-system, building routes
6890// as appropriate for respecting NextJS dynamic rules.
6991func registerRoutes (rtr chi.Router ,fileSystem fs.FS ,options Options )error {
