Cache static files

[maciej-jezierski]

Hi all,

recently I am reading the caching solution and came to etag HTTP header and cache policy. I made this a sample implementation, which might be not ideal, but enable cache against the static assets. Maybe it could be converted to some middleware plugin. It allows the page to be faster and save brand switch.

e.Use(func(next echo.HandlerFunc) echo.HandlerFunc {
		return func(c echo.Context) error {
			if strings.HasSuffix(c.Request().RequestURI, ".js") || strings.HasPrefix(c.Request().RequestURI, ".ico") || strings.HasPrefix(c.Request().RequestURI, ".css") || strings.HasPrefix(c.Request().RequestURI, ".png") {
				s := strings.Split(c.Request().RequestURI, "/")
				etag := s[len(s)-1]

				c.Response().Header().Set("Etag", etag)
				c.Response().Header().Set("Cache-Control", "max-age=2592000")
				if match := c.Request().Header.Get("If-None-Match"); match != "" {
					if strings.Contains(match, etag) {
						return c.NoContent(http.StatusNotModified)
					}
				}
			}
			return next(c)
		}
	})

Some reading: https://web.dev/uses-long-cache-ttl/?utm_source=lighthouse&utm_medium=unknown

[aldas]

Do you know much of this is in standard library and what is not? Looking at http.serveContent implementation it mentions ETag and handles other headers

// handles If-Match, If-Unmodified-Since, If-None-Match, If-Modified-Since,

Static middleware and c.File() uses http.serveContent to serve files.

[maciej-jezierski]

From what I see in the http implementation it's doing a lookup for ETag but never serves it as well it never set cache modified header. Maybe step with returning "not modified" response is obsolete, but in my case, I am serving sometimes files by c.GET and it's an additional benefit for me to fallback to cache without hitting database.