How Can I Override Conflicting Server Headers in Go Middleware?

Overriding Server Headers in Go Middleware

Background

In Go, you can use middleware to handle and modify HTTP requests and responses. However, when adding a Server middleware to control HTTP headers, you may encounter issues with multiple Server headers being present in the response if other handlers also set the Server header.

Possible Solutions

• Custom ResponseWriter Wrapper: You can define a custom ResponseWriter wrapper that sets the Server header just before all headers are written. This introduces an additional layer of indirection but effectively overrides existing Server headers.

type serverWriter struct {
    w           http.ResponseWriter
    name        string
    wroteHeader bool
}

func (s serverWriter) WriteHeader(code int) {
    if s.wroteHeader == false {
        s.w.Header().Set("Server", s.name)
        s.wroteHeader = true
    }
    s.w.WriteHeader(code)
}

func Server(h http.Handler, serverName string) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        sw := serverWriter{
            w:           w,
            name:        serverName,
            wroteHeader: false,
        }
        h.ServeHTTP(sw, r)
    })
}

• Reverse Middleware Order: You can reverse the order of your middleware, placing the Server middleware last so that it has the final say on the Server header.
• Inner-Most Middleware: Alternatively, make the Server middleware the inner-most middleware, allowing it to intercept and override other headers set by outer handlers.

Additional Notes

• The custom ResponseWriter wrapper approach introduces a new type, requiring a bit more code maintenance.
• Reversing or making the Server middleware inner-most can alter the intended flow of your middleware chain.
• The preferred solution depends on the specific requirements and complexities of your application.

The above is the detailed content of How Can I Override Conflicting Server Headers in Go Middleware?. For more information, please follow other related articles on the PHP Chinese website!