Is there a Go http method that converts an entire http response to a byte slice?

Question

I have been wondering if there is already a method to write all of an http/Response into a []byte? I've found responses that note that the body can be converted easily into a []byte by doing ioutil.ReadAll(response.Body), but is there an already-built solution that writes all of the information (including status codes, headers, trailers, etc.)?

The reason I ask is because I wish to transmit this entire response through a socket to a client, and the Write method of the net library requires a byte array.

Answer 1

httputil.DumpResponse is what you need (Also suggested by Adrian). The following code should help:

package main

import (
    "fmt"
    "net/http"
    "net/http/httptest"
    "net/http/httputil"
    "os"
)

func main() {
    // Create a test server
    server := httptest.NewServer(http.HandlerFunc(
        func(w http.ResponseWriter, r *http.Request) {
            // Set Header
            w.Header().Set("HEADER_KEY", "HEADER_VALUE")
            // Set Response Body
            fmt.Fprintln(w, "DUMMY_BODY")
        }))
    defer server.Close()

    // Request to the test server
    resp, err := http.Get(server.URL)
    if err != nil {
        fmt.Fprintln(os.Stderr, err)
        os.Exit(1)
    }
    defer resp.Body.Close()

    // DumpResponse takes two parameters: (resp *http.Response, body bool)
    // where resp is the pointer to the response object. And body is boolean
    // to dump body or not
    dump, err := httputil.DumpResponse(resp, true)
    if err != nil {
        fmt.Fprintln(os.Stderr, err)
        os.Exit(1)
    }
    // Dump the response ([]byte)
    fmt.Printf("%q", dump)
}

Output:

"HTTP/1.1 200 OK\r\nContent-Length: 11\r\nContent-Type: text/plain; charset=utf-8\r\n
Date: Wed, 18 Nov 2020 17:43:40 GMT\r\n
Header_key: HEADER_VALUE\r\n\r\n
DUMMY_BODY\n"