feat: allow DERP headers to be set (#6572)

* feat: allow DERP headers to be set

* chore: remove custom flag

* Clone DERP header on client create

* Adjust to use interface to cast headers

---------

Co-authored-by: Kyle Carberry <kyle@carberry.com>

cli/root.go

@@ -334,14 +334,14 @@ func createUnauthenticatedClient(cmd *cobra.Command, serverURL *url.URL) (*coder
 	}
 	transport := &headerTransport{
 		transport: http.DefaultTransport,
-		headers:   map[string]string{},
+		header:    http.Header{},
 	}
 	for _, header := range headers {
 		parts := strings.SplitN(header, "=", 2)
 		if len(parts) < 2 {
 			return nil, xerrors.Errorf("split header %q had less than two parts", header)
 		}
-		transport.headers[parts[0]] = parts[1]
+		transport.header.Add(parts[0], parts[1])
 	}
 	client.HTTPClient.Transport = transport
 	return client, nil
@@ -655,12 +655,18 @@ func checkWarnings(cmd *cobra.Command, client *codersdk.Client) error {
 
 type headerTransport struct {
 	transport http.RoundTripper
-	headers   map[string]string
+	header    http.Header
+}
+
+func (h *headerTransport) Header() http.Header {
+	return h.header.Clone()
 }
 
 func (h *headerTransport) RoundTrip(req *http.Request) (*http.Response, error) {
-	for k, v := range h.headers {
-		req.Header.Add(k, v)
+	for k, v := range h.header {
+		for _, vv := range v {
+			req.Header.Add(k, vv)
+		}
 	}
 	return h.transport.RoundTrip(req)
 }

cli/scaletest.go

@@ -330,8 +330,8 @@ func scaletestCleanup() *cobra.Command {
 			client.HTTPClient = &http.Client{
 				Transport: &headerTransport{
 					transport: http.DefaultTransport,
-					headers: map[string]string{
-						codersdk.BypassRatelimitHeader: "true",
+					header: map[string][]string{
+						codersdk.BypassRatelimitHeader: {"true"},
 					},
 				},
 			}
@@ -515,8 +515,8 @@ It is recommended that all rate limits are disabled on the server before running
 			client.HTTPClient = &http.Client{
 				Transport: &headerTransport{
 					transport: http.DefaultTransport,
-					headers: map[string]string{
-						codersdk.BypassRatelimitHeader: "true",
+					header: map[string][]string{
+						codersdk.BypassRatelimitHeader: {"true"},
 					},
 				},
 			}