Add ns query parameter when using a mirror endpoint

This is required by some registries that are capable of serving multiple upstreams

Signed-off-by: Brad Davidson <[email protected]>

pkg/registries/endpoint.go

@@ -13,6 +13,11 @@ import (
 var _ authn.Keychain = &endpoint{}
 var _ http.RoundTripper = &endpoint{}
 
+const (
+	defaultRegistry     = "docker.io"
+	defaultRegistryHost = "index.docker.io"
+)
+
 type endpoint struct {
 	auth     authn.Authenticator
 	keychain authn.Keychain
@@ -69,7 +74,12 @@ func (e endpoint) RoundTrip(req *http.Request) (*http.Response, error) {
 			}
 		}
 
-		// override request host and scheme
+		// override request host and scheme; set ns from original host
+		if req.Host == defaultRegistryHost {
+			req.URL.Query().Set("ns", defaultRegistry)
+		} else {
+			req.URL.Query().Set("ns", req.Host)
+		}
 		req.Host = endpointURL.Host
 		req.URL.Host = endpointURL.Host
 		req.URL.Scheme = endpointURL.Scheme