From 0b6225bcc3cc9b6635cd3b0fcff9fdbd3dbf9964 Mon Sep 17 00:00:00 2001
From: Anis Elleuch <vadmeste@users.noreply.github.com>
Date: Mon, 6 Dec 2021 18:44:48 +0100
Subject: [PATCH] Better error msg when version mismatch of internode API
 (#13845)

Sometimes, we see an error message like "Server expects 'storage' API
version 'v41', instead found 'v41'" shows a more generic error message
with the path of the REST call.
---
 cmd/handler-utils.go | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/cmd/handler-utils.go b/cmd/handler-utils.go
index ceb8208ea..3f0958cb3 100644
--- a/cmd/handler-utils.go
+++ b/cmd/handler-utils.go
@@ -429,6 +429,18 @@ func extractAPIVersion(r *http.Request) string {
 	return "unknown"
 }
 
+func generateUnexpectedRPCMsg(rpcPath, subsystem string, expectedVersion, gotVersion string) string {
+	var reason string
+	switch {
+	case expectedVersion != gotVersion:
+		reason = fmt.Sprintf("Server expects '%s' API version '%s', instead found '%s'", subsystem, expectedVersion, gotVersion)
+	default:
+		reason = fmt.Sprintf("Unexpected RPC call at this path '%s'", rpcPath)
+	}
+
+	return fmt.Sprintf("%s - *rolling upgrade is not allowed* - please make sure all servers are running the same MinIO version (%s)", reason, ReleaseTag)
+}
+
 func methodNotAllowedHandler(api string) func(w http.ResponseWriter, r *http.Request) {
 	return func(w http.ResponseWriter, r *http.Request) {
 		if r.Method == http.MethodOptions {
@@ -437,21 +449,21 @@ func methodNotAllowedHandler(api string) func(w http.ResponseWriter, r *http.Req
 		version := extractAPIVersion(r)
 		switch {
 		case strings.HasPrefix(r.URL.Path, peerRESTPrefix):
-			desc := fmt.Sprintf("Server expects 'peer' API version '%s', instead found '%s' - *rolling upgrade is not allowed* - please make sure all servers are running the same MinIO version (%s)", peerRESTVersion, version, ReleaseTag)
+			desc := generateUnexpectedRPCMsg(r.URL.Path, "peer", peerRESTVersion, version)
 			writeErrorResponseString(r.Context(), w, APIError{
 				Code:           "XMinioPeerVersionMismatch",
 				Description:    desc,
 				HTTPStatusCode: http.StatusUpgradeRequired,
 			}, r.URL)
 		case strings.HasPrefix(r.URL.Path, storageRESTPrefix):
-			desc := fmt.Sprintf("Server expects 'storage' API version '%s', instead found '%s' - *rolling upgrade is not allowed* - please make sure all servers are running the same MinIO version (%s)", storageRESTVersion, version, ReleaseTag)
+			desc := generateUnexpectedRPCMsg(r.URL.Path, "storage", storageRESTVersion, version)
 			writeErrorResponseString(r.Context(), w, APIError{
 				Code:           "XMinioStorageVersionMismatch",
 				Description:    desc,
 				HTTPStatusCode: http.StatusUpgradeRequired,
 			}, r.URL)
 		case strings.HasPrefix(r.URL.Path, lockRESTPrefix):
-			desc := fmt.Sprintf("Server expects 'lock' API version '%s', instead found '%s' - *rolling upgrade is not allowed* - please make sure all servers are running the same MinIO version (%s)", lockRESTVersion, version, ReleaseTag)
+			desc := generateUnexpectedRPCMsg(r.URL.Path, "lock", lockRESTVersion, version)
 			writeErrorResponseString(r.Context(), w, APIError{
 				Code:           "XMinioLockVersionMismatch",
 				Description:    desc,