From b5378b3a5dd435e5c364ac0cfa717112ad686bd0 Mon Sep 17 00:00:00 2001
From: Cenk Alti <cenkalti@gmail.com>
Date: Mon, 10 Oct 2022 21:55:18 -0400
Subject: [PATCH] retry http request on temporary errors

Signed-off-by: Cenk Alti <cenkalti@gmail.com>
---
 pkg/cli/environment.go  |  4 +++
 pkg/cli/roundtripper.go | 77 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 81 insertions(+)
 create mode 100644 pkg/cli/roundtripper.go

diff --git a/pkg/cli/environment.go b/pkg/cli/environment.go
index ac3093629..ef04ed6bd 100644
--- a/pkg/cli/environment.go
+++ b/pkg/cli/environment.go
@@ -24,6 +24,7 @@ package cli
 
 import (
 	"fmt"
+	"net/http"
 	"os"
 	"strconv"
 	"strings"
@@ -116,6 +117,9 @@ func New() *EnvSettings {
 		ImpersonateGroup: &env.KubeAsGroups,
 		WrapConfigFn: func(config *rest.Config) *rest.Config {
 			config.Burst = env.BurstLimit
+			config.Wrap(func(rt http.RoundTripper) http.RoundTripper {
+				return &retryingRoundTripper{wrapped: rt}
+			})
 			return config
 		},
 	}
diff --git a/pkg/cli/roundtripper.go b/pkg/cli/roundtripper.go
new file mode 100644
index 000000000..ab90ed2e1
--- /dev/null
+++ b/pkg/cli/roundtripper.go
@@ -0,0 +1,77 @@
+/*
+Copyright The Helm Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cli
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+)
+
+type retryingRoundTripper struct {
+	wrapped http.RoundTripper
+}
+
+func (rt *retryingRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	return rt.roundTrip(req, 1, nil)
+}
+
+func (rt *retryingRoundTripper) roundTrip(req *http.Request, retry int, prevResp *http.Response) (*http.Response, error) {
+	if retry < 0 {
+		return prevResp, nil
+	}
+	resp, rtErr := rt.wrapped.RoundTrip(req)
+	if rtErr != nil {
+		return resp, rtErr
+	}
+	if resp.Header.Get("content-type") != "application/json" {
+		return resp, rtErr
+	}
+	b, err := io.ReadAll(resp.Body)
+	resp.Body.Close()
+	if err != nil {
+		return resp, rtErr
+	}
+
+	var ke kubernetesError
+	r := bytes.NewReader(b)
+	err = json.NewDecoder(r).Decode(&ke)
+	r.Seek(0, io.SeekStart)
+	resp.Body = io.NopCloser(r)
+	if err != nil {
+		return resp, rtErr
+	}
+	if ke.Code < 500 {
+		return resp, rtErr
+	}
+	// Matches messages like "etcdserver: leader changed"
+	if strings.HasSuffix(ke.Message, "etcdserver: leader changed") {
+		return rt.roundTrip(req, retry-1, resp)
+	}
+	// Matches messages like "rpc error: code = Unknown desc = raft proposal dropped"
+	if strings.HasSuffix(ke.Message, "raft proposal dropped") {
+		return rt.roundTrip(req, retry-1, resp)
+	}
+	return resp, rtErr
+}
+
+type kubernetesError struct {
+	Message string `json:"message"`
+	Code    int    `json:"code"`
+}