From 0d654d94e9e6509aec2548217b1795e8d8533de0 Mon Sep 17 00:00:00 2001
From: Hidde Beydals <hidde@hhh.computer>
Date: Tue, 14 Mar 2023 13:39:04 +0100
Subject: [PATCH] Use persistent `RESTClientGetter` in CLI

This changes the `RESTClientGetter` to one which caches the underlying
clients after first initialization.

This reduces memory usage for all commands, with observed reductions
from ~4MiB for `helm get all`, to ~10MiB for `helm install` (using
https://github.com/stefanprodan/podinfo).

For charts which make use of Custom Resource Definitions, this is
likely even higher as the client will not be initialized twice (one
time for the installation process of the CRDs, the second time for the
actual installation of the chart).

Follow up on #11886

Signed-off-by: Hidde Beydals <hidde@hhh.computer>
---
 pkg/cli/environment.go | 49 +++++++++++++++++++++++++-----------------
 1 file changed, 29 insertions(+), 20 deletions(-)

diff --git a/pkg/cli/environment.go b/pkg/cli/environment.go
index dac2a4bc1..81166c8af 100644
--- a/pkg/cli/environment.go
+++ b/pkg/cli/environment.go
@@ -106,29 +106,38 @@ func New() *EnvSettings {
 	env.Debug, _ = strconv.ParseBool(os.Getenv("HELM_DEBUG"))
 
 	// bind to kubernetes config flags
-	env.config = &genericclioptions.ConfigFlags{
-		Namespace:        &env.namespace,
-		Context:          &env.KubeContext,
-		BearerToken:      &env.KubeToken,
-		APIServer:        &env.KubeAPIServer,
-		CAFile:           &env.KubeCaFile,
-		KubeConfig:       &env.KubeConfig,
-		Impersonate:      &env.KubeAsUser,
-		Insecure:         &env.KubeInsecureSkipTLSVerify,
-		TLSServerName:    &env.KubeTLSServerName,
-		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}
-			})
-			config.UserAgent = version.GetUserAgent()
-			return config
-		},
-	}
+	env.config = buildConfigFlagsFromEnv(env)
 	return env
 }
 
+// buildConfigFlagsFromEnv builds a ConfigFlags object from the environment and
+// returns it. It uses a persistent config, meaning that underlying clients will
+// be cached and reused.
+func buildConfigFlagsFromEnv(env *EnvSettings) *genericclioptions.ConfigFlags {
+	flags := genericclioptions.NewConfigFlags(true)
+
+	flags.Namespace = &env.namespace
+	flags.Context = &env.KubeContext
+	flags.BearerToken = &env.KubeToken
+	flags.APIServer = &env.KubeAPIServer
+	flags.CAFile = &env.KubeCaFile
+	flags.KubeConfig = &env.KubeConfig
+	flags.Impersonate = &env.KubeAsUser
+	flags.Insecure = &env.KubeInsecureSkipTLSVerify
+	flags.TLSServerName = &env.KubeTLSServerName
+	flags.ImpersonateGroup = &env.KubeAsGroups
+	flags.WrapConfigFn = func(config *rest.Config) *rest.Config {
+		config.Burst = env.BurstLimit
+		config.Wrap(func(rt http.RoundTripper) http.RoundTripper {
+			return &retryingRoundTripper{wrapped: rt}
+		})
+		config.UserAgent = version.GetUserAgent()
+		return config
+	}
+
+	return flags
+}
+
 // AddFlags binds flags to the given flagset.
 func (s *EnvSettings) AddFlags(fs *pflag.FlagSet) {
 	fs.StringVarP(&s.namespace, "namespace", "n", s.namespace, "namespace scope for this request")