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don't use a custom dialer for the kubelet

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Don't use a custom dialer for the kubelet if is not rotating
certificates, so we can reuse TCP connections because we don't need
a customer dialer.

Kubelet needs to be able to recover from stale http connections.
HTTP2 has a mechanism to detect broken connections by sending periodical pings.
HTTP1 only can have one persistent connection, and it will close all Idle connections
once the Kubelet heartbet fails. However, since there are many edge cases that we can't
control, users can still opt-in to the previous behavior for closing the connections by
setting the environment variable DISABLE_HTTP2.
This commit is contained in:
Antonio Ojea 2021-09-21 23:38:47 +02:00
parent b9d865a818
commit 15ea255457
1 changed files with 18 additions and 3 deletions
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21
cmd/kubelet/app/server.go
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@ -44,6 +44,7 @@ import (
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/runtime" "k8s.io/apimachinery/pkg/runtime"
"k8s.io/apimachinery/pkg/types" "k8s.io/apimachinery/pkg/types"
utilnet "k8s.io/apimachinery/pkg/util/net"
utilruntime "k8s.io/apimachinery/pkg/util/runtime" utilruntime "k8s.io/apimachinery/pkg/util/runtime"
"k8s.io/apimachinery/pkg/util/sets" "k8s.io/apimachinery/pkg/util/sets"
"k8s.io/apimachinery/pkg/util/wait" "k8s.io/apimachinery/pkg/util/wait"
@ -933,9 +934,23 @@ func buildKubeletClientConfig(ctx context.Context, s *options.KubeletServer, nod
} }
kubeClientConfigOverrides(s, clientConfig) kubeClientConfigOverrides(s, clientConfig)
closeAllConns, err := updateDialer(clientConfig) // Kubelet needs to be able to recover from stale http connections.
if err != nil { // HTTP2 has a mechanism to detect broken connections by sending periodical pings.
return nil, nil, err // HTTP1 only can have one persistent connection, and it will close all Idle connections
// once the Kubelet heartbeat fails. However, since there are many edge cases that we can't
// control, users can still opt-in to the previous behavior for closing the connections by
// setting the environment variable DISABLE_HTTP2.
var closeAllConns func()
if s := os.Getenv("DISABLE_HTTP2"); len(s) > 0 {
klog.InfoS("HTTP2 has been explicitly disabled, updating Kubelet client Dialer to forcefully close active connections on heartbeat failures")
closeAllConns, err = updateDialer(clientConfig)
if err != nil {
return nil, nil, err
}
} else {
closeAllConns = func() {
utilnet.CloseIdleConnectionsFor(clientConfig.Transport)
}
} }
return clientConfig, closeAllConns, nil return clientConfig, closeAllConns, nil
} }