Sign CSRs for kubelet-serving with the server CA

Problem: Only the client CA is passed to the kube-controller-manager and therefore CSRs with the signer name "kubernetes.io/kubelet-serving" are signed with the client CA. Serving certificates must be signed with the server CA otherwise e.g. "kubectl logs" fails with the error message "x509: certificate signed by unknown authority". Solution: Instead of providing only one CA via the kube-controller-manager parameter "--cluster-signing-cert-file", the corresponding CA for every signer is set with the parameters "--cluster-signing-kube-apiserver-client-cert-file", "--cluster-signing-kubelet-client-cert-file", "--cluster-signing-kubelet-serving-cert-file", and "--cluster-signing-legacy-unknown-cert-file". Signed-off-by: Siegfried Weber <mail@siegfriedweber.net> (cherry picked from commit e77fd182)

Sign CSRs for kubelet-serving with the server CA
2b2f3182 · Siegfried Weber · Brad Davidson · f8311d6f · 2b2f3182
Commit 2b2f3182 authored May 01, 2021 by Siegfried Weber Committed by Brad Davidson Jul 08, 2021
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server.go pkg/daemons/control/server.go +8 -2

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--- a/pkg/daemons/control/server.go
+++ b/pkg/daemons/control/server.go
@@ -103,8 +103,14 @@ func controllerManager(cfg *config.Control, runtime *config.ControlRuntime) erro
 		"bind-address":                     localhostIP.String(),
 		"secure-port":                      "0",
 		"use-service-account-credentials":  "true",
-		"cluster-signing-cert-file":        runtime.ClientCA,
-		"cluster-signing-key-file":         runtime.ClientCAKey,
+		"cluster-signing-kube-apiserver-client-cert-file": runtime.ClientCA,
+		"cluster-signing-kube-apiserver-client-key-file":  runtime.ClientCAKey,
+		"cluster-signing-kubelet-client-cert-file":        runtime.ClientCA,
+		"cluster-signing-kubelet-client-key-file":         runtime.ClientCAKey,
+		"cluster-signing-kubelet-serving-cert-file":       runtime.ServerCA,
+		"cluster-signing-kubelet-serving-key-file":        runtime.ServerCAKey,
+		"cluster-signing-legacy-unknown-cert-file":        runtime.ClientCA,
+		"cluster-signing-legacy-unknown-key-file":         runtime.ClientCAKey,
 	}
 	if cfg.NoLeaderElect {
 		argsMap["leader-elect"] = "false"