<p>I am looking for private key being used to sign service account tokens in my cluster. Is there a way I can find path to this key or print it somehow?</p>

<p><a href="https://kubernetes.io/docs/reference/access-authn-authz/authentication/#service-account-tokens" rel="nofollow noreferrer">Documentation</a> says what flag is used to provide the key during startup but there is no info about current key in use.</p>

Prashant Singh Rathore
<p>You can check the path passed to <code>–service-account-private-key-file</code> parameter to the kube controller manager component. This is the key used by token controller to sign the service accounts.</p>

<pre><code>–service-account-private-key-file string
Filename containing a PEM-encoded private RSA or ECDSA key used to sign service account tokens.
</code></pre>

<p>In a cluster installed by kubeadm I could check the path by describing the pod <code>kube-controller-manager-kind-control-plane</code>(the pod name could be different in different cluster) in <code>kube-system</code> namespace</p>

<pre><code>kubectl describe pod kube-controller-manager-kind-control-plane -n kube-system
Name:                 kube-controller-manager-kind-control-plane
Namespace:            kube-system
Priority:             2000000000
Priority Class Name:  system-cluster-critical
Node:                 kind-control-plane/172.17.0.2
Start Time:           Tue, 14 Apr 2020 14:13:18 +0530
Labels:               component=kube-controller-manager
                      tier=control-plane
Annotations:          kubernetes.io/config.hash: 15e79e27a50d92dc481a5aaaad4399d8
                      kubernetes.io/config.mirror: 15e79e27a50d92dc481a5aaaad4399d8
                      kubernetes.io/config.seen: 2020-04-14T08:43:15.2951468Z
                      kubernetes.io/config.source: file
Status:               Running
IP:                   172.17.0.2
IPs:
  IP:           172.17.0.2
Controlled By:  Node/kind-control-plane
Containers:
  kube-controller-manager:
    Container ID:  containerd://6423f4d70cf0af2be708315b1aa5d4cb038d73b00b63f3d759db60e75f1ebf56
    Image:         k8s.gcr.io/kube-controller-manager:v1.17.0
    Image ID:      sha256:7818d75a7d002a3c1bb6e9d8fe4416e75ee7df87b57585ab4f8ef01ccba1ddaa
    Port:          &lt;none&gt;
    Host Port:     &lt;none&gt;
    Command:
      kube-controller-manager
      --allocate-node-cidrs=true
      --authentication-kubeconfig=/etc/kubernetes/controller-manager.conf
      --authorization-kubeconfig=/etc/kubernetes/controller-manager.conf
      --bind-address=127.0.0.1
      --client-ca-file=/etc/kubernetes/pki/ca.crt
      --cluster-cidr=10.244.0.0/16
      --cluster-signing-cert-file=/etc/kubernetes/pki/ca.crt
      --cluster-signing-key-file=/etc/kubernetes/pki/ca.key
      --controllers=*,bootstrapsigner,tokencleaner
      --enable-hostpath-provisioner=true
      --kubeconfig=/etc/kubernetes/controller-manager.conf
      --leader-elect=true
      --node-cidr-mask-size=24
      --requestheader-client-ca-file=/etc/kubernetes/pki/front-proxy-ca.crt
      --root-ca-file=/etc/kubernetes/pki/ca.crt
      --service-account-private-key-file=/etc/kubernetes/pki/sa.key
      --service-cluster-ip-range=10.96.0.0/12
      --use-service-account-credentials=true
</code></pre>

<p>As it can be seen above in a cluster installed by kubeadm the key file is located in master nodes at <code>/etc/kubernetes/pki/sa.key</code> location</p>

<p>Since you are on EKS managed cluster you will not have access to master nodes.</p>
