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Google Distributed Cloud use certificates and private keys to authenticate
communication between Kubernetes system components in an admin cluster. When you
create an admin cluster, new certificate authority (CA) certificates are created,
and these root certificates are used to issue additional leaf certificates for
Kubernetes system components.
There are three CA certificates used by the Kubernetes system in an admin
cluster:
The etcd CA certificate secures communication from the Kubernetes API server
to the etcd replicas and also communication between etcd replicas. This
certificate is self-signed.
The cluster CA certificate secures communication between the Kubernetes API
server and all internal Kubernetes API clients, for example, the kubelet, the
controller manager, and the scheduler. This certificate is self-signed.
The front-proxy CA certificate secures communication with
aggregated APIs.
This certificate is self-signed.
You can use gkectl to trigger a certificate rotation. During a rotation,
gkectl replaces the core system CA certificates for the
admin cluster with newly generated certificates. Then it distributes the new
CA certificates, leaf certificates, and private keys to admin cluster system
components. The rotation happens incrementally, so that system components can
continue to communicate during the rotation. Note, however, that workloads and
nodes are restarted during the rotation.
Without rotation, CA certificates and control-plane certificates will expire
five years from the date the cluster was created. The control plane certificates
are automatically rotated during a cluster upgrade, but the CAs are
not automatically rotated. This means a CA rotation must be performed at least
once every five years, in addition to regular version upgrades.
Limitations
Note the following limitation with advanced clusters:
Version 1.32 and higher: CA rotation is supported on advanced clusters but
there are some minor differences noted where applicable in this document.
CA certificate rotation limited to the etcd, cluster, and front-proxy
certificates mentioned previously.
CA certificate rotation is limited to certificates issued automatically by
Google Distributed Cloud. It does not update certificates issued manually by an
administrator, even if those certificates are signed by the system CAs.
CA certificate rotation restarts the Kubernetes API server, other
control-plane processes, and each node in the admin cluster multiple times.
Each stage of a rotation progresses similarly to a cluster upgrade. While the
admin cluster and the user clusters managed by the admin cluster do remain
operational during a certificate rotation, you should expect that workloads
in the admin cluster will be restarted and rescheduled. You should also expect
brief periods of downtime for the admin cluster control plane and user cluster
control plane.
You must update the admin cluster kubeconfig file in the middle of a
certificate rotation and again after the rotation completes. This is because
the old cluster certificate is revoked, and the credentials in the kubeconfig
file will no longer work.
Once initiated, a CA certificate rotation cannot be rolled back.
A CA certificate rotation might take considerable time to complete, depending
on the size of the cluster.
The certificate rotation process can be resumed by re-running the same
command if it is interrupted. However, you must ensure that there is only one
rotation command running at a time.
Start the rotation
To start the certificate rotation, run the following command:
ADMIN_CLUSTER_CONFIG: the path of the admin cluster configuration
file
ADMIN_CLUSTER_KUBECONFIG: the path of the admin cluster kubeconfig
file
The behavior of the command differs depending on whether advanced cluster
is enabled:
Not enabled
The gkectl update credentials certificate-authorities rotate command starts
and performs the first half of the rotation. The command then pauses to let
you run the next command to update the kubeconfig file.
Update the kubeconfig file
When the gkectl update credentials certificate-authorities rotate command
pauses, update the kubeconfig file for the admin cluster. This places a new
client certificate and a new CA certificate in the kubeconfig file. The old
client certificate is removed from the kubeconfig file, and the old CA
certificate remains in the kubeconfig file.
Run the following command to perform the second half of the procedure. The
command doesn't proceed until gkectl verifies that the updated kubeconfig
file is in the current directory.
If advanced cluster is enabled, the gkectl update credentials
certificate-authorities rotate command is synchronous. The command outputs
status messages to the admin workstation as the CA rotation progresses.
After the CA is rotated successfully, the command exits and a new kubeconfig
file is automatically generated. The kubeconfig file that you specified in the
command is replaced with a new one. The command output is similar to the
following:
Beginning CA rotation with generated CA
...
Successfully rotated CA for admin cluster. The kubeconfig file
"/home/ubuntu/kubeconfig" has been updated.
Done rotating certificate-authorities
Distribute the new kubeconfig file
Distribute the new admin cluster kubeconfig file to all cluster users.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-25 UTC."],[],[],null,["# Rotating admin cluster CA certificates\n\nGoogle Distributed Cloud use certificates and private keys to authenticate\ncommunication between Kubernetes system components in an admin cluster. When you\ncreate an admin cluster, new certificate authority (CA) certificates are created,\nand these root certificates are used to issue additional leaf certificates for\nKubernetes system components.\n\nThis guide applies only to rotation of admin cluster CA certificates. For\nuser clusters, see\n[Rotating user cluster CA certificates](/kubernetes-engine/distributed-cloud/vmware/docs/how-to/ca-rotation).\n\nThere are three CA certificates used by the Kubernetes system in an admin\ncluster:\n\n- The etcd CA certificate secures communication from the Kubernetes API server\n to the etcd replicas and also communication between etcd replicas. This\n certificate is self-signed.\n\n- The cluster CA certificate secures communication between the Kubernetes API\n server and all internal Kubernetes API clients, for example, the kubelet, the\n controller manager, and the scheduler. This certificate is self-signed.\n\n- The front-proxy CA certificate secures communication with\n [aggregated APIs](https://kubernetes.io/docs/concepts/extend-kubernetes/api-extension/apiserver-aggregation/).\n This certificate is self-signed.\n\nYou can use `gkectl` to trigger a certificate rotation. During a rotation,\n`gkectl` replaces the core system CA certificates for the\nadmin cluster with newly generated certificates. Then it distributes the new\nCA certificates, leaf certificates, and private keys to admin cluster system\ncomponents. The rotation happens incrementally, so that system components can\ncontinue to communicate during the rotation. Note, however, that workloads and\nnodes are restarted during the rotation.\n\nWithout rotation, CA certificates and control-plane certificates will expire\nfive years from the date the cluster was created. The control plane certificates\nare automatically rotated during a cluster upgrade, but the CAs are\nnot automatically rotated. This means a CA rotation must be performed at least\nonce every five years, in addition to regular version upgrades.\n| **Warning:** A CA certificate rotation revokes the old CA certificates at the end of the operation. This invalidates kubeconfig files that were based on an old certificate. Consequently, the credentials in the kubeconfig file stop working after a CA certificate rotation. This guide includes instructions on how to update your kubeconfig file. The same issue applies to authentication configuration files.\n\nLimitations\n-----------\n\n- Note the following limitation with advanced clusters:\n\n - Version 1.31: CA rotation isn't supported on [advanced clusters](/kubernetes-engine/distributed-cloud/vmware/docs/how-to/admin-cluster-configuration-file-latest#enable-advanced-cluster-field).\n - Version 1.32 and higher: CA rotation is supported on advanced clusters but there are some minor differences noted where applicable in this document.\n- CA certificate rotation limited to the etcd, cluster, and front-proxy\n certificates mentioned previously.\n\n- CA certificate rotation is limited to certificates issued automatically by\n Google Distributed Cloud. It does not update certificates issued manually by an\n administrator, even if those certificates are signed by the system CAs.\n\n- CA certificate rotation restarts the Kubernetes API server, other\n control-plane processes, and each node in the admin cluster multiple times.\n Each stage of a rotation progresses similarly to a cluster upgrade. While the\n admin cluster and the user clusters managed by the admin cluster do remain\n operational during a certificate rotation, you should expect that workloads\n in the admin cluster will be restarted and rescheduled. You should also expect\n brief periods of downtime for the admin cluster control plane and user cluster\n control plane.\n\n- You must update the admin cluster kubeconfig file in the middle of a\n certificate rotation and again after the rotation completes. This is because\n the old cluster certificate is revoked, and the credentials in the kubeconfig\n file will no longer work.\n\n- Once initiated, a CA certificate rotation cannot be rolled back.\n\n- A CA certificate rotation might take considerable time to complete, depending\n on the size of the cluster.\n\n- The certificate rotation process can be resumed by re-running the same\n command if it is interrupted. However, you must ensure that there is only one\n rotation command running at a time.\n\nStart the rotation\n------------------\n\nTo start the certificate rotation, run the following command:\n\n```\ngkectl update credentials certificate-authorities rotate \\\n --admin-cluster \\\n --config ADMIN_CLUSTER_CONFIG \\\n --kubeconfig ADMIN_CLUSTER_KUBECONFIG\n```\n\nReplace the following:\n\n- \u003cvar translate=\"no\"\u003eADMIN_CLUSTER_CONFIG\u003c/var\u003e: the path of the admin cluster configuration\n file\n\n- \u003cvar translate=\"no\"\u003eADMIN_CLUSTER_KUBECONFIG\u003c/var\u003e: the path of the admin cluster kubeconfig\n file\n\nThe behavior of the command differs depending on whether advanced cluster\nis enabled: \n\n### Not enabled\n\nThe `gkectl update credentials certificate-authorities rotate` command starts\nand performs the first half of the rotation. The command then pauses to let\nyou run the next command to update the kubeconfig file.\n\n### Update the kubeconfig file\n\nWhen the `gkectl update credentials certificate-authorities rotate` command\npauses, update the kubeconfig file for the admin cluster. This places a new\nclient certificate and a new CA certificate in the kubeconfig file. The old\nclient certificate is removed from the kubeconfig file, and the old CA\ncertificate remains in the kubeconfig file.\n\n```\ngkectl update credentials certificate-authorities update-kubeconfig \\\n --admin-cluster \\\n --config ADMIN_CLUSTER_CONFIG \\\n --kubeconfig ADMIN_CLUSTER_KUBECONFIG\n```\n\n### Continue the rotation\n\nRun the following command to perform the second half of the procedure. The\ncommand doesn't proceed until `gkectl` verifies that the updated kubeconfig\nfile is in the current directory.\n\n```\ngkectl update credentials certificate-authorities rotate \\\n --admin-cluster \\\n --complete \\\n --config ADMIN_CLUSTER_CONFIG \\\n --kubeconfig ADMIN_CLUSTER_KUBECONFIG\n```\n\nWhen the rotation is complete, it reports the current CA version.\n\n### Update the kubeconfig file again\n\nAfter the second half of the rotation completes, update the kubeconfig file\nagain. This removes the old CA certificate from the kubeconfig file.\n\n```\ngkectl update credentials certificate-authorities update-kubeconfig \\\n --admin-cluster \\\n --config ADMIN_CLUSTER_CONFIG \\\n --kubeconfig ADMIN_CLUSTER_KUBECONFIG\n```\n\n### Enabled\n\nIf advanced cluster is enabled, the `gkectl update credentials\ncertificate-authorities rotate` command is synchronous. The command outputs\nstatus messages to the admin workstation as the CA rotation progresses.\n\nAfter the CA is rotated successfully, the command exits and a new kubeconfig\nfile is automatically generated. The kubeconfig file that you specified in the\ncommand is replaced with a new one. The command output is similar to the\nfollowing:\n\n```\nBeginning CA rotation with generated CA\n...\nSuccessfully rotated CA for admin cluster. The kubeconfig file\n\"/home/ubuntu/kubeconfig\" has been updated.\nDone rotating certificate-authorities\n```\n\nDistribute the new kubeconfig file\n----------------------------------\n\nDistribute the new admin cluster kubeconfig file to all cluster users."]]
