k3s secrets-encrypt

K3s supports enabling secrets encryption at rest. For more information, see Secrets Encryption.

Secrets Encryption Tool

Version Gate

Available as of v1.21.8+k3s1

K3s contains a CLI tool secrets-encrypt, which enables automatic control over the following:

• Disabling/Enabling secrets encryption
• Adding new encryption keys
• Rotating and deleting encryption keys
• Reencrypting secrets

caution

Failure to follow proper procedure for rotating encryption keys can leave your cluster permanently corrupted. Proceed with caution.

Encryption Key Rotation

• Single-Server
• High-Availability

To rotate secrets encryption keys on a single-server cluster:

• Start the K3s server with the flag --secrets-encryption

note

Starting K3s without encryption and enabling it at a later time is currently not supported.

1. Prepare

   k3s secrets-encrypt prepare

2. Kill and restart the K3s server with same arguments. If running K3s as a service:

   # If using systemd
   systemctl restart k3s
   # If using openrc
   rc-service k3s restart

3. Rotate

   k3s secrets-encrypt rotate

4. Kill and restart the K3s server with same arguments

5. Reencrypt

   info

   K3s will reencrypt ~5 secrets per second.
   Clusters with large # of secrets can take several minutes to reencrypt.

   k3s secrets-encrypt reencrypt

The steps are the same for both embedded DB and external DB clusters.

To rotate secrets encryption keys on HA setups:

Notes

• Starting K3s without encryption and enabling it at a later time is currently not supported.
• While not required, it is recommended that you pick one server node from which to run the secrets-encrypt commands.

1. Start up all three K3s servers with the --secrets-encryption flag. For brevity, the servers will be referred to as S1, S2, S3.

2. Prepare on S1

   k3s secrets-encrypt prepare

3. Kill and restart S1 with same arguments. If running K3s as a service:

   # If using systemd
   systemctl restart k3s
   # If using openrc
   rc-service k3s restart

4. Once S1 is up, kill and restart the S2 and S3

5. Rotate on S1

   k3s secrets-encrypt rotate

6. Kill and restart S1 with same arguments

7. Once S1 is up, kill and restart the S2 and S3

8. Reencrypt on S1

   info

   K3s will reencrypt ~5 secrets per second.
   Clusters with large # of secrets can take several minutes to reencrypt.

   k3s secrets-encrypt reencrypt

9. Kill and restart S1 with same arguments

10. Once S1 is up, kill and restart the S2 and S3

Secrets Encryption Disable/Enable

• Single-Server
• High-Availability

After launching a server with --secrets-encryption flag, secrets encryption can be disabled.

To disable secrets encryption on a single-node cluster:

1. Disable

   k3s secrets-encrypt disable

2. Kill and restart the K3s server with same arguments. If running K3s as a service:

   # If using systemd
   systemctl restart k3s
   # If using openrc
   rc-service k3s restart

3. Reencrypt with flags

   k3s secrets-encrypt reencrypt --force --skip

To re-enable secrets encryption on a single node cluster:

1. Enable

   k3s secrets-encrypt enable

2. Kill and restart the K3s server with same arguments

3. Reencrypt with flags

   k3s secrets-encrypt reencrypt --force --skip

After launching a HA cluster with --secrets-encryption flags, secrets encryption can be disabled.

note

While not required, it is recommended that you pick one server node from which to run the secrets-encrypt commands.

For brevity, the three servers used in this guide will be referred to as S1, S2, S3.

To disable secrets encryption on a HA cluster:

1. Disable on S1

   k3s secrets-encrypt disable

2. Kill and restart S1 with same arguments. If running K3s as a service:

   # If using systemd
   systemctl restart k3s
   # If using openrc
   rc-service k3s restart

3. Once S1 is up, kill and restart the S2 and S3

4. Reencrypt with flags on S1

   k3s secrets-encrypt reencrypt --force --skip

To re-enable secrets encryption on a HA cluster:

1. Enable on S1

   k3s secrets-encrypt enable

2. Kill and restart S1 with same arguments

3. Once S1 is up, kill and restart the S2 and S3

4. Reencrypt with flags on S1

   k3s secrets-encrypt reencrypt --force --skip

Secrets Encryption Status

The secrets-encrypt tool includes a status command that displays information about the current status of secrets encryption on the node.

An example of the command on a single-server node:

$ k3s secrets-encrypt status
Encryption Status: Enabled
Current Rotation Stage: start
Server Encryption Hashes: All hashes match
Active  Key Type  Name
------  --------  ----
 *      AES-CBC   aescbckey

Another example on HA cluster, after rotating the keys, but before restarting the servers:

$ k3s secrets-encrypt status
Encryption Status: Enabled
Current Rotation Stage: rotate
Server Encryption Hashes: hash does not match between node-1 and node-2
Active  Key Type  Name
------  --------  ----
 *      AES-CBC   aescbckey-2021-12-10T22:54:38Z
        AES-CBC   aescbckey

Details on each section are as follows:

• Encryption Status: Displayed whether secrets encryption is disabled or enabled on the node
• Current Rotation Stage: Indicates the current rotation stage on the node.
  Stages are: start, prepare, rotate, reencrypt_request, reencrypt_active, reencrypt_finished
• Server Encryption Hashes: Useful for HA clusters, this indicates whether all servers are on the same stage with their local files. This can be used to identify whether a restart of servers is required before proceeding to the next stage. In the HA example above, node-1 and node-2 have different hashes, indicating that they currently do not have the same encryption configuration. Restarting the servers will sync up their configuration.
• Key Table: Summarizes information about the secrets encryption keys found on the node.
  • Active: The “*“ indicates which, if any, of the keys are currently used for secrets encryption. An active key is used by Kubernetes to encrypt any new secrets.
  • Key Type: All keys using this tool are AES-CBC type. See more info here.
  • Name: Name of the encryption key.