Secrets encryption at rest in Kubernetes - Commands & Configuration

Introduction

When you store sensitive information like passwords or keys in Kubernetes, you want to keep them safe even if someone accesses the storage directly. Secrets encryption at rest means the data is stored encrypted on disk, so it stays protected.

When you want to protect sensitive data like API keys or passwords stored in Kubernetes Secrets from being read directly from disk.

When your Kubernetes cluster is running in a shared environment and you want to add an extra layer of security for stored secrets.

When compliance rules require encryption of sensitive data stored on persistent storage.

When you want to prevent attackers who gain access to etcd storage from reading secrets in plain text.

When you want to secure secrets without changing how your applications access them.

Config File - encryption-config.yaml

encryption-config.yaml

apiVersion: apiserver.config.k8s.io/v1
kind: EncryptionConfiguration
resources:
  - resources:
      - secrets
    providers:
      - aescbc:
          keys:
            - name: key1
              secret: c2VjcmV0a2V5MTIzNDU2Nzg5MDEyMzQ1Njc4OTA=
      - identity: {}

This file tells Kubernetes to encrypt Secrets using AES-CBC with the provided key named key1. The secret is a base64-encoded 32-byte key. The identity provider means if encryption fails, data is stored as plain text (fallback).

The resources section specifies that only Secrets are encrypted.

Commands

Check existing secrets in the default namespace before enabling encryption to see current data.

Terminal

kubectl get secrets -n default

Expected Output

NAME                  TYPE                                  DATA   AGE

my-secret             Opaque                                1      10m

Place the encryption configuration file on the Kubernetes master node in the correct directory for the API server to use.

Terminal

sudo mv /path/to/encryption-config.yaml /etc/kubernetes/encryption-config.yaml

Expected Output

No output (command runs silently)

Add the environment variable to the kube-apiserver service to tell it where to find the encryption config file.

Terminal

sudo sed -i '/kube-apiserver.service/a Environment="KUBE_ENCRYPTION_PROVIDER_CONFIG=/etc/kubernetes/encryption-config.yaml"' /etc/systemd/system/kube-apiserver.service

Expected Output

No output (command runs silently)

Reload systemd to apply changes and restart the API server so it uses the new encryption settings.

Terminal

sudo systemctl daemon-reload && sudo systemctl restart kube-apiserver

Expected Output

No output (command runs silently)

Verify secrets are still accessible after enabling encryption at rest.

Terminal

kubectl get secrets -n default

Expected Output

NAME                  TYPE                                  DATA   AGE

my-secret             Opaque                                1      12m

Check the raw secret data stored in etcd to confirm it is encrypted (will show unreadable data).

Terminal

ETCDCTL_API=3 etcdctl get /registry/secrets/default/my-secret --endpoints=https://127.0.0.1:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt --cert=/etc/kubernetes/pki/etcd/server.crt --key=/etc/kubernetes/pki/etcd/server.key

Expected Output

k8s:enc:aescbc:v1:key1

x12x34x56x78x90xabxcdxef...

→

--endpoints - Specify etcd server address

→

--cacert - CA certificate for etcd TLS

→

--cert - Client certificate for etcd TLS

→

--key - Client key for etcd TLS

Key Concept

If you remember nothing else from this pattern, remember: enabling encryption at rest protects Kubernetes Secrets stored in etcd from being read in plain text.

Common Mistakes

Not restarting the kube-apiserver after adding the encryption config.

The API server won't use the new encryption settings until it restarts, so secrets remain unencrypted.

Always reload systemd and restart kube-apiserver after changing encryption configuration.

Using a base64 key that is not 32 bytes long for AES-CBC encryption.

The encryption key must be exactly 32 bytes (256 bits) base64-encoded, or encryption will fail.

Generate a proper 32-byte base64 key using a secure method like openssl.

Not backing up existing secrets before enabling encryption.

If something goes wrong, you could lose access to secrets or corrupt data.

Always backup etcd data and secrets before enabling encryption at rest.

Summary

Create an encryption configuration file specifying AES-CBC encryption for Kubernetes Secrets.

Configure the kube-apiserver to use this encryption config and restart it to apply changes.

Verify secrets remain accessible and confirm data is encrypted in etcd storage.

Practice

1. What is the main purpose of enabling Secrets encryption at rest in Kubernetes?

easy

A. To protect sensitive data stored in etcd from unauthorized access

B. To speed up the retrieval of Secrets from the API server

C. To allow Secrets to be shared publicly across namespaces

D. To automatically rotate Secrets without manual intervention

Solution

1. Step 1: Understand what Secrets encryption at rest means

   It means encrypting sensitive data stored on disk, specifically in etcd, to prevent unauthorized access if someone gains access to the storage.

2. Step 2: Identify the main goal of this encryption

   The goal is to protect sensitive data like passwords or tokens stored in etcd, not to speed up access or share Secrets publicly.

3. Final Answer:

   To protect sensitive data stored in etcd from unauthorized access -> Option A

4. Quick Check:

   Secrets encryption = protect data at rest [OK]

Hint: Encryption at rest means protecting stored data, not speeding access [OK]

Common Mistakes:

• Confusing encryption at rest with encryption in transit
• Thinking encryption shares Secrets publicly
• Assuming encryption automatically rotates Secrets

2. Which of the following is the correct way to enable Secrets encryption at rest in Kubernetes EncryptionConfiguration file?

easy

A. apiVersion: apiserver.config.k8s.io/v1
kind: EncryptionConfiguration
resources:
- resources:
- secrets
providers:
- aescbc:
keys:
- name: key1
secret:
- identity: {}

B. apiVersion: v1
kind: Secret
metadata:
name: encryption-config
stringData:
key:

C. apiVersion: apiserver.config.k8s.io/v1
kind: EncryptionConfiguration
resources:
- secrets
providers:
- identity: {}
- aescbc:
keys:
- name: key1
secret:

D. apiVersion: apiserver.config.k8s.io/v1
kind: EncryptionConfig
resources:
- secrets
- aescbc:
keys:
- name: key1
secret:

Solution

1. Step 1: Review the correct structure of EncryptionConfiguration

   The file must have apiVersion, kind, and a resources list with nested resources and providers. The providers list includes encryption methods like aescbc and identity.

2. Step 2: Compare options for correct YAML syntax and structure

   apiVersion: apiserver.config.k8s.io/v1 kind: EncryptionConfiguration resources: - secrets providers: - identity: {} - aescbc: keys: - name: key1 secret: correctly nests resources and providers, uses aescbc with keys, and includes identity as fallback. apiVersion: apiserver.config.k8s.io/v1 kind: EncryptionConfiguration resources: - resources: - secrets providers: - aescbc: keys: - name: key1 secret: - identity: {} incorrectly nests 'resources' under 'resources'. Others have syntax errors or wrong kind names.

3. Final Answer:

   apiVersion: apiserver.config.k8s.io/v1 kind: EncryptionConfiguration resources: - secrets providers: - identity: {} - aescbc: keys: - name: key1 secret: -> Option C

4. Quick Check:

   Correct YAML structure = apiVersion: apiserver.config.k8s.io/v1 kind: EncryptionConfiguration resources: - secrets providers: - identity: {} - aescbc: keys: - name: key1 secret: [OK]

Hint: Look for 'resources' as a list of resource names and 'providers' as a list of encryption methods [OK]

Common Mistakes:

• Using wrong kind name like EncryptionConfig instead of EncryptionConfiguration
• Incorrect YAML indentation or missing nested keys
• Placing keys outside the providers list
• Nesting 'resources' under 'resources' incorrectly

3. Given this snippet from a Kubernetes API server log after enabling Secrets encryption at rest:

"Encryption provider aescbc is enabled for resource secrets"
"Using key named key1 for encryption"
"Secrets stored in etcd are now encrypted"

What is the expected effect when retrieving a Secret via kubectl get secret?

medium

A. The Secret data is shown as base64-encoded encrypted strings

B. The Secret data is automatically decrypted and shown in base64-encoded plain text

C. The Secret cannot be retrieved until manual decryption is done

D. The Secret is deleted from etcd after retrieval

Solution

1. Step 1: Understand encryption at rest vs API response

   Encryption at rest means data is encrypted in storage (etcd), but the API server decrypts it before sending to clients.

2. Step 2: Determine what kubectl get secret shows

   kubectl shows the decrypted Secret data in base64-encoded form, which is normal for Secrets, not encrypted ciphertext.

3. Final Answer:

   The Secret data is automatically decrypted and shown in base64-encoded plain text -> Option B

4. Quick Check:

   Encryption at rest decrypts before API response [OK]

Hint: Encryption at rest is transparent to kubectl output [OK]

Common Mistakes:

• Thinking Secrets remain encrypted when retrieved
• Confusing base64 encoding with encryption
• Assuming manual decryption is needed

4. You configured Secrets encryption at rest but notice that Secrets are still stored unencrypted in etcd. What is the most likely cause?

medium

A. The Secrets were created before enabling encryption and never updated

B. The encryption key is too short and rejected silently

C. The etcd cluster does not support encryption

D. The API server was not restarted after applying the encryption config

Solution

1. Step 1: Recall how encryption config is applied

   The API server must be restarted to load the new encryption configuration and apply encryption to new Secrets.

2. Step 2: Identify why Secrets remain unencrypted

   If the API server is not restarted, it continues to store Secrets unencrypted despite config changes.

3. Final Answer:

   The API server was not restarted after applying the encryption config -> Option D

4. Quick Check:

   Restart API server to apply encryption config [OK]

Hint: Always restart API server after changing encryption config [OK]

Common Mistakes:

• Assuming existing Secrets auto-encrypt without update
• Believing etcd cannot support encryption
• Ignoring the need to restart API server

5. You want to rotate the encryption key used for Secrets encryption at rest without downtime. Which approach correctly achieves this?

hard

A. Add the new key as the first provider in the encryption config, keep the old key second, then restart the API server

B. Replace the old key with the new key in the config and restart the API server immediately

C. Delete all Secrets, update the key, then recreate Secrets encrypted with the new key

D. Update the key in etcd directly without changing the API server config

Solution

1. Step 1: Understand key rotation in encryption config

   To rotate keys safely, add the new key first so new Secrets encrypt with it, and keep the old key to decrypt existing Secrets.

2. Step 2: Apply config and restart API server

   Restarting the API server loads the new config. Existing Secrets remain decryptable with the old key, allowing smooth rotation.

3. Final Answer:

   Add the new key as the first provider in the encryption config, keep the old key second, then restart the API server -> Option A

4. Quick Check:

   New key first, old key second, restart API server [OK]

Hint: New key first, old key second in config for smooth rotation [OK]

Common Mistakes:

• Replacing old key immediately causing decryption failures
• Deleting Secrets instead of rotating keys
• Modifying etcd data directly risking corruption