Kubernetes Secret Update from File: A Guide

• Introduction
• Step-by-Step Guide
• Code Example
• Additional Notes
• Summary
• Conclusion
• References

Kubernetes Secrets provide a secure way to manage sensitive information like passwords, API keys, and tokens, keeping them separate from your application code. This guide outlines how to create, view, update, delete, and use Secrets in your Kubernetes deployments.

Kubernetes Secrets store sensitive data like passwords and API keys. Here's how to manage them:

1. Create a Secret:

• From a file:

  kubectl create secret generic my-secret --from-file=my.key 

• Using literals:

  kubectl create secret generic my-secret --from-literal=username=admin --from-literal=password=secret

• With YAML:

  apiVersion: v1
  kind: Secret
  metadata:
    name: my-secret
  type: Opaque
  data:
    username: YWRtaW4=  # base64 encoded value of "admin"
    password: c2VjcmV0  # base64 encoded value of "secret"

  Apply with: kubectl apply -f secret.yaml

2. View a Secret:

kubectl get secret my-secret -o yaml

3. Update a Secret:

• Edit and apply YAML: Modify the secret.yaml file and re-apply with kubectl apply -f secret.yaml.
• Use kubectl patch:

  kubectl patch secret my-secret --patch '{"data":{"password":"bmV3cGFzc3dvcmQ="}}' 

  (Replace bmV3cGFzc3dvcmQ= with the base64 encoded new password)

4. Delete a Secret:

kubectl delete secret my-secret

5. Use a Secret in a Pod:

• Mount as volume:

  volumeMounts:
  - name: my-secret-volume
    mountPath: /etc/my-secret
  volumes:
  - name: my-secret-volume
    secret:
      secretName: my-secret

• As environment variables:

  env:
  - name: USERNAME
    valueFrom:
      secretKeyRef:
        name: my-secret
        key: username

Important:

• Secret data is base64 encoded.
• Consider tools like Sealed Secrets for encrypting secrets at rest.
• Never store secrets in plain text within your application code.

This document provides code examples for managing Kubernetes Secrets. It covers creating secrets from files, literals, and YAML, viewing and updating secrets, deleting secrets, and using secrets in pods as volumes and environment variables. It emphasizes encoding secret data with base64, using tools like Sealed Secrets for encryption at rest, and avoiding storing secrets in plain text within application code.

This document provides code examples for managing Kubernetes Secrets, as described in the provided article.

1. Create a Secret:

• From a file (e.g., my.key):

  kubectl create secret generic my-secret --from-file=my.key

• Using literals:

  kubectl create secret generic my-secret --from-literal=username=admin --from-literal=password=secret

• With YAML (file: secret.yaml):

  apiVersion: v1
  kind: Secret
  metadata:
    name: my-secret
  type: Opaque
  data:
    username: YWRtaW4=  # base64 encoded value of "admin"
    password: c2VjcmV0  # base64 encoded value of "secret"

  Apply with:

  kubectl apply -f secret.yaml

2. View a Secret:

kubectl get secret my-secret -o yaml

3. Update a Secret:

• Edit and apply YAML:

  1. Modify the secret.yaml file (e.g., change the password).

  2. Re-apply with:

     kubectl apply -f secret.yaml

• Use kubectl patch:

  kubectl patch secret my-secret --patch '{"data":{"password":"bmV3cGFzc3dvcmQ="}}'

  Replace bmV3cGFzc3dvcmQ= with the base64 encoded value of the new password.

4. Delete a Secret:

kubectl delete secret my-secret

5. Use a Secret in a Pod:

• Mount as a volume (in pod.yaml):

  apiVersion: v1
  kind: Pod
  metadata:
    name: my-pod
  spec:
    containers:
    - name: my-container
      image: my-image
      volumeMounts:
      - name: my-secret-volume
        mountPath: /etc/my-secret
    volumes:
    - name: my-secret-volume
      secret:
        secretName: my-secret

• As environment variables (in pod.yaml):

  apiVersion: v1
  kind: Pod
  metadata:
    name: my-pod
  spec:
    containers:
    - name: my-container
      image: my-image
      env:
      - name: USERNAME
        valueFrom:
          secretKeyRef:
            name: my-secret
            key: username

Important:

• Secret data is base64 encoded. You can encode and decode values using online tools or command-line utilities like base64.
• Consider tools like Sealed Secrets for encrypting secrets at rest.
• Never store secrets in plain text within your application code.

This provides practical examples for managing Kubernetes Secrets. Remember to adapt these examples to your specific needs and security requirements.

Security Best Practices:

• Rotation: Regularly rotate secrets to minimize the impact of a potential compromise.
• Access Control: Use Role-Based Access Control (RBAC) to restrict which users and applications can access specific secrets.
• Namespace Isolation: Store secrets in separate namespaces to further limit access and potential damage.
• Avoid Hardcoding: Never hardcode secrets directly into your application code or configuration files.
• External Secrets Management: For enhanced security, consider using external secrets management solutions that integrate with Kubernetes.

Advanced Usage:

• Secret Types: Kubernetes supports different secret types like docker-registry for storing container registry credentials.
• Image Pull Secrets: Use image pull secrets to authenticate with private container registries when pulling images for your pods.
• Templating: Use tools like Helm to manage and deploy secrets along with your application configurations.
• Secret Backups: Implement a backup and recovery strategy for your secrets to prevent data loss.

Troubleshooting:

• Decoding Secrets: Use the kubectl get secret <secret-name> -o yaml | grep <key> command to retrieve and decode a specific secret value.
• Pod Errors: Check pod logs and events for errors related to secret access or mounting.
• Permissions: Ensure that the service account used by your pods has sufficient permissions to access the required secrets.

Alternatives to Kubernetes Secrets:

• Sealed Secrets: Encrypts secrets at rest using public-key cryptography, allowing you to store them securely in Git repositories.
• HashiCorp Vault: A dedicated secrets management solution that integrates with Kubernetes and provides advanced features like secret rotation and auditing.

Remember that managing secrets effectively is crucial for the security of your Kubernetes applications. Always follow best practices and choose the right tools and strategies based on your specific needs and security requirements.

Key Points:

• Kubernetes Secrets store sensitive data in base64 encoded format.
• Use tools like Sealed Secrets for encrypting secrets at rest.
• Never hardcode secrets directly into your application code.

Kubernetes Secrets are a fundamental part of securely managing sensitive information in your Kubernetes deployments. By understanding how to create, view, update, delete, and use Secrets effectively, you can ensure your application credentials and sensitive data are stored and accessed securely. Remember to follow security best practices such as secret rotation, access control, and using tools like Sealed Secrets for enhanced security. By incorporating these practices, you can confidently deploy and manage your applications while minimizing the risks associated with sensitive data exposure.

• Managing Secrets using kubectl | Kubernetes | Creating Secret objects using kubectl command line.
• How to Securely Create, Edit, and Update Your Kubernetes Secrets | Create, retrieve, update, and delete secrets with kubectl and with a yaml manifest, consume secrets within pods and as environment variables.
• Secrets | Kubernetes | A Secret is an object that contains a small amount of sensitive data such as a password, a token, or a key. Such information might otherwise be put in a Pod specification or in a container image. Using a Secret means that you don't need to include confidential data in your application code. Because Secrets can be created independently of the Pods that use them, there is less risk of the Secret (and its data) being exposed during the workflow of creating, viewing, and editing Pods.
• Creating docker-registry secret using a YAML file - General ... | Hi Kubernauts How can I create a docker-registry secret using a yaml file? I’ve already created from CLI using kubectl of this way: kubectl create secret docker-registry regcred --docker-server=my-container-registry-url --docker-username=my-username --docker-password=my-password --docker-email=my-email But my idea is create it from a YAML file, because I want to automate this secret creation process from Helm as a pre-install process. So that I am trying to create it of this way from this ...
• Managing Secrets using Configuration File | Kubernetes | Creating Secret objects using resource configuration file.
• Mounting a Kubernetes Secret as a single file inside a Pod | Jeff ... | Jan 15, 2019 ... Jeff you might want to consider confirming this/updating your article, seems it should work for you too. ... Created a secret for a specific ...
• ConfigMaps and Secrets mounted with subPath do not update when ... | /kind bug What happened: I wanted to mount a ConfigMap and a Secret directly as a file and didn't want to mount it as a full directory, so I used subPath to do so: volumeMounts: - name: my-config m...
• How are you handling secrets in your GitOps setup? : r/kubernetes | Posted by u/MikeAnth - 46 votes and 74 comments
• bitnami-labs/sealed-secrets: A Kubernetes controller and ... - GitHub | A Kubernetes controller and tool for one-way encrypted Secrets - bitnami-labs/sealed-secrets