How To Manage Kubernetes Secrets ?

Most applications deployed through Kubernetes require access to databases, services, and other resources located externally. The easiest way to manage the login information necessary to access those resources is using Kubernetes secrets. Secrets help organize and distribute sensitive information across a cluster.

What are Kubernetes Secrets?

A Kubernetes secret is an object storing sensitive pieces of data such as usernames, passwords, tokens, and keys. Secrets are created by the system during an app installation or by users whenever they need to store sensitive information and make it available to a pod.

If passwords, tokens, or keys were simply part of a pod definition or container image, they could be accidentally exposed during Kubernetes operations. Therefore, the most important function of the secret is to prevent accidental exposure of the information stored in it while at the same time making it available wherever the user needs it.

Types of Secrets

Kubernetes supports several types of Secrets, each designed to handle different use cases and data formats.

When creating a Secret, you can specify its type using the type field of the Secret resource, or certain equivalent kubectl command line flags.

Kubernetes provides several built-in types for some common usage scenarios. Here are the common types of Kubernetes Secrets:

1. Opaque Secrets: Opaque Secrets are the most generic type of Kubernetes Secrets. They can store any arbitrary data as key-value pairs. This makes them suitable for storing various types of sensitive information, such as passwords, API keys, or configuration files.

2. Service Account Tokens: Every pod in Kubernetes is associated with a Service Account, and a token is automatically mounted into the pod, allowing it to authenticate with the Kubernetes API server.

3. Docker Registry Secrets: Docker Registry Secrets are used to store authentication information for accessing private Docker registries.

4. SSH Secrets: SSH Secrets are used for storing SSH keys.

5. TLS Secrets: Used for storing SSL/TLS certificates and private keys.

These examples demonstrate how to create different types of Kubernetes secrets. You can adapt them to your specific use cases, ensuring secure handling of sensitive information within your Kubernetes deployments.

Managing Kubernetes Secrets

1. Creating Secret:

You can create secrets manually or use the ‘kubectl create secret’ command to create them. The create secret command can create secrets from string literals, or files containing the values. If we have our database credentials loaded into files named username.txt and password.txt, then we could load them into the cluster’s secret store with the following command.

kubectl create secret generic db-credentials --fromfile=./username.txt --from-file=./password.txt

This command creates a secret named ‘db-credentials’ in the secret store. The system should respond with a secret “db-credentials” created response.

Once you have created the secret object, you can add it to the container as volume attached to the pod, or you can load the values into environment variables when initializing a new container in the pod. Let’s look at an example configuration that includes the secrets as a volume on the pod.

Assuming that you used the original file names to load the database credentials into the secrets object and attached the secrets into a volume named secrets, the credentials could now be accessed at /etc/secrets/username and /etc/secrets/password.

2. Decoding Secret:

To view the data stored in a Secret, you can use the ‘kubectl get secret’ command with the –output flag set to jsonpath.

kubectl get secret my-secret --output jsonpath='{.data}'

• You can check if the Secret is created or not by giving below command.

kubectl get secrets

This command will show us the list of secrets-their names, type and number of data values.

3. Updating Secret:

To update an existing Secret, you can use the ‘kubectl create secret’ command again. If you want to update the existing Secret in-place, you can use the ‘kubectl patch’ command.

kubectl patch secret my-secret

4. Deleting Secret:

You can delete a Secret using the ‘kubectl delete secret’ command followed by the Secret name.

kubectl delete secret my-secret

By following these steps, you can effectively manage Kubernetes Secrets in your cluster.

Best Practices for Managing Kubernetes Secrets

Secrets, like keys, passwords, tokens, and other configuration values, must be stored correctly. If our Kubernetes cluster is compromised, the Secrets must remain secure.

Here are some techniques to help us keep Kubernetes Secrets safe:

• Encrypt Data in Transit and at Rest: Kubernetes does not safely store or transmit secrets by default. Hence, it is crucial to have a structure that encrypts secrets in transit with end-to-end TLS encryption, and a solution that stores secrets in an encrypted form.
• Use a centralized Secrets store for easy management: When we store secrets in many places, securing them becomes challenging — especially when we must manage Secrets in multiple clusters, or if we have a mix of private and public key pairs. Without a centralized Secrets management system, Secrets are sprawled across locations, increasing the attack surface for unauthorized users.
• Encrypt etcd data: One way to harden the security of etcd data is to encrypt Secrets before storing them. We should use an encryption provider, such as a Key Management Service (KMS), to store our keys and Secrets. It’s good to note that most managed Kubernetes providers encrypt etcd Secrets storage by default when a cluster is created, which helps keep our etcd data safe.
• Have an Audit Log: It’s a good idea to know your secrets activity. In the event of a breach, an audit log provides visibility and helps you assess the incident, including whether the compromise was intentional, the affected area and other investigative steps.

Updating and Rotating Secrets

Updating and rotating secrets are essential practices in maintaining the security of your applications and systems. Secrets, such as passwords, cryptographic keys, and API tokens, need to be regularly updated and rotated to minimize the risk of unauthorized access and potential security breaches.

Here are some key considerations and best practices:

1. Updating Secrets:

• Purpose: Updating secrets is necessary when there’s a need to modify the sensitive information stored in a secret. This could include changes in passwords, API keys, certificates, or any other confidential data.
• Process: To update a secret, you typically need to create a new version of the secret with the updated information. Once the new version is created, you may need to update your applications or services to use the latest version of the secret.
• Example: If you need to change the password for a database connection stored in a secret, you create a new version of the secret with the updated password and then update the applications to use the new secret.

2. Rotating Secrets:

• Purpose: Rotating secrets is a proactive security measure to regularly change sensitive information, reducing the impact of potential security breaches. This is crucial for minimizing the exposure window of credentials or keys.
• Process: Rotating secrets involves creating a new version of the secret with fresh credentials or keys while keeping the previous version active for a transitional period. Once applications are updated to use the new version, the old version can be deleted.
• Example: If you have an API key stored in a secret and you rotate it, you create a new version with a new API key. Applications are then updated to use the new key, and after a transition period, the old version is removed.

Best Practices for Updating and Rotating Secrets:

• Automation: Utilize automation tools to facilitate the updating and rotating of secrets, ensuring consistency and reducing manual errors.
• Regular Schedule: Establish a regular schedule for secret rotation to maintain a proactive security posture.
• Audit Logging: Implement audit logging to track changes to secrets, providing visibility into who made changes and when.
• Versioning: Leverage versioning features in secret management to maintain a history of changes and easily roll back if needed.

Examples of Kubernetes Secrets in Real-World Scenarios

Here are some examples of how Kubernetes Secrets can be used in real-world scenarios:

1. Docker registry credentials: Cluster nodes need credentials to pull private Docker images. These registry usernames/passwords can be stored in a Secret that only the node Kubernetes daemons can access.
2. Cloud metadata: Sensitive metadata like access keys for cloud providers can be passed to pods via Secrets instead of command line arguments or pod configs.
3. API Keys and Tokens: When integrating with external APIs or services, applications often require API keys or tokens for authentication. Storing these credentials in Kubernetes Secrets helps manage and rotate them easily without exposing them in source code or configuration files.
4. SSL/TLS Certificates: Applications often require SSL/TLS certificates for secure communication. Kubernetes Secrets can store these certificates, making it easy to manage and update them without the need to redeploy the entire application.
5. Git credentials: For cloning private git repositories inside pods, git usernames/tokens can be stored as a Secret. This avoids hardcoding git credentials in pod configs.
6. Configuration Files: Some applications use configuration files that contain sensitive information. Kubernetes Secrets can be mounted as files in the application’s containers, allowing secure access to sensitive configuration data without exposing it in environment variables.
7. Database Credentials: In a microservices architecture, various services may need to connect to databases. Kubernetes Secrets can store database connection strings, usernames, and passwords securely. This ensures that sensitive information is not exposed in configuration files or environment variables.
8. Encryption Keys: For applications that require encryption, storing encryption keys in Kubernetes Secrets ensures that sensitive data is protected. This is crucial for securing data at rest or in transit.

Conclusion

In conclusion, managing Kubernetes secrets is an essential aspect of maintaining robust security practices within a cluster environment. Employing encryption, access control mechanisms, regular rotation, and monitoring tools are fundamental steps in securing Kubernetes secrets. By prioritizing the proper management of secrets, organizations can significantly reduce the risk of potential security threats and enhance the overall integrity of their Kubernetes infrastructure.

Kubernetes Secrets – FAQ’s

Should I commit secrets to source code repositories?

No, never commit secrets to source code repos. Use a secure secrets management approach that keeps them out of repositories.

What are best practices for managing secrets?

Rotate frequently, restrict access, encrypt, use external stores, delete completely when done, audit access, use namespaces to partition secrets, etc.

How do I prevent accidental exposure of Secrets in logs or repositories?

Employ encryption mechanisms for logs or consider using Secret scanning tools to detect and remediate accidental exposure in code repositories.