While many organizations have successfully adopted containers and the container orchestration framework Kubernetes, it is worth noting that many enterprises feel challenged with running containers in production.
Various reasons contribute to the hesitation. Without prior experience, the very idea of transitioning to containerization can be daunting for DevOps teams. After all, the learning curve associated with properly configuring Kubernetes cluster components can be steep.
When containerization is adopted for a completely new application that is ideally cloud-native, it is a lot easier to transition over. But for enterprises that are still adjusting to their cloud adoption journey, deciding to move containers to production is a massive step.
For one, refactoring or redesigning legacy applications to be container-friendly requires substantial effort and may disrupt existing workflows. Another issue is operational readiness. Running containers at scale demands a robust operational infrastructure, where enterprises must invest in everything from container registries and CI/CD pipelines to automation tools and appropriate monitoring solutions. And most importantly, containers share the same host operating system kernel, which raises security concerns. A compromised container can create a potential risk of unauthorized access to the host system or other containers running on the same host.
The Kubernetes Cluster
A cluster is central to the basic framework of Kubernetes. If you’re running Kubernetes, you’re running at least one cluster, which can be compared to the central nervous system for your application(s). In a Kubernetes cluster, the control plane controls nodes, nodes control pods, pods control containers, and containers control applications. Regarding security, Kubernetes provides a foundation for securing containerized applications. However, Kubernetes clusters are not secure by default.
5 Kubernetes Cluster Security Best Practices
When you are ready to deploy your containers to production, secure the clusters by taking the following measures.
- Update your Kubernetes cluster regularly: Your Kubernetes cluster must be updated on a regular basis in order to leverage new features, bug fixes, security patches, and performance improvements provided by newer versions of Kubernetes. To upgrade your cluster, first, determine the recommended upgrade path based on your current Kubernetes version. Some upgrades may require stepping through intermediate versions to ensure a smooth transition.
Start by upgrading the control plane components by following the specific instructions provided by the Kubernetes distribution you're using. Once the control plane is upgraded, proceed to upgrade the worker nodes. This can be done gradually in a rolling fashion using the Kubernetes command line tool, Kubectl, to ensure zero to minimal downtime to running workloads. It is important to verify the health and functionality of the cluster, ensuring that workloads run as expected and that all cluster components communicate properly. Lastly, make sure to test and validate any add-ons, plugins, or custom configurations in the upgraded cluster to ensure they are compatible and functioning correctly.
- Limit access to the Kubernetes API: Limiting access to the Kubernetes API is crucial for protecting your cluster from unauthorized access, data breaches, and potential attacks. Restricting access also meets regulatory and compliance requirements, ensuring only authorized users and systems can perform admin actions on the cluster. By limiting API access, you maintain necessary control over cluster resources, configurations, and sensitive data thereby blocking accidental or malicious modifications to critical components of your cluster.
Limit API access by requiring authentication for all API requests using mechanisms such as client certificates, bearer tokens, or external identity providers like OAuth or LDAP. Implement Role-Based Access Control (RBAC) using the “Principle of Least Privilege” to define roles and grant or deny permissions to users and service accounts. Applying fine-grained control with RBAC over user and service account permissions is essential to ensuring that only authorized entities can perform specific role-based actions on cluster resources.
- Address container image security in a Kubernetes cluster: Container images serve as building blocks for running applications in Kubernetes. Compromised or malicious container images can introduce malware into the cluster. Container images also contain software vulnerabilities due to outdated packages, misconfigurations, or other known security issues. Running such images in the cluster can lead to unauthorized access and a major compromise of cluster resources and other containers.
It is important to incorporate only container images from trusted sources. Perform image scanning as part of your CI/CD pipeline to ensure images are free from vulnerabilities prior to deployment. Image signing and integrity verification mechanisms also play a pivotal role in detecting unauthorized modifications to images. Regularly patching container images for security issues, continuously monitoring and re-scanning images as new threats emerge, and using authentication, access control, and encryption mechanisms are some other best practices that prevent unauthorized access and tampering with container images.
- Manage Kubernetes secrets: Secrets management is crucial for maintaining the security of the Kubernetes cluster because secrets are used to store sensitive information such as API keys, passwords, tokens, and database credentials. Secrets management mechanisms facilitate encrypted communication, provide granular role-based access control to secrets, and offer an automated rotation of credentials, reducing the risk of prolonged exposure due to forgotten or neglected secrets. It is best to integrate secrets management into the CI/CD pipeline, allowing secure and automated deployment of applications without exposing sensitive information. This ensures that secrets are not hardcoded in application configurations or source code repositories, reducing the risk of accidental exposure.
- Implement robust logging and monitoring practices: By doing so, organizations improve their threat detection and incidence response capabilities. By analyzing logs and monitoring metrics, security teams are able to detect and respond to security threats faster while maintaining a proactive and compliant security posture. Log and monitor all cluster components including nodes, pods, containers, and the control plane. Watch for anomalies or deviations from normal behavior that are indicators of compromise. Regular security audits and reviews of monitoring data will help ensure adherence to security best practices.
The best practices discussed above are necessary to maintain a secure Kubernetes cluster and make the task of launching clusters in production more failsafe.
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