How to Secure Containers and Kubernetes in a Cloud Environment

November 27, 20234 min read

Securing containers and Kubernetes in a cloud environment is crucial to ensure the integrity, confidentiality, and availability of applications and data. Below are detailed steps and best practices.

Container Security

Image Security

  • Use Trusted Base Images: Start with minimal and secure base images from trusted sources or official repositories.
  • Scan for Vulnerabilities: Regularly use tools like Clair, Trivy, or Anchore to scan images for vulnerabilities.
  • Sign Images: Implement Docker Content Trust or Notary to sign your images to ensure they are tamper-proof.
  • Image Assurance Policies: Define and enforce policies that ensure only images that meet your security standards are deployed.

Containers Runtime Security

  • Use a Secure Container Runtime: Choose container runtimes (like containerd or CRI-O) that are focused on security.
  • Runtime Policies: Use tools like Falco to monitor container behavior at runtime and alert on suspicious activities.
  • Immutability: Deploy containers in an immutable fashion, where no changes are made to running containers.

Least Privilege Access

  • Run as Non-Root: Configure containers to run as non-root users wherever possible.
  • Limit Resources: Apply resource constraints to prevent denial-of-service attacks.
  • Capabilities and Seccomp: Drop unnecessary Linux capabilities and apply Seccomp profiles to limit system calls containers can execute.

Network Security

  • Network Policies: Define network policies to control traffic between pods/services.
  • Segmentation: Implement network segmentation to reduce the attack surface.

Kubernetes Security

Cluster Setup and Management

  • Private Clusters: Deploy to a private network that’s not publicly accessible.
  • Versioning: Ensure Kubernetes is up to date to benefit from security patches.
  • Role-Based Access Control (RBAC):
    • Define roles and responsibilities with minimum necessary permissions.
    • Regularly audit permissions and revise access controls.
  • Audit Logging: Enable audit logs to keep track of cluster events for future analysis in case of incidents.

API Server Security

  • Authentication: Use strong authentication mechanisms like OIDC or Mutual TLS.
  • Authorization: Apply least privilege via RBAC to users and applications interacting with the Kubernetes API.
  • Admission Control: Use admission controllers to enforce good practices and prevent unsafe configurations.

Node Security

  • Hardening: Apply security best practices to the host system.
  • CIS Benchmarks: Follow the CIS Kubernetes Benchmark for a systematic guide to securing your nodes.
  • Firewalls: Configure host-based firewalls (like iptables or firewalld) to control network access to nodes.

Secrets Management

  • Encryption at Rest: Ensure secrets are encrypted at rest using KMS providers.
  • Access Control: Tightly control access to secrets through RBAC.
  • Rotation and Expiry: Implement secret rotation and automatic expiry mechanisms.


  • Network Policies: Define Kubernetes network policies to control pod communications.
  • Encryption in Transit: Use TLS for data in transit between microservices.

Pod Security

  • Pod Security Policies (PSP): (Note: PSPs are deprecated from Kubernetes version 1.21, consider alternatives like OPA/Gatekeeper)
    • Define Pod Security Policies to enforce security best-practices in your pods.
  • Service Mesh: Implement a service mesh like Istio to enhance security with mTLS and fine-grained access policies.

Ongoing Security Practices

  • Continuous Scanning: Regularly scan images and running workloads for vulnerabilities.
  • Patch Management: Keep your applications and dependencies up to date with automated patch management strategies.
  • Disaster Recovery Plan: Develop and routinely test disaster recovery plans.
  • Education and Training: Train your team on Kubernetes security best practices and encourage a security-focused culture.

Securing containers and Kubernetes in the cloud requires a multi-layered approach that incorporates best practices from image creation to runtime operations. It’s essential to keep abreast of the latest security threats and update your security measures accordingly. Automation of security practices wherever possible will assist in maintaining a consistent security posture and reduce human error. Additionally, engaging in regular security audits and penetration testing can help identify potential weaknesses in the security configuration before they are exploited.