Mutual TLS Authentication Setup on Amazon EKS

Configure mutual TLS authentication for applications running on Amazon EKS

Security is a major consideration when executing containerized workloads in production. When various microservices connect within your Amazon EKS cluster, you want to make sure that each request is safe and that both parties trust one another. This is where mutual TLS (mTLS) authentication comes in.

Mutual TLS is a security approach in which both the client and the server exchange TLS certificates during the handshake. This not only encrypts communication, but also allows both parties to authenticate the other's identity. On Amazon EKS, you can configure mTLS utilizing service meshes such as AWS App Mesh or Istio, or manually using custom certificates and sidecar proxies.

Why Is mTLS Important for EKS?

• Zero-Trust Security: Every service call is validated, with no implicit trust.

• Encryption in Transit: Keeps data safe from interception between pods.

• Strong Identity Assurance: This ensures that the caller and receiver are who they claim to be.

• Compliance: Meets industry security standards (e.g., HIPAA, PCI DSS).

Steps for Configuring mTLS on Amazon EKS

1. Create a Service Mesh (Recommended)
Using a service mesh, such as AWS App Mesh or Istio, simplifies mTLS configuration.

• Install Istio or App Mesh. Add the mesh control plane to your EKS cluster.

• Enable Sidecar Injection: Set automated sidecar injection for your workloads so that Envoy proxies can handle TLS.

• Distribute Certificates: The mesh automatically manages certificate issuance and rotation via AWS Certificate Manager (ACM) or an internal CA.

• Enable mTLS Policies: Use mesh policies to enforce mTLS between services.

2. Manual mTLS Setup (without Service Mesh)
If you want a lighter approach:

• Certificate generation: Create client and server certificates with ACM PCA or OpenSSL.

• Mount Certificates: Keep them secure in AWS Secrets Manager or Kubernetes Secrets and mount them as volumes.

• Configure Applications: Update app settings to use TLS certificates for both inbound and outbound connection.

• Implement Certificate Rotation: To replace expiring certificates, automate updates with a CI/CD pipeline or cron job.

Benefits After Implementation

Configuring mTLS ensures that no service in your EKS cluster impersonates another. This significantly lowers the attack surface, protects your traffic, and meets regulatory requirements. With automated certificate rotation, you can maintain robust security without causing operational issues.

FAQs

Q1: Do I need a service mesh to use mTLS with EKS?

No, however a service mesh such as AWS App Mesh or Istio makes the process easier by automating certificate distribution and rotation.

Q2: How frequently should I rotate certificates?

The industry standard is every 90 days or fewer. Using ACM PCA or mesh-managed certificates ensures automatic and seamless rotation.

Q3: Does mTLS increase latency?

Yes, TLS handshakes add a tiny overhead, but it is minimal for most applications. Security gains outweigh performance costs.

Q4: Can I enable mTLS exclusively for certain services?

Yes. Rather than imposing cluster-wide mTLS, you can configure namespace- or service-specific mTLS policies.

Q5: What happens if a service does not provide a valid certificate?

With stringent mTLS enabled, the connection is refused to prevent illegal access.