feat(network): add support for Cilium WireGuard Strict Mode (Zero-Trust)

[aveljkovic]

Description
This PR implements first-class support for Cilium WireGuard Strict Mode, enabling transparent "Zero-Trust" networking. When enabled, this feature encrypts ALL traffic (pod-to-pod and node-to-node) at the kernel level using WireGuard, blocking any unencrypted traffic.

This addresses the need for high-security, compliant cluster deployments directly via Kubespray inventory variables.

Changes

• Defaults (roles/network_plugin/cilium/defaults/main.yml): Added cilium_encryption_strict_mode (default: false) to ensure backward compatibility.
• Templates (templates/values.yaml.j2): Updated logic to automatically configure encryption.strictMode and encryption.nodeEncryption when the variable is enabled.
• Scripts: Added roles/network_plugin/cilium/files/verify-encryption.sh, a helper script to audit the encryption status post-deployment.
• Documentation: Updated docs/CNI/cilium.md with a guide on enabling Strict Mode and verifying zero-trust status.

How to Test

1. Enable the feature in your inventory:

   cilium_encryption_strict_mode: true

2. Deploy the cluster.
3. Run the included verification script:

   ./roles/network_plugin/cilium/files/verify-encryption.sh

4. Manual Verification:
   Exec into a Cilium pod and check for the WireGuard interface:

   kubectl -n kube-system exec ds/cilium -- cilium status | grep Encryption
   # Output should show: Encryption: WireGuard (Strict Mode)

Checklist

• Ansible playbooks successfully run.
• Feature is disabled by default (Backward Compatible).
• Documentation updated.
• Validation checks added for Kernel requirements.

Related Issue
(None)

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The committers listed above are authorized under a signed CLA.

• ✅ login: aveljkovic / name: Aleksandar Veljković (452a9b0)

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[aveljkovic]

@VannTen @mzaian Just wanted to check in and see if there are any updates or additional feedback on my PR. Let me know if there’s anything I can do to help move this forward. Thanks!

[bbaassssiiee]

Why adding all this code for three vars?

cilium_encryption_enabled: true
cilium_encryption_type: "wireguard"
cilium_encryption_node_encryption: true