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KubeEdge: Multus Environment Variable Injection

KubeEdge EdgeCore injects empty KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT environment variables into all containers running on edge nodes. Because the last value in the environment wins, any values set in the pod spec are overridden by the empty KubeEdge-injected ones. Multus thin_entrypoint reads these variables to generate its kubeconfig, producing an invalid server: https://[]: entry that causes the pod to crash.

How It Works in This Testbed

The edge Multus DaemonSet uses static config mode instead of auto mode. A kubeconfig is written to /var/lib/multus/multus.kubeconfig by Ansible before the DaemonSet is deployed. This path is outside /etc/cni/net.d, so thin_entrypoint does not attempt to regenerate it. The conflist references the kubeconfig by absolute path.

The worker DaemonSet uses auto mode without issues, since K3s does not inject environment variables.

Implementation

  • Edge conflist template: ansible/phases/04-overlay-network/roles/multus_install/templates/00-multus-edge.conflist.j2
  • Kubeconfig creation and DaemonSet deployment: ansible/phases/04-overlay-network/roles/multus_install/tasks/main.yml