Install Flannel¶

Script¶

Run directly (without the dispatcher):

curl -fsSL https://raw.githubusercontent.com/ibtisam-iq/silver-stack/main/scripts/kubernetes/cni/install-flannel.sh | sudo bash

Defaults¶

Installation Phases¶

Phase 1 — Cluster Access Verification¶

Sources ensure_kubeconfig, then confirms the cluster is reachable:

kubectl get ns kube-system

Exits immediately if the cluster is not accessible.

Phase 2 — Pod CIDR Detection¶

Reads the Pod CIDR from the kubeadm-config ConfigMap — same approach as the Calico installer. The cluster is the source of truth:

kubectl -n kube-system get cm kubeadm-config \
  -o jsonpath='{.data.ClusterConfiguration}' | grep podSubnet

Exits with an error if podSubnet cannot be parsed.

Phase 3 — Workspace Preparation¶

rm -rf /tmp/flannel-install && mkdir -p /tmp/flannel-install

Phase 4 — Download Flannel Manifest¶

Downloads kube-flannel.yml from the official Flannel latest release:

curl -fsSL https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml \
  -o /tmp/flannel-install/kube-flannel.yml

Always pulls the latest release — no version pinning.

Phase 5 — Patch Pod CIDR¶

A single sed -i substitution patches the Network field in the Flannel ConfigMap inside the manifest before it is applied:

sed -i 's|"Network": ".*"|"Network": "<detected-pod-cidr>"|' kube-flannel.yml

This ensures Flannel uses the same CIDR that was configured during kubeadm init.

Phase 6 — Apply Flannel Manifest¶

kubectl apply -f /tmp/flannel-install/kube-flannel.yml

This creates the kube-flannel namespace, ServiceAccount, ClusterRole, ConfigMap, and DaemonSet in a single apply.

Phase 7 — Stabilization Wait¶

Two checks run in sequence:

1. Polls for kube-flannel namespace creation (up to 120s, 2s interval)
2. Polls for DaemonSet readiness (up to 300s, 15s interval):

kubectl -n kube-flannel rollout status daemonset/kube-flannel-ds --timeout=5s

Prints elapsed time every 15 seconds. Exits with error if the DaemonSet is not ready within 300 seconds.

Phase 8 — Verification¶

kubectl -n kube-flannel get pods -l app=flannel

Confirms Flannel pods exist after install. A final ok banner is printed on success.

Post-Install Checks¶

# All nodes should now show Ready
kubectl get nodes

# Flannel pods should be Running
kubectl -n kube-flannel get pods

# Flannel DaemonSet status
kubectl -n kube-flannel get ds kube-flannel-ds

Flannel vs Calico — Quick Reference¶

Troubleshooting¶