Flannel — Operations¶

Scope

Production deployment patterns, operational procedures, performance tuning, and troubleshooting for Flannel.

Deployment¶

Installation¶

# Apply Flannel manifest
kubectl apply -f https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml

Backend Selection¶

Backend	Overhead	Performance	Encryption	Use Case
VXLAN	Medium	Good	No	Default, most clusters
host-gw	None	Best	No	L2-adjacent nodes only
WireGuard	Low	Good	Yes	Cross-DC with encryption

// net-conf.json
{
  "Network": "10.244.0.0/16",
  "Backend": {
    "Type": "vxlan",
    "VNI": 1,
    "DirectRouting": true
  }
}

Operations¶

# Check Flannel pods
kubectl get pods -n kube-flannel

# Check subnet allocation
cat /run/flannel/subnet.env

# Check VXLAN interface
ip -d link show flannel.1

Troubleshooting¶

Issue	Diagnosis	Fix
Pod network unreachable	`ip route show`	Check flannel.1 interface, VXLAN
Subnet conflict	`/run/flannel/subnet.env`	Delete flannel.1, restart pod
flanneld crash	`kubectl logs -n kube-flannel`	Check etcd connectivity
MTU issues	`ip link show flannel.1`	Set MTU to 1450 (VXLAN overhead)