I have a kubernetes cluster (v1.10) and flannel as cni. Using the default settings, the setup works fine (using kubeadm) but a pod cannot connect to itself via service IP.
Tried setting hairpin-mode as "promiscuous-bridge" but kubelet complains:
Hairpin mode set to "promiscuous-bridge" but kubenet is not enabled, falling back to "hairpin-veth"Not sure what's going on. Went through this https://kubernetes.io/docs/tasks/debug-application-cluster/debug-service/#a-pod-cannot-reach-itself-via-service-ip but no help. Any pointers ?
The default flannel configuration does not set HairpinMode to true.
https://raw.githubusercontent.com/coreos/flannel/v0.9.1/Documentation/kube-flannel.yml
Setting hairpinMode to true in flannel config resolved the issue. The config change is as below:
kind: ConfigMap
apiVersion: v1
metadata:
name: kube-flannel-cfg
namespace: kube-system
labels:
tier: node
app: flannel
data:
cni-conf.json: |
{
"name": "cbr0",
"type": "flannel",
"delegate": {
"hairpinMode": true,
"isDefaultGateway": true
}
}
net-conf.json: |
{
"Network": "10.244.0.0/16",
"Backend": {
"Type": "vxlan"
}
}
Complete flannel config is here:
Instead of the default kubectl command to apply flannel cni use following command:
kubectl apply -f https://gist.githubusercontent.com/phagunbaya/2a53519a9427ba0623244f1680a5b5ff/raw/13ada0d6dd92388c8c5aae93bfb1ccaf9c79f60b/flannel-0.9.1.yamlIn my case the issue was not disabling firewalld service as mentioned below. My core-dns pods kept crashing with error connect - no route to host
https://github.com/rancher/rancher/issues/6139
Run the below commands on each of your nodes as mentioned