What happens when a pod runs - namespace

apiVersion: v1
kind: Pod
metadata:
  name: shared-namespace
spec:
  containers:
    - name: p1
      image: busybox
      command: ['/bin/sh', '-c', 'sleep 10000']
    - name: p2
      image: nginx

Commands

ip netns list

how to check pause container

kubectl run nginx --image=nginx
lsns | grep nginx

copy the process IP from above and run

lsns -p <pid>

check the network namespace (this gives list of all network namespaces)

ls -lt /var/run/netns

exec into the namespace or into the pod to see the IP links

ip netns exec <namespace> ip link
kubectl exec -it shared-namespace -- ip addr #run this on controlplane

Now you will see eth@9 -> after @ there will be a number and you can then search its corresponding link on the node using ip link | grep -A1 ^9 you will be able to see the same network namespace after link These are the veth pairs or based on the CNI

===========================

1. List all network interfaces on the host:

   ip link show

2. List network namespaces:

   sudo ip netns list

3. Inspect network interfaces within a specific namespace:

   Replace <namespace> with the actual namespace ID (e.g., cni-6bbf75c3-3284-407a-5869-90772afb5472).

   sudo ip netns exec <namespace> ip link

4. Find veth pairs on the host:

   ip link show | grep cali

5. Verify the veth pair connection:

   Replace <interface> with the actual veth interface name (e.g., caliede2c6f02d9).

   sudo ethtool -S <interface>

Example Workflow

1. List all interfaces:

   ip link show

2. List network namespaces:

   sudo ip netns list

3. Inspect network interfaces within the namespace cni-6bbf75c3-3284-407a-5869-90772afb5472:

   sudo ip netns exec cni-6bbf75c3-3284-407a-5869-90772afb5472 ip link

4. Find veth pairs on the host:

   ip link show | grep cali

5. Verify the veth pair connection for interface caliede2c6f02d9:

   sudo ethtool -S caliede2c6f02d9

These commands will help you identify the network interfaces and veth pairs created by the CNI plugin, and inspect the network configuration for your Pods.