Tip: Can't find docker networking namespace via ip netns list

Symptom:

    In ubuntu, we start a docker container, try to find docker networking namespace via "ip netns list". The output is empty.

Reason:

   The docker by default , it records netns on /var/run/docker/netns. While "ip netns list" is checking /var/run/netns

Workaround:  

 stop all containers , rm -rf /var/run/netns,  ln -s /var/run/docker/netns  /var/run/netns

Tip:

To find netns id of container use

docker ps ---> find container ID

docker inspect <contain ID> |grep netns

Tip: Bind Error when running multiple schedulers in K8S

Error details: 

I0530 09:25:29.097683       1 serving.go:331] Generated self-signed cert in-memory

failed to create listener: failed to listen on 127.0.0.1:10259: listen tcp 127.0.0.1:10259: bind: address already in use

Reason:

     It's due to the default scheduler is running on the same node. We can move the 2nd scheduler to another node to fix this.