Checking iptables filtering for bridge networking on Ubuntu (for Kubernetes setup)

If you’re installing and configuring a Kubernetes cluster on bare metal or in a VM yourself, one of the install steps using kubeadm says to check iptables filtering for bridge networking, but it doesn’t exactly say how to do this per distro.

The setting required is:

net.bridge.bridge-nf-call-iptables=1

There are specific steps in the kubadm docs above for RHEL/CentOS to add this setting. For Ubuntu it seems this is set by default, but you can confirm by:

sysctl net.bridge.bridge-nf-call-iptables

and the expected setting is 1:

net.bridge.bridge-nf-call-iptables = 1

It seems on Ubuntu 16.04 server this is set to 1 by default, but if it’s 0, you can edit this property in /etc/sysctl.conf

kubernetes: switching kubectl contexts

Info about your currently configured clusters and contexts referring to each of these contexts is stored in ~/.kube/config . You can browse this into with:

kubectl config view

For contexts, scroll down to the contexts section.

For your currently configured context:

 kubectl config current-context

To switch to another context:

kubectl config use-context contextname

Related info on kubectl: https://kubernetes.io/docs/tasks/access-application-cluster/configure-access-multiple-clusters/