Lab 11: Provisioning Pod Network Routes¶

This is a fork of the original "Kubernetes the hard way" originally written by Kelsey Hightower (GitHub: kelseyhightower). Unlike the original that bases itself on Debian like distributions for the ARM64 architecture, this fork targets Enterprise Linux distributions such as Rocky Linux running on x86_64 architecture.

Pods scheduled to a node receive an IP address from the node's Pod CIDR range. At this point pods cannot communicate with other pods running on different nodes due to missing network routes.

In this lab you will create a route for each worker node that maps the node's Pod CIDR range to the node's internal IP address.

There are other ways to implement the Kubernetes networking model.

The Routing Table¶

In this section you will gather the information required to create routes in the kubernetes-the-hard-way VPC network.

Print the internal IP address and Pod CIDR range for each worker instance:

{
  SERVER_IP=$(grep server machines.txt | cut -d " " -f 1)
  NODE_0_IP=$(grep node-0 machines.txt | cut -d " " -f 1)
  NODE_0_SUBNET=$(grep node-0 machines.txt | cut -d " " -f 5)
  NODE_1_IP=$(grep node-1 machines.txt | cut -d " " -f 1)
  NODE_1_SUBNET=$(grep node-1 machines.txt | cut -d " " -f 5)
}

ssh root@server <<EOF
  ip route add ${NODE_0_SUBNET} via ${NODE_0_IP}
  ip route add ${NODE_1_SUBNET} via ${NODE_1_IP}
EOF

ssh root@node-0 <<EOF
  ip route add ${NODE_1_SUBNET} via ${NODE_1_IP}
EOF

ssh root@node-1 <<EOF
  ip route add ${NODE_0_SUBNET} via ${NODE_0_IP}
EOF

Verification¶

ssh root@server ip route

default via XXX.XXX.XXX.XXX dev ens160 
10.200.0.0/24 via XXX.XXX.XXX.XXX dev ens160 
10.200.1.0/24 via XXX.XXX.XXX.XXX dev ens160 
XXX.XXX.XXX.0/24 dev ens160 proto kernel scope link src XXX.XXX.XXX.XXX

ssh root@node-0 ip route

default via XXX.XXX.XXX.XXX dev ens160 
10.200.1.0/24 via XXX.XXX.XXX.XXX dev ens160 
XXX.XXX.XXX.0/24 dev ens160 proto kernel scope link src XXX.XXX.XXX.XXX

ssh root@node-1 ip route

default via XXX.XXX.XXX.XXX dev ens160 
10.200.0.0/24 via XXX.XXX.XXX.XXX dev ens160 
XXX.XXX.XXX.0/24 dev ens160 proto kernel scope link src XXX.XXX.XXX.XXX

Next: Smoke Test

Author: Wale Soyinka

Contributors: Steven Spencer