kubernetes-the-hard-way/docs/11-pod-network-routes.md

Provisioning Pod Network Routes

Pods scheduled to a node receive an IP address from the node's Pod CIDR range. At this point pods can not 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:

{
  NODE_0_IP=$(grep node01 machines.txt | cut -d " " -f 1)
  NODE_0_SUBNET=$(grep node01 machines.txt | cut -d " " -f 4)
  NODE_1_IP=$(grep node02 machines.txt | cut -d " " -f 1)
  NODE_1_SUBNET=$(grep node02 machines.txt | cut -d " " -f 4)
}

ssh vagrant@controlplane <<EOF
  sudo ip route add ${NODE_0_SUBNET} via ${NODE_0_IP}
  sudo ip route add ${NODE_1_SUBNET} via ${NODE_1_IP}
EOF

ssh vagrant@node01 <<EOF
  sudo ip route add ${NODE_1_SUBNET} via ${NODE_1_IP}
EOF

ssh vagrant@node02 <<EOF
  sudo ip route add ${NODE_0_SUBNET} via ${NODE_0_IP}
EOF

Verification

ssh vagrant@controlplane 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 vagrant@node01 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 vagrant@node02 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

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