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:

for instance in worker-0 worker-1 worker-2; do
  yc compute instance get --full ${instance} \
  	--format json | jq -r '[.network_interfaces[0].primary_v4_address.address,.metadata."pod-cidr"] | join(" ")'
done

output

10.240.0.20 10.200.0.0/24
10.240.0.21 10.200.1.0/24
10.240.0.22 10.200.2.0/24

Routes

Create route table with network routes for each worker instance:

yc vpc route-table create --name=kubernetes-route-table \
  --network-name=kubernetes-the-hard-way \
  --route destination=10.200.0.0/24,next-hop=10.240.0.20 \
  --route destination=10.200.1.0/24,next-hop=10.240.0.21 \
  --route destination=10.200.2.0/24,next-hop=10.240.0.22

List the routes in the kubernetes-route-table route table:

yc vpc route-table get kubernetes-route-table --format json | jq .static_routes

output

[
  {
    "destination_prefix": "10.200.0.0/24",
    "next_hop_address": "10.240.0.20"
  },
  {
    "destination_prefix": "10.200.1.0/24",
    "next_hop_address": "10.240.0.21"
  },
  {
    "destination_prefix": "10.200.2.0/24",
    "next_hop_address": "10.240.0.22"
  }
]

Link the routing table to one of the subnets

yc vpc subnet update kubernetes --route-table-name kubernetes-route-table

Next: Deploying the DNS Cluster Add-on