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:

  1. for instance in worker-0 worker-1 worker-2; do
  2. gcloud compute instances describe ${instance} \
  3. --format 'value[separator=" "](networkInterfaces[0].networkIP,metadata.items[0].value)'
  4. done

output

  1. 10.240.0.20 10.200.0.0/24
  2. 10.240.0.21 10.200.1.0/24
  3. 10.240.0.22 10.200.2.0/24

Routes

Create network routes for each worker instance:

  1. for i in 0 1 2; do
  2. gcloud compute routes create kubernetes-route-10-200-${i}-0-24 \
  3. --network kubernetes-the-hard-way \
  4. --next-hop-address 10.240.0.2${i} \
  5. --destination-range 10.200.${i}.0/24
  6. done

List the routes in the kubernetes-the-hard-way VPC network:

  1. gcloud compute routes list --filter "network: kubernetes-the-hard-way"

output

  1. NAME NETWORK DEST_RANGE NEXT_HOP PRIORITY
  2. default-route-1606ba68df692422 kubernetes-the-hard-way 10.240.0.0/24 kubernetes-the-hard-way 0
  3. default-route-615e3652a8b74e4d kubernetes-the-hard-way 0.0.0.0/0 default-internet-gateway 1000
  4. kubernetes-route-10-200-0-0-24 kubernetes-the-hard-way 10.200.0.0/24 10.240.0.20 1000
  5. kubernetes-route-10-200-1-0-24 kubernetes-the-hard-way 10.200.1.0/24 10.240.0.21 1000
  6. kubernetes-route-10-200-2-0-24 kubernetes-the-hard-way 10.200.2.0/24 10.240.0.22 1000

Next: Deploying the DNS Cluster Add-on