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How to use as Kubernetes CNI plugin

To run as Kubernetes CNI plugin, we need to run four components: sartd controller, sartd agent, sartd bgp and sartd fib.

controller runs as Deployment. And agent, bgp and fib run as DaemonSet.

To perform as CNI plugin, all components must run in host network namespace.

To know sart's CRDs, please see design #Kubernetes and design #CNI.

To work CNI well, we need to configure BGP speakers on nodes. Please see Kubernetes BGP configurations.

Address pools

To assign IP addresses to pods, we have to create address pools. We can create multiple pools in a cluster.

The type field specifies for which use the address pool is to be used. For pods, we have to set type: pod.

apiVersion: sart.terassyi.net/v1alpha2
kind: AddressPool
metadata:
  name: default-pod-pool
spec:
  cidr: 10.1.0.0/24
  type: pod
  allocType: bit
  blockSize: 29
  autoAssign: true

cidr is the subnet of assignable addresses for pods.

allocType specifies a method how to pick an address from a pool. We can only use bit.

Bit allocator type choose the address with the lowest number. For example, 10.0.0.1 and 10.0.0.10 are assignable, the bit allocator always chooses 10.0.0.1.

blockSize is used to divide the address pool into AddressBlocks. AddressBlock for pods is associated with a node and it is requested to create via a BlockRequest resource. Each block requests its cidr based on this value.

In this example, the cidr of one address block is 10.1.0.0/29 and another is 10.1.0.8/29.

autoAssign specifies its pool is used as default pool. If autoAssign is true, we can omit specifying the name of the pool in the annotation(described below). We cannot create multiple auto assignable pools in each type.

Please note that we cannot change AddressPool's spec fields except for autoAssign once it is created.

Basic usage

Once creating AddressPools, we can create some pods same as using other CNI plugins. When allocating from the auto assignable pool, there is nothing to do any other special procedure.

Choosing AddressPool

Sart CNI can create multiple pools for pods. To use the pool that is not auto assignable pool, we should add an annotation named sart.terassyi.net/addresspool to the namespace in which its pod exist or to the pod directly.