Kubernetes IPAM Plugin

A CNI Ipam plugin that uses a CRD for allocating IPs for a given network.

When an ip is requested, the plugin retrieves the configured IPPool from the kubernetes API, an IP is allocated from the pool as follows:

• If an IP is already assigned to a pod with a matching name/namespace tuple, that ip is reassigned (any pod that's named the same will get the same IP when relaunched)
• Otherwise an IP is chosen randomly
  • If the chosen IP is available it is marked as belonging to this pod in the pool and assigned.
  • If the chosen IP is assigned, we check to see if the pod that has claimed it is still running.
    • If the pod is no longer running, the IP is reclaimed by us.
    • If the pod is running a new IP is chosen and the process is repeated until an ip is assigned.

Example IPPool JSON:

{
    "apiVersion":"ipam.k8s.io/v1alpha1",
    "kind":"IPPool",
    "metadata":{
        "name":"ippool"
    },
    "spec":{
        "ipPoolSubs":[
            {
                "range":"10.19.120.0-10.19.123.254/22",
                "reservedRanges":[
                    "10.19.122.230-10.19.122.255/22"
                ],
                "netmaskBits":22,
                "gateway":"10.19.123.254"
            }
        ]
    }
}