kubernetes-the-hard-way/configs/10-bridge.conf

{
  "cniVersion": "1.0.0",
  "name": "crio",
  "plugins": [
    {
      "type": "bridge",
      "bridge": "cni0",
      "isGateway": true,
      "ipMasq": true,
      "hairpinMode": true,
      "ipam": {
        "type": "host-local",
        "routes": [
            { "dst": "0.0.0.0/0" },
            { "dst": "::/0" }
        ],
        "ranges": [
            [{ "subnet": "IPV4_SUBNET" }],
            [{ "subnet": "IPV6_SUBNET" }]
        ]
      }
    }
  ]
}