CNI fiddling with 6rd/teredo/6to4

cni.sh

# n.b.: nodes are in 172.18.0.0/16

# hash subnet range with sha256 -> first 10 digit for prefix
hash_prefix=$(ip r | grep -E "\/[0-9]+ dev eth0" | cut -d' ' -f1 | sha256sum | head -c 10)
# prepend with fd for unique local address predix for 6rd routing
rd_prefix="fd${hash_prefix}"
# add colons between each 4 hex chars
rd_prefix_formatted=$(echo "${rd_prefix}" | fold -w4 | paste -sd:)
local_addr=$(ip a show dev eth0 | grep -E 'inet ' | cut -d' ' -f6 | cut -d'/' -f1)
# get local IPv4 subnet as XX.XX.XX.XX/XX
local_subnet=$(ip r | grep -E "\/[0-9]+ dev eth0" | head -n 1 |cut -d' ' -f1)
# get 16 lower bits from IPv4 address
# TODO: should convert from hex, and also calculate how many bits dynamically
subnet_suffix=$(ip a show dev eth0 | grep -E 'inet ' | head -n 1 | cut -d' ' -f6 | cut -d'/' -f1 | cut -d. -f3- | tr -d . | xargs printf '%04d\n' | head -n 1)

# configure tunnel with kernel native translation/routing
ip tunnel add kubetunnel0 mode sit local $local_addr ttl 64
# we use ourselves as the relay. many online demos use ISP relays.
ip tunnel 6rd dev kubetunnel0 6rd-prefix "${rd_prefix_formatted}::/48" 6rd-relay_prefix "${local_subnet}"
# append this nodes 16 lower bits to the ULA prefix for this nodes unique IPv6 pod range
ip -6 addr add "${rd_prefix_formatted}:${subnet_suffix}::1/48" dev kubetunnel0
ip link set kubetunnel0 up
# delete the default address for the device with the node IP
ip -6 addr delete "::${local_addr}/96" dev kubetunnel0
# enable foo over UDP (makes ICMP6 and other goodness work in Azure)
ip link set name kubetunnel0 type sit encap fou encap-sport auto encap-dport 3544
ip addr show dev kubetunnel0

mkdir -p /etc/cni.d
tee /etc/cni.d/10-kubernetes-overlay.conflist >/dev/null <<EOF
	{
		"cniVersion": "0.3.1",
		"name": "kubenet",
		"type": "bridge",
		"bridge": "kubebridge0",
		"hairpinMode": true,
		"ipam": {
			"type": "host-local",
			"ranges": [
				[ { "subnet": "${rd_prefix_formatted}:${subnet_suffix}::1/48" } ],
			],
			"routes": [
				{ "dst": "0.0.0.0/0" },
				{ "dst": "${rd_prefix_formatted}:${subnet_suffix}::/48" }
			],
			"dataDir": "/var/run/cni/networks/kubernetes-overlay"
		}
	}
EOF