AINTEC 2019 Tutorial

10-my-cni-demo_node1.conf

{
    "cniVersion": "0.3.1",
    "name": "my-cni-demo",
    "type": "my-cni-demo",
    "podcidr": "10.42.0.0/24"
}

10-my-cni-demo_node2.conf

{
    "cniVersion": "0.3.1",
    "name": "my-cni-demo",
    "type": "my-cni-demo",
    "podcidr": "10.42.1.0/24"
}

demo.yaml

apiVersion: v1
kind: Pod
metadata:
  name: alpine1
spec:
  containers:
  - name: alpine
    image: alpine
    command:
      - "/bin/ash"
      - "-c"
      - "sleep 2000"
  nodeSelector:
    kubernetes.io/hostname: node1
---
apiVersion: v1
kind: Pod
metadata:
  name: nginx1
spec:
  containers:
  - name: nginx
    image: nginx
  nodeSelector:
    kubernetes.io/hostname: node1
---
apiVersion: v1
kind: Pod
metadata:
  name: nginx2
spec:
  containers:
  - name: nginx
    image: nginx
  nodeSelector:
    kubernetes.io/hostname: node2

k3s-node1

sudo k3s server \
 --no-deploy=coredns \
 --no-deploy=servicelb \
 --no-deploy=traefik \
 --no-flannel \
 --node-name=node1 \
 --node-ip=10.10.10.10 \
 --bind-address=10.10.10.10 \
 --advertise-address=10.10.10.10 \
 --cluster-secret=aintec2019 \
 -o /vagrant/kubeconfig.yaml

k3s-node2

sudo k3s agent \
 --no-flannel \
 --node-name=node2 \
 --node-ip=10.10.10.11 \
 --cluster-secret=aintec2019 \
 --server=https://10.10.10.10:6443

links

https://github.com/rancher/k3s/releases/download/v0.7.0/k3s
https://github.com/chanwit/k3s-cni-plugin/blob/master/loopback?raw=true

Kubectl for Linux
https://storage.googleapis.com/kubernetes-release/release/v1.14.4/bin/linux/amd64/kubectl

for Mac
https://storage.googleapis.com/kubernetes-release/release/v1.14.4/bin/darwin/amd64/kubectl

for Windows
https://storage.googleapis.com/kubernetes-release/release/v1.14.4/bin/windows/amd64/kubectl.exe

my-cni-demo

#!/bin/bash
log=/var/log/cni.log
config=`cat /dev/stdin`

echo >> $log
echo "COMMAND: $CNI_COMMAND" >> $log

case $CNI_COMMAND in
ADD)
    podcidr=$(echo $config | jq -r ".podcidr")
    podcidr_gw=$(echo $podcidr | sed "s:0/24:1:g")
    brctl addbr cni0
    ip link set cni0 up
    ip addr add "${podcidr_gw}/24" dev cni0

    # calculate $ip
    if [ -f /tmp/last_allocated_ip ]; then
        n=`cat /tmp/last_allocated_ip`
    else
        n=1
    fi
    n=$(($n+1))
    ip=$(echo $podcidr | sed "s:0/24:$n:g")
    echo $n > /tmp/last_allocated_ip

    host_ifname="veth$n"
    ip link add $CNI_IFNAME type veth peer name $host_ifname
    ip link set $host_ifname up

    mkdir -p /var/run/netns/
    ip link set $host_ifname master cni0
    ln -sfT $CNI_NETNS /var/run/netns/$CNI_CONTAINERID
    ip link set $CNI_IFNAME netns $CNI_CONTAINERID

    ip netns exec $CNI_CONTAINERID ip link set $CNI_IFNAME up
    ip netns exec $CNI_CONTAINERID ip addr add $ip/24 dev $CNI_IFNAME
    ip netns exec $CNI_CONTAINERID ip route add default via $podcidr_gw

    mac=$(ip netns exec $CNI_CONTAINERID ip link show $CNI_IFNAME | awk '/ether/ {print $2}')
    address="${ip}/24"
    output_template='
{
  "cniVersion": "0.3.1",
  "interfaces": [
      {
          "name": "%s",
          "mac": "%s",
          "sandbox": "%s"
      }
  ],
  "ips": [
      {
          "version": "4",
          "address": "%s",
          "gateway": "%s",
          "interface": 0
      }
  ]
}'

    output=$(printf "${output_template}" $CNI_IFNAME $mac $CNI_NETNS $address $podcidr_gw)
    echo $output >> $log
    echo "$output"

;;

DEL)
    rm -rf /var/run/netns/$CNI_CONTAINERID
;;

GET)
;;

VERSION)
echo '{
  "cniVersion": "0.3.1",
  "supportedVersions": [ "0.3.0", "0.3.1", "0.4.0" ]
}'
;;

*)
  echo "Unknown cni command: $CNI_COMMAND"
  exit 1
;;

esac

Vagrantfile

# -*- mode: ruby -*-
# vi: set ft=ruby :

Vagrant.configure("2") do |config|

  config.vm.box = "geerlingguy/ubuntu1604"

  config.vm.define "node1" do |box|
    box.vm.hostname = "node1"
    box.vm.network :private_network, ip: "10.10.10.10"

    box.vm.provision "shell", inline: <<-SHELL
      apt-get install -y bridge-utils jq

      cp /vagrant/k3s /usr/local/bin/k3s
      chmod +x /usr/local/bin/k3s

      mkdir -p /etc/cni/net.d
      cp /vagrant/10-my-cni-demo_node1.conf /etc/cni/net.d/10-my-cni-demo.conf

      mkdir -p /opt/cni/bin
      cp /vagrant/loopback /opt/cni/bin/loopback
      cp /vagrant/my-cni-demo /opt/cni/bin/my-cni-demo
      chmod +x /opt/cni/bin/loopback
      chmod +x /opt/cni/bin/my-cni-demo
    SHELL

  end

  config.vm.define "node2" do |box|
    box.vm.hostname = "node2"
    box.vm.network :private_network, ip: "10.10.10.11"

    box.vm.provision "shell", inline: <<-SHELL
      apt-get install -y bridge-utils jq

      cp /vagrant/k3s /usr/local/bin/k3s
      chmod +x /usr/local/bin/k3s

      mkdir -p /etc/cni/net.d
      cp /vagrant/10-my-cni-demo_node2.conf /etc/cni/net.d/10-my-cni-demo.conf

      mkdir -p /opt/cni/bin
      cp /vagrant/loopback /opt/cni/bin/loopback
      cp /vagrant/my-cni-demo /opt/cni/bin/my-cni-demo
      chmod +x /opt/cni/bin/loopback
      chmod +x /opt/cni/bin/my-cni-demo
    SHELL

  end

  config.vm.provider "virtualbox" do |vb|
    vb.memory = "1024"
  end

end