Instructions to hack up WSL2 on Windows 10 Build 18917 to run k3s (Kubernetes) and rio

# Install WSL2
https://docs.microsoft.com/en-us/windows/wsl/wsl2-install

I already had Ubuntu-18.04 installed in wsl 1.  So I just did `wsl --set-version Ubuntu-18.04 2`

# Compile Kernel
Using Ubuntu 18.04 (I'm sure any distro will work), inside WSL2 download https://thirdpartysource.microsoft.com/download/Windows%20Subsystem%20for%20Linux%20v2/May%202019/WSLv2-Linux-Kernel-master.zip
and extract to a folder.  The latest version of the kernel source is available at (https://github.com/microsoft/WSL2-Linux-Kernel)

In the extracted kernel source run

```bash
# Install basically "compile kernel" crap
sudo apt install build-essential flex bison libssl-dev libelf-dev

# Setup kernel config
cp Microsoft/config-wsl .config
cat >> .config << EOF
CONFIG_BRIDGE_NETFILTER=y
CONFIG_NETFILTER_XT_MATCH_COMMENT=y
CONFIG_NETFILTER_XT_MATCH_MULTIPORT=y
CONFIG_NETFILTER_XT_MATCH_OWNER=y
CONFIG_NETFILTER_XT_MATCH_PHYSDEV=y
CONFIG_VXLAN=y
CONFIG_GENEVE=y
EOF
make oldconfig

# Compile and drink beverage of choice
make -j $(nproc)
```

# Update WSL kernel

1. Copy `arch/x86/boot/bzImage` to somewhere outside WSL2 (`/mnt/c/Users/${USER}/Desktop`)
2. Shutdown WSL2 `wsl --shutdown`
3. Copy bzImage to `c:\Windows\System32\lxss\tools\kernel`.  Make sure you backup the existing `kernel` file (although the original is still in another location).  I had to copy through explorer.exe because of permissions issues.

# Install K3s

You can't install k3s using the curl script because there is no supervisor (systemd or openrc) in WSL2.

1. Download k3s binary from https://github.com/rancher/k3s/releases/latest
2. `chmod +x k3s`
3. Run k3s `sudo ./k3s server`

# Setup access
1. Copy `/etc/rancher/k3s/k3s.yaml` from WSL to your home in Windows to %HOME%\.kube\config.  Edit the copied file and change the
   server URL from `https://localhost:6443` to the IP of the your WSL2 instance (`ip addr show dev eth0`).  So something like `https://192.168.170.170:6443`.
2. Run kubectl from windows (got to download kubectl.exe from somewhere)

# Bonus Install Rio
1. Download rio-windows-amd64 from https://github.com/rancher/rio/releases/tag/v0.2.0-rc1 to rio.exe
2. Run `./rio install`
3. Start doing stuff with rio :)