Kubernetes at Home on Raspberry Pi 4, Part 2

Continue from part 1

It’s recommended to change all Pi’s password also run ssh-copy-id [email protected] to enable SSH public key login.

There are lots of steps to prepare before kubeadm is installed, so I made this ansible repository to simplify this repeating process. Please see here. The ansible role will do the following tasks:

  • set host name, update /etc/hosts file
  • enable network bridge
  • disable swap, kubeadm doesn’t like it!
  • set timezone. You may want to change it to yours
  • install docker community edition
  • install kubeadm
  • use iptables-legacy (Reference here)

Once the ansible playbook finishes successfully, kubeadm is ready for some action to set up the kubernetes master node, aka. control plane

# the following command is to be run in the master node
# I prefer to use flannelas the CNI(container network interface) because it's lightweight comparing to others like weave.net. So the CIDR is to be set as follow
$ sudo kubeadm init --pod-network-cidr 10.244.0.0/16

Then as the kubeadm finishes it will give some instructions to continue. First thing is to copy the admin.conf so kubectl command can authenticate with the control plane. Also save the kubeadm join 192.168.1.80:6443 --token xxx --discovery-token-ca-cert-hash sha256:xxx instruction as it will be needed later

$ sudo cp -i /etc/kubernetes/admin.conf ~/.kube/config
$ kubectl get node
...
$ kubectl get pods
...

The coredns pods will be at pending state, this is expected. After the CNI is installed this will be fixed automatically. Next step is to install a CNI, in my case it’s flannel.

$ kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/62e44c867a2846fefb68bd5f178daf4da3095ccb/Documentation/kube-flannel.yml

In a few minutes the flannel and coredns pods should be in available state. The run the join command saved earlier on other Pi nodes

kubeadm join 192.168.1.80:6443 --token xxx     --discovery-token-ca-cert-hash sha256:xxx

And back to the master node, you should be able to see the new work node in the output

$ kubectl get nodes

TBC

Kubernetes at Home on Raspberry Pi 4, Part 1

3 x Raspberry Pi 4

I mostly followed/was inspired by this tutorial but with some tweak/fix to recent(Sep 2019) software versions. Also this is a pure Linux walk-through as I don’t use a Mac.

I planned to build a home Kubernetes(k8s) cluster and migrate home servers including the one this blog is running on to the k8s cluster, for a long time. But the Raspberry Pi 2 has 1GB of memory and is not quite appealing for any practical purpose. (I know, I know, we used to run a computer with mega bytes of memory…) When Raspberry Pi 4 with 4GB of memory is available, I believed I need to wait no more.

The 3 Pi 4s I got are from eBay, surprisingly this time the offer in eBay was better than Amazon! I didn’t think I need the cases for the Pis, because I heard the Pi 4 is more powerful and can get hot comparing to previous ones.

I chose Raspbian for now, as it supports all devices in the Pi 4. Ubuntu Server could be a better choice but it only support up to Pi 3. And as a command line veteran I use this line to flash the MicroSD cards:

# if you copy and paste you may need to verify the file name and the card reader device in your computer, ie. I'm not responsible for anything 🙂
$ unzip -p 2019-07-10-raspbian-buster-lite.zip |sudo dd bs=4M of=/dev/mmcblk0

To enable SSH access at first boot, create an empty file called ssh in /boot partition:

# once again, this path could be different on your system.
$ sudo touch /run/media/raynix/boot/ssh

After this, use the sync command to make sure everything has been written to the card. Then you can pull the MicroSD card out of your card reader slot and put it into the Pi 4.

Something required before powering up the Pi 4:

  • Pi 4 connected to the router/switch with Ethernet cable
  • 5V power supply with USB-C connector
  • DHCP enabled in LAN

After the Pi 4 is powered up, the green LED should flash a bit before you can see raspberrypi.localdomain online( the localdomain part is usually the default for some routers, but can be something else depending on your router setup). Then you should be able to:

# default user is pi, and password is raspberry
$ ssh [email protected]
$ cat <<EOF |sudo tee -a /etc/dhcpcd.conf
interface eth0
static ip_address=192.168.1.200/24
static routers=192.168.1.1
static domain_name_servers=192.168.1.1
EOF

This will set the Pi 4 to a static IP address after reboot. Repeat this step for each Pi 4 but obviously they should have different IPs, eg. master has 192.168.1.200 and node1 has 192.168.1.201, etc.

TBC.

Run Fedora 29 on Dell XPS 15 9570

Here’s a list of things to do to get Fedora 29 running optimally on Dell XPS 15 9570:

First, disable Secure Boot with the stock Windows 10 and in BIOS otherwise Fedora installer on a USB stick won’t boot. I still don’t really see the necessity to have this Secure Boot, except to buy more time for Windows obviously.

Then I need to set SATA mode from RAID to AHCI in BIOS, or the Linux installer can’t find the drive. The SATA mode was set to RAID ON, which probably makes more sense if there’s 1 more drive in the laptop.

Hit F12 to choose boot device and install Fedora 29 using a USB drive, then the laptop will be booted into Fedora Live.

There were some warnings regarding nouveau drive so I had to disable nouveau and turn off nvidia device at start. The way bbswitch is installed has changed a bit so I installed it following this. After the nvidia device disabled at boot, the laptop is much much quieter.

According to Arch Linux Wiki, the laptop uses S2 suspend instead of S3. This can be fixed by added mem_sleep_default=deep to kernel parameters and then

grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg

and reboot. The result can be verified by

$ cat /sys/power/mem_sleep
s2idle [deep]

I’ll see how long the battery can hold up. 🙂

关闭 Dell XPS 15 9550 的独立显卡

最近我从 ebay 淘了个二手 Dell XPS 15 笔记本电脑, 2016年的而且配置很高, 但价格相当便宜. 既然好货不便宜, 这电脑是不是有问题? 是的, 卖家承认电脑的 nVidia 独立显卡有故障, 装好驱动程序之后 Windows 就会僵死, 但禁用了它之后一切正常, 当然就不要指望能玩什么像样的游戏了. 不过正好我也不打算在笔记本电脑上玩游戏的, 而且 Dell 对 Linux 的支持算是很好的, 于是我欣然买下.

电脑到手后我装了 Fedora 25, 一切顺利, 送走了 Windows 10. 顺便提及, Fedora 25 已经能检测到 XPS 15 BIOS 有更新可以安装了, 很赞.

启用 nVidia 驱动后果然死锁. 索性把 nVidia 关闭了吧, 还能延长电池的使用时间呢. 首先添加 bumblebee, 参考(在 Fedora 25 上测试通过, 其他 Linux 可能需要不同的设置):

https://fedoraproject.org/wiki/Bumblebee#Installation

安装 bbswitch:

sudo -i
VER=$(uname -r)
dnf install kernel-devel-$VER kernel-headers-$VER bbswitch-dkms

禁止系统自动装载 nVidia 的开源驱动 nouveau:

echo "blacklist nouveau" > /etc/modprobe.d/nouveau.conf

让 bbswitch 自动装载, 并在装载时关闭独立显卡:

echo "bbswitch" > /etc/modules-load.d/bbswitch.conf
echo "options bbswitch load_state=0" > /etc/modprobe.d/bbswitch.conf

重新启动系统之后, 测试一下:

cat /proc/acpi/bbswitch
0000:01:00.0 OFF

OFF 就说明成功了 🙂