persica cluster
This is a cluster of three identical nodes, named persica1/2/3
- Alma Linux 9.1 x64
- Dell Optiplex 9020 Micro
- Intel Core i5-4590T @ 2.00 GHz
- 16gb DDR3-1600
- 128gb SSD
Contents
k8s notes
- Make a simple 3-node cluster
- Single-node control plane will run externally, on illustrious
Use kubeadm to build the cluster: https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/
- Selected containerd as the container runtime
- Will use Flannel as the networking plugin
- Allocated IPs:
- persica1 / 192.168.1.31
- persica2 / 192.168.1.32
- persica3 / 192.168.1.33
- Ingress: undecided so far
- Cgroup driver: let's use systemd
- k8s version: whatever is latest right now (2023-04-04)
Build notes
Per node
Update the BIOS using this guide: https://www.dell.com/support/kbdoc/en-au/000131486/update-the-dell-bios-in-a-linux-or-ubuntu-environment#updatebios2015
Despite the usual Dell docs saying you need to make a DOS boot disk and run the flash updater app from there, it turns out that the BIOS Flash Update target (mash F12 to get the one-time boot menu) can read the 9020MA19.exe file from a FAT32 filesystem on a USB stick just fine
Not sure if this only works in UEFI mode or not, but I kinda don't care because we want to be in UEFI mode
- This applies to systems made from 2015 or later
- The latest BIOS update for the Optiplex 9020M is version A19, released
- Set BIOS to full UEFI mode, no legacy
- We'll be using DHCP, so find the MAC address so we can give it a consistent IP address when it boots
- Add the MAC address and IP assignment to dnsmasq on calico (a pihole box)
/etc/dnsmasq.d/02-pihole-dhcp-persica-cluster.conf
Something like this
dhcp-host=98:90:96:BE:89:52,set:persica,192.168.1.31,persica1,5m # one dhcp-host line per host dhcp-boot=tag:persica,grub/grubx64.efi,illustrious.thighhighs.top,192.168.1.12
Run pihole restartdns after making changes
- PXE boot for kickstart install, which will hit calico for DHCP, then illustrious for the boot image and kickstart config
- tftpd-hpa is running on illustrious
Upstream repo mirror: https://repo.almalinux.org/almalinux/9/BaseOS/x86_64/os/EFI/BOOT/
Drop that content in /srv/tftp/
root@illustrious:/srv/tftp# tree . ├── BOOTX64.EFI ├── default.efi ├── grub │ ├── grub.cfg │ ├── grub.cfg-01-98-90-96-be-89-52 │ └── grubx64.efi ├── images │ └── Alma-9.1 │ ├── initrd.img │ └── vmlinuz ├── ipxe.efi └── shimx64.efi
Add a grub config fragment for the host's MAC address: grub.cfg-01-xx-xx-xx-xx-xx-xx
- Make sure the grub config has the correct URL for its kickstart config
kickstart file served from /data/www/illustrious/ks: https://illustrious.thighhighs.top/ks/persica1.ks.cfg
- Make sure your per-host config file has the correct name
- KS references:
Generator tool: https://access.redhat.com/labs/kickstartconfig/
- k8s doesn't play well with swap so we need to disable it. Provision a minimal swap volume of 1gb, then disable it later
This was useful for figuring out the TFTP stuff for the first time: https://askubuntu.com/questions/1183487/grub2-efi-boot-via-pxe-load-config-file-automatically
Paths are hardcoded into the grubx64.efi binary, meaning HDD and PXE versions aren't the same. Make sure you put all the grub stuff in a grub/ directory. Check the $prefix to see where it's searching:
UEFI settings
Get to the UEFI
- Probably get stuck in windows for first boot
- Win, then "UEFI", get to advanced startup options
- Boot with Advanced Boot Options
- Troubleshoot, Advanced Options, UEFI Firmware Settings, Restart
Record details
- Get the LOM MAC Address from Settings, General, System Info
Change settings
- General
- Boot Sequence
- Select UEFI boot list
- Advanced Boot Options
- Disable Legacy OPROMs
- UEFI Boot Path Security
- Set to Never
- Date/Time
- Set clock to approx correct for UTC time
- Boot Sequence
- System Configuration
- Integrated NIC
- Enable UEFI Network Stack
- Enabled w/ PXE
- SATA Operation
- AHCI
- SMART Reporting
- Disabled, we don't need it
- Audio
- Disable all audio, we don't need it
- Integrated NIC
- Security
- TPM Security
- Check everything except Clear
- Activated
- CPU XD support
- Enabled
- TPM Security
- Secure Boot
- Secure Boot Enable
- Disabled
- Secure Boot Enable
- Performance
- Multi-core support: All
- Speedstep: Enabled
- C-states: Enabled
- Limit CPUID: Disabled
- Turboboost: Enabled
- Power Management
- AC Recovery: Power On
- Deep Sleep Control: Disabled
- USB Wake Support: Enable USB wake from Standby
- Wake on LAN/WLAN: LAN with PXE Boot
- Block Sleep: Enable blocking of sleep
- POST Behaviour
- Keyboard Errors: Disable error detection
- Virtualisation support
- Enable VT
- Enable VT-d
- Enable Trusted Execution
Reboot and go back in again.
- Boot only from IPv4 with NIC (PXE boot)
Ansible management after kickstart build
This is getting everything to the state where I can bootstrap the cluster. I should ansible'ise everything, making minimal assumptions about the kickstart part of the process.
I'm keeping a simple ansible repo in ~/git/persica-ansible/
I have a basic set of roles to get the nodes into a workable state, right before I invoke kubeadm for the first time.
---
- name: Configure persica k8s cluster
hosts: persica
roles:
- role: common
tags: common
- role: docker_for_kube
tags: docker_for_kube
- role: kube_daemons
tags: kube_daemons
Initialise the control plane
This is manual of course, no ansible here.
This will be a single-node control plane, but we should specify --control-plane-endpoint anyway. persica1 is going to be our control plane.
Our Pod network add-on will be Flannel. We can specify --pod-network-cidr but I'll try without first.
- It'll detect containerd
The default --apiserver-advertise-address will be fine, let it autodetect
I added a custom CNAME record to local pihole (calico) and Gandi (public service), for persica-endpoint => persica1. Unlike the DHCP stuff, this is in the general DNS web interface, not a custom config file.
After a bunch of faffing around to fix up the firewall config, bridge filtering kernel module, and enabling ipv4 forwarding, the init begins after passing preflight checks.
[root@persica1 ~]# kubeadm init --control-plane-endpoint=persica-endpoint
[init] Using Kubernetes version: v1.27.1
[preflight] Running pre-flight checks
[WARNING Firewalld]: firewalld is active, please ensure ports [6443 10250] are open or your cluster may not function correctly
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
W0415 03:43:19.958609 39430 images.go:80] could not find officially supported version of etcd for Kubernetes v1.27.1, falling back to the nearest etcd version (3.5.7-0)
W0415 03:43:52.646765 39430 checks.go:835] detected that the sandbox image "registry.k8s.io/pause:3.6" of the container runtime is inconsistent with that used by kubeadm. It is recommended that using "registry.k8s.io/pause:3.9" as the CRI sandbox image.
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local persica-endpoint persica1] and IPs [10.96.0.1 192.168.1.31]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [localhost persica1] and IPs [192.168.1.31 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [localhost persica1] and IPs [192.168.1.31 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Starting the kubelet
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
W0415 03:44:21.781505 39430 images.go:80] could not find officially supported version of etcd for Kubernetes v1.27.1, falling back to the nearest etcd version (3.5.7-0)
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[kubelet-check] Initial timeout of 40s passed.
Unfortunately, an error has occurred:
timed out waiting for the condition
This error is likely caused by:
- The kubelet is not running
- The kubelet is unhealthy due to a misconfiguration of the node in some way (required cgroups disabled)
If you are on a systemd-powered system, you can try to troubleshoot the error with the following commands:
- 'systemctl status kubelet'
- 'journalctl -xeu kubelet'
Additionally, a control plane component may have crashed or exited when started by the container runtime.
To troubleshoot, list all containers using your preferred container runtimes CLI.
Here is one example how you may list all running Kubernetes containers by using crictl:
- 'crictl --runtime-endpoint unix:///var/run/containerd/containerd.sock ps -a | grep kube | grep -v pause'
Once you have found the failing container, you can inspect its logs with:
- 'crictl --runtime-endpoint unix:///var/run/containerd/containerd.sock logs CONTAINERID'
error execution phase wait-control-plane: couldn't initialize a Kubernetes cluster
To see the stack trace of this error execute with --v=5 or higherNo worky :/
Maybe I need the control plane on a separate node after all. I'll try illustrious.
- copy containerd/config.toml to illustrious
- apt install -y apt-transport-https ca-certificates curl
curl -fsSLo /etc/apt/trusted.gpg.d/kubernetes-archive-keyring.gpg https://packages.cloud.google.com/apt/doc/apt-key.gpg
prep repo defn
cat <<EOF > /etc/apt/sources.list.d/kubernetes.sources X-Repolib-Name: Kubernetes Enabled: yes Types: deb URIs: https://apt.kubernetes.io/ Suites: kubernetes-xenial Architectures: amd64 Components: main Signed-By: /etc/apt/trusted.gpg.d/kubernetes-archive-keyring.gpg X-Repolib-ID: Kubernetes EOF
- apt update
- apt install -y kubelet kubeadm kubectl
- apt-mark hold kubelet kubeadm kubectl
Now try kubeadm again.
Oh sonovabitch! Config not well described: https://github.com/containerd/containerd/issues/6964
Fixed config /etc/containerd/config.toml:
version = 2
disabled_plugins = []
[plugins."io.containerd.grpc.v1.cri".containerd.runtimes]
[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc]
base_runtime_spec = ""
cni_conf_dir = ""
cni_max_conf_num = 0
container_annotations = []
pod_annotations = []
privileged_without_host_devices = false
runtime_engine = ""
runtime_path = ""
runtime_root = ""
runtime_type = "io.containerd.runc.v2"
[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]
BinaryName = ""
CriuImagePath = ""
CriuPath = ""
CriuWorkPath = ""
IoGid = 0
IoUid = 0
NoNewKeyring = false
NoPivotRoot = false
Root = ""
ShimCgroup = ""
SystemdCgroup = true
# They suggest pinning this image, so we'll do that. This is the out-of-box default.
# https://kubernetes.io/docs/setup/production-environment/container-runtimes/#override-pause-image-containerd
[plugins."io.containerd.grpc.v1.cri"]
sandbox_image = "registry.k8s.io/pause:3.9"We could/should be using kubeadm init with a configuration file: https://kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file/
Apr 15 04:48:26 illustrious.thighhighs.top systemd[1]: Started kubelet: The Kubernetes Node Agent. Apr 15 04:48:26 illustrious.thighhighs.top kubelet[12354]: Flag --container-runtime-endpoint has been deprecated, This parameter should be set via the config file specified by the Kubelet's --config flag. See https://kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file/ for more information. Apr 15 04:48:26 illustrious.thighhighs.top kubelet[12354]: Flag --pod-infra-container-image has been deprecated, will be removed in a future release. Image garbage collector will get sandbox image information from CRI.
But screw that. Because guess what, it's also poorly documented!
Initialising the control plane now actually works
kubeadm init --control-plane-endpoint=persica-endpoint Setup my `~/.kube/` config stuff as directed. Apparently this is an uber-superuser, so I shouldn't be using it regularly. Oh. cat <<EOF > kubeconfig_example.yml apiVersion: kubeadm.k8s.io/v1beta3 kind: ClusterConfiguration # Will be used as the target "cluster" in the kubeconfig clusterName: "persica" # Will be used as the "server" (IP or DNS name) of this cluster in the kubeconfig controlPlaneEndpoint: "persica-endpoint.thighhighs.top:6443" # The cluster CA key and certificate will be loaded from this local directory certificatesDir: "/etc/kubernetes/pki" EOF # on illustrious kubeadm kubeconfig user --config kubeconfig_example.yml --client-name furinkan --validity-period 8760h
Now try adding a pod network. We'll use Flannel, and find the docs ourselves: https://github.com/flannel-io/flannel#deploying-flannel-manually
# from suomi kubectl --context=persica-admin apply -f https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml kubectl --context=persica-admin get pods --all-namespaces NAMESPACE NAME READY STATUS RESTARTS AGE kube-flannel kube-flannel-ds-zr6fb 0/1 CrashLoopBackOff 1 (16s ago) 34s kube-system coredns-5d78c9869d-mp7p9 0/1 ContainerCreating 0 66m kube-system coredns-5d78c9869d-tlsc6 0/1 ContainerCreating 0 66m kube-system etcd-illustrious.thighhighs.top 1/1 Running 1 66m kube-system kube-apiserver-illustrious.thighhighs.top 1/1 Running 1 66m kube-system kube-controller-manager-illustrious.thighhighs.top 1/1 Running 1 66m kube-system kube-proxy-5mntm 1/1 Running 0 66m kube-system kube-scheduler-illustrious.thighhighs.top 1/1 Running 1 66m
Doesn't work because we don't have the same podCIDR, and the default isn't compatible with whatever kubeadm does? FFS!
https://devops.stackexchange.com/questions/5898/how-to-get-kubernetes-pod-network-cidr
Okay so I can either nuke the cluster and reinstantiate it with podCIDR, or just reinstall the network plugin or something. Let's try the latter.
get the current podCIDR: https://devops.stackexchange.com/a/14867
- kubeadm config print init-defaults | grep serviceSubnet
wget https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml
- Edit it
- Reapply it? kubectl apply -f kube-flannel.yml
- Is it still crashlooping? kubectl get pods --all-namespaces
Yeah.
Fukkit try again
# on illustrious kubeadm reset rm -rf /etc/cni/net.d/ rm -rf ~/.kube/ # fix the init: https://github.com/flannel-io/flannel/issues/728#issuecomment-308878912 kubeadm init --control-plane-endpoint=persica-endpoint.thighhighs.top --pod-network-cidr=10.244.0.0/16 # Fix up my kubectl creds again # install flannel again kubectl apply -f https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml # is it working now? kubectl get pods --all-namespaces # IT FUCKING WORKS!!
Now we join some worker nodes to the cluster, finally.
# on persica1
kubeadm join persica-endpoint.thighhighs.top:6443 --token FOO.FOOFOOFOO \
--discovery-token-ca-cert-hash sha256:BARBARBARBARBARBARBARBARBARBARBARBARBARBARBARBARBARBARBARBARBAR
[preflight] Running pre-flight checks
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Starting the kubelet
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...
This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.
Run 'kubectl get nodes' on the control-plane to see this node join the cluster.It's joined but apparently NotReady:
root@illustrious:~# kubectl get nodes NAME STATUS ROLES AGE VERSION illustrious.thighhighs.top NotReady control-plane 17m v1.27.1 persica1 NotReady <none> 2m7s v1.27.0
Apparently coredns won't start because of taints, as described here:
https://serverfault.com/questions/1064936/coredns-pods-stuck-in-pending-state
- No explanation as to why the taints aren't going away
- Similar problem here
- Someone says to just restart containerd
Fuck yoooooouuu, now the coredns containers are running. I probably shouldn't have jumped the gun and joined all the worker nodes... I need to kick them so they start properly.
root@illustrious:~# kubectl get pods --all-namespaces NAMESPACE NAME READY STATUS RESTARTS AGE kube-flannel kube-flannel-ds-4p4wd 0/1 Init:0/2 0 21m kube-flannel kube-flannel-ds-6qfrm 0/1 Init:0/2 0 12m kube-flannel kube-flannel-ds-kb94w 0/1 Init:0/2 0 12m kube-flannel kube-flannel-ds-vctrt 1/1 Running 0 30m kube-system coredns-5d78c9869d-dqnkh 1/1 Running 0 36m kube-system coredns-5d78c9869d-rbmhm 1/1 Running 0 36m kube-system etcd-illustrious.thighhighs.top 1/1 Running 2 36m kube-system kube-apiserver-illustrious.thighhighs.top 1/1 Running 2 36m kube-system kube-controller-manager-illustrious.thighhighs.top 1/1 Running 0 36m kube-system kube-proxy-8dl56 0/1 ContainerCreating 0 12m kube-system kube-proxy-dppxt 0/1 ContainerCreating 0 21m kube-system kube-proxy-ljk6c 1/1 Running 0 36m kube-system kube-proxy-t7gcn 0/1 ContainerCreating 0 12m kube-system kube-scheduler-illustrious.thighhighs.top 1/1 Running 2 36m
Try deleting and re-adding a node. From https://stackoverflow.com/a/54220808/806927
# on illustrious kubectl get nodes kubectl drain persica1 kubectl drain persica1 --ignore-daemonsets --delete-local-data kubectl delete node persica1 # on persica1 kubeadm reset then join again
Looks like the kube-proxy is having trouble starting on persica1. And while it's only a warning, I bet it's more significant than that.
root@illustrious:~# kubectl get pods --all-namespaces NAMESPACE NAME READY STATUS RESTARTS AGE kube-flannel kube-flannel-ds-gjq5h 0/1 Init:0/2 0 3m33s kube-flannel kube-flannel-ds-vctrt 1/1 Running 0 41m kube-system coredns-5d78c9869d-dqnkh 1/1 Running 0 47m kube-system coredns-5d78c9869d-rbmhm 1/1 Running 0 47m kube-system etcd-illustrious.thighhighs.top 1/1 Running 2 47m kube-system kube-apiserver-illustrious.thighhighs.top 1/1 Running 2 47m kube-system kube-controller-manager-illustrious.thighhighs.top 1/1 Running 0 47m kube-system kube-proxy-ljk6c 1/1 Running 0 47m kube-system kube-proxy-xpv58 0/1 ContainerCreating 0 3m33s kube-system kube-scheduler-illustrious.thighhighs.top 1/1 Running 2 47m root@illustrious:~# kubectl get events --namespace=kube-system | grep pod/kube-proxy-xpv58 4m29s Normal Scheduled pod/kube-proxy-xpv58 Successfully assigned kube-system/kube-proxy-xpv58 to persica1 9s Warning FailedCreatePodSandBox pod/kube-proxy-xpv58 Failed to create pod sandbox: open /run/systemd/resolve/resolv.conf: no such file or directory # on persica1 mkdir /run/systemd/resolve ln -s /etc/resolv.conf /run/systemd/resolve/resolv.conf wtf now there's another error: root@illustrious:~# kubectl get events --namespace=kube-system | grep pod/kube-proxy-grqhf 20s Normal Scheduled pod/kube-proxy-grqhf Successfully assigned kube-system/kube-proxy-grqhf to persica1 6s Warning FailedCreatePodSandBox pod/kube-proxy-grqhf Failed to create pod sandbox: rpc error: code = InvalidArgument desc = failed to create containerd container: create container failed validation: container.Runtime.Name must be set: invalid argument
I think I haven't deployed a good containerd config everywhere yet. Deployed that, and suddenly the damn kube-proxy and kube-flannel containers are working.
Now I can add the other two nodes, still need to fix the resolv.conf manually.
root@illustrious:~# kubectl get nodes -o wide NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME illustrious.thighhighs.top Ready control-plane 78m v1.27.1 192.168.1.12 <none> Ubuntu 22.04.2 LTS 5.15.0-69-generic containerd://1.6.20 persica1 Ready <none> 21m v1.27.0 192.168.1.31 <none> AlmaLinux 9.1 (Lime Lynx) 5.14.0-162.6.1.el9_1.x86_64 containerd://1.6.20 persica2 Ready <none> 2m41s v1.27.0 192.168.1.32 <none> AlmaLinux 9.1 (Lime Lynx) 5.14.0-162.6.1.el9_1.x86_64 containerd://1.6.20 persica3 Ready <none> 33s v1.27.0 192.168.1.33 <none> AlmaLinux 9.1 (Lime Lynx) 5.14.0-162.6.1.el9_1.x86_64 containerd://1.6.20
Good enough for now!
Making ingress work
I don't understand this well enough, but I want to use ingress-nginx. Here's a page about it, albeit not using raw kubectl: https://kubernetes.github.io/ingress-nginx/kubectl-plugin/
Maybe this one too: https://medium.com/tektutor/using-nginx-ingress-controller-in-kubernetes-bare-metal-setup-890eb4e7772
Making load balancing work
I thought I wouldn't need it, but it looks like I do, if I want sensible useful functionality. Here's an explanation of why I want to use Metal LB, and it's not just for BGP-based configs: https://github.com/kubernetes/ingress-nginx/blob/main/docs/deploy/baremetal.md
I'll use it in L2 mode with ARP/NDP I think. Just need to dedicate a bunch of IPs to it so it can manage the traffic to them.