There’s a ton of the tutorials on how to get Kubernetes installed onto your Raspberry Pi, so… let’s write another one. 😊
As mentioned in my last post, I’ve found my forgotten Raspberry Pi, and played around with installing and configuring Raspbian Buster on it.
Today, I wanted to check if it will be possible to install Kubernetes onto such small machine – they are many articles on the “widest of the world’s webs” that say “Yes, it can be done!“, so I’ve decided to give it a try! And I chose to follow one of them (seemed like a nice reference).
As you remember, I’m starting with a cleanly installed (and just slightly customized) Raspbian Buster and building it from there.
And I’ll be using kubeadm for installing my cluster.
So, once I had at least two machines (my Raspberry Pi for the “control plane” and Ubuntu 20.04 LTS Hyper-V virtual machine as the “node” – you can read more about it here), I prepared them like this:
- install Docker (in my case)
- change the default cgroups driver for Docker to systemd
- add cgroups limit support (for my Raspberry Pi 3)
- configure iptables
- disable swap (this one was a bit challenging)
- prepare for Kubernetes installation (source, keys, kubeadm)
- install Kubernetes “control plane”
- add flannel
- add a node to the cluster
- test with some workload
One thing that bothered me (on Buster) was disabling swap in a way that it also stays disabled after a reboot (I know, it’s the details that eventually get you) – after a while, I’ve stumbled on this forum post and the solution provided by “powerpete” did the trick! Thank you, @powerpete! 😊
And finally, details about the each step are here (outputs are commented and somewhat redacted/condensed):
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# install Docker sudo apt install -yqq docker.io # The following additional packages will be installed: # cgroupfs-mount git git-man libcurl3-gnutls liberror-perl libintl-perl libintl-xs-perl libltdl7 libmodule-find-perl # libmodule-scandeps-perl libnspr4 libnss3 libproc-processtable-perl libsort-naturally-perl libterm-readkey-perl # needrestart runc tini # ... # The following NEW packages will be installed: # cgroupfs-mount docker.io git git-man libcurl3-gnutls liberror-perl libintl-perl libintl-xs-perl libltdl7 # libmodule-find-perl libmodule-scandeps-perl libnspr4 libnss3 libproc-processtable-perl libsort-naturally-perl # libterm-readkey-perl needrestart runc tini # 0 upgraded, 19 newly installed, 0 to remove and 0 not upgraded. # ... # check docker info and change the default cgroups driver for Docker to systemd sudo docker info # ... # Server Version: 18.09.1 # Storage Driver: overlay2 # ... # Logging Driver: json-file # Cgroup Driver: cgroupfs # ... # Kernel Version: 5.4.79-v7+ # Operating System: Raspbian GNU/Linux 10 (buster) # OSType: linux # Architecture: armv7l # CPUs: 4 # Total Memory: 974.4MiB # Name: pimaster # ... # # WARNING: No memory limit support # WARNING: No swap limit support # WARNING: No kernel memory limit support # WARNING: No oom kill disable support # create/edit the /etc/docker/daemon.json file (with the following content, uncommented) and restart docker service sudo nano /etc/docker/daemon.json # { # "exec-opts": ["native.cgroupdriver=systemd"], # "log-driver": "json-file", # "log-opts": { # "max-size": "100m" # }, # "storage-driver": "overlay2" # } sudo systemctl restart docker # docker info now showing the changed cgroup driver sudo docker info # ... # Cgroup Driver: systemd # ... # # WARNING: No memory limit support # WARNING: No swap limit support # WARNING: No kernel memory limit support # WARNING: No oom kill disable support # add cgroups limit support and reboot sudo sed -i '$ s/$/ cgroup_enable=cpuset cgroup_enable=memory cgroup_memory=1 swapaccount=1/' /boot/cmdline.txt # console=tty1 root=PARTUUID=03f5b65e-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait cgroup_enable=cpuset cgroup_enable=memory cgroup_memory=1 swapaccount=1 sudo reboot # recheck docker info (warnings should be gone) sudo docker info # ... # Storage Driver: overlay2 # ... # Logging Driver: json-file # Cgroup Driver: systemd # ... # Operating System: Raspbian GNU/Linux 10 (buster) # ... # configure iptables cat << EOF | sudo tee /etc/sysctl.d/k8s.conf net.bridge.bridge-nf-call-ip6tables = 1 net.bridge.bridge-nf-call-iptables = 1 EOF # configure iptables (add lines to the file, uncommented) and apply the configuration sudo nano /etc/sysctl.d/k8s.conf # net.bridge.bridge-nf-call-ip6tables = 1 # net.bridge.bridge-nf-call-iptables = 1 sudo sysctl --system * Applying /etc/sysctl.d/98-rpi.conf ... # kernel.printk = 3 4 1 3 # vm.min_free_kbytes = 16384 # * Applying /etc/sysctl.d/99-sysctl.conf ... # * Applying /etc/sysctl.d/k8s.conf ... # net.bridge.bridge-nf-call-ip6tables = 1 # net.bridge.bridge-nf-call-iptables = 1 # * Applying /etc/sysctl.d/protect-links.conf ... # fs.protected_hardlinks = 1 # fs.protected_symlinks = 1 # * Applying /etc/sysctl.conf ... # disable swap # check current swap utilization/settings free -m # total used free shared buff/cache available # Mem: 974 82 709 6 182 834 # Swap: 99 0 99 sudo cat /etc/fstab # proc /proc proc defaults 0 0 # PARTUUID=03f5b65e-01 /boot vfat defaults 0 2 # PARTUUID=03f5b65e-02 / ext4 defaults,noatime 0 1 # disable swap (note - disabling the service as well!) sudo dphys-swapfile swapoff sudo dphys-swapfile uninstall sudo update-rc.d dphys-swapfile remove sudo systemctl disable dphys-swapfile.service # Synchronizing state of dphys-swapfile.service with SysV service script with /lib/systemd/systemd-sysv-install. # Executing: /lib/systemd/systemd-sysv-install disable dphys-swapfile # Removed /etc/systemd/system/multi-user.target.wants/dphys-swapfile.service. # optionally - reboot & recheck free -m # total used free shared buff/cache available # Mem: 974 79 745 12 149 832 # Swap: 0 0 0 # prepare for Kubernetes installation (source, keys, kubeadm) and "lock" the kubelet, kubeadm and kubectl versions curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add - # OK echo "deb https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list # deb https://apt.kubernetes.io/ kubernetes-xenial main sudo apt -qq update # All packages are up to date. sudo apt install -yqq kubeadm # The following additional packages will be installed: # conntrack cri-tools ebtables kubectl kubelet kubernetes-cni socat # Suggested packages: # nftables # The following NEW packages will be installed: # conntrack cri-tools ebtables kubeadm kubectl kubelet kubernetes-cni socat # 0 upgraded, 8 newly installed, 0 to remove and 0 not upgraded. # ... sudo apt-mark hold kubelet kubeadm kubectl # kubelet set on hold. # kubeadm set on hold. # kubectl set on hold. # install Kubernetes control plane # generate token for the installation TOKEN=$(sudo kubeadm token generate) echo $TOKEN # rqyytr.f3pvvz2yepq51b7h sudo kubeadm init --token=${TOKEN} --kubernetes-version=v1.19.4 --pod-network-cidr=10.244.0.0/16 # W1208 16:59:02.624049 781 configset.go:348] WARNING: kubeadm cannot validate component configs for API groups [kubelet.config.k8s.io kubeproxy.config.k8s.io] # [init] Using Kubernetes version: v1.19.4 # [preflight] Running pre-flight checks # [WARNING SystemVerification]: missing optional cgroups: hugetlb # [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' # [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 pimaster] and IPs [10.96.0.1 192.168.12.101] # [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 pimaster] and IPs [192.168.12.101 127.0.0.1 ::1] # [certs] Generating "etcd/peer" certificate and key # [certs] etcd/peer serving cert is signed for DNS names [localhost pimaster] and IPs [192.168.12.101 127.0.0.1 ::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" # [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. # [kubelet-check] It seems like the kubelet isn't running or healthy. # [kubelet-check] The HTTP call equal to 'curl -sSL http://localhost:10248/healthz' failed with error: Get "http://localhost:10248/healthz": dial tcp [::1]:10248: connect: connection refused. # [kubelet-check] It seems like the kubelet isn't running or healthy. # [kubelet-check] The HTTP call equal to 'curl -sSL http://localhost:10248/healthz' failed with error: Get "http://localhost:10248/healthz": dial tcp [::1]:10248: connect: connection refused. # [kubelet-check] It seems like the kubelet isn't running or healthy. # [kubelet-check] The HTTP call equal to 'curl -sSL http://localhost:10248/healthz' failed with error: Get "http://localhost:10248/healthz": dial tcp [::1]:10248: connect: connection refused. # [apiclient] All control plane components are healthy after 212.227971 seconds # [upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace # [kubelet] Creating a ConfigMap "kubelet-config-1.19" in namespace kube-system with the configuration for the kubelets in the cluster # [upload-certs] Skipping phase. Please see --upload-certs # [mark-control-plane] Marking the node pimaster as control-plane by adding the label "node-role.kubernetes.io/master=''" # [mark-control-plane] Marking the node pimaster as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule] # [bootstrap-token] Using token: rqyytr.f3pvvz2yepq51b7h # [bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles # [bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to get nodes # [bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials # [bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token # [bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster # [bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace # [kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key # [addons] Applied essential addon: CoreDNS # [addons] Applied essential addon: kube-proxy # # Your Kubernetes control-plane has initialized successfully! # # To start using your cluster, you need to run the following as a regular user: # mkdir -p $HOME/.kube # sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config # sudo chown $(id -u):$(id -g) $HOME/.kube/config # # You should now deploy a pod network to the cluster. # Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at: # https://kubernetes.io/docs/concepts/cluster-administration/addons/ # # Then you can join any number of worker nodes by running the following on each as root: # # kubeadm join 192.168.12.101:6443 --token rqyytr.f3pvvz2yepq51b7h \ # --discovery-token-ca-cert-hash sha256:5b04368aaee148fa3eb8c6aed3c3bc8041248590e2055a81617d16d8f796bb77 # start using the cluster mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config # check node status (something's missing - flannel) kubectl get nodes # NAME STATUS ROLES AGE VERSION # pimaster NotReady master 14m v1.19.4 # install flannel network plugin kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml # podsecuritypolicy.policy/psp.flannel.unprivileged created # clusterrole.rbac.authorization.k8s.io/flannel created # clusterrolebinding.rbac.authorization.k8s.io/flannel created # serviceaccount/flannel created # configmap/kube-flannel-cfg created # daemonset.apps/kube-flannel-ds created # and now we're ready (check under STATUS) kubectl get nodes # NAME STATUS ROLES AGE VERSION # pimaster Ready master 17m v1.19.4 # add node to the cluster (pinode, 192.168.12.102) sudo kubeadm join 192.168.12.101:6443 --token rqyytr.f3pvvz2yepq51b7h --discovery-token-ca-cert-hash sha256:5b04368aaee148fa3eb8c6aed3c3bc8041248590e2055a81617d16d8f796bb77 # [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 -oyaml' # [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. # check nodes in the cluster (check the details... nice) kubectl get nodes -o wide # NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME # pimaster Ready master 18m v1.19.4 192.168.12.101 Raspbian GNU/Linux 10 (buster) 5.4.79-v7+ docker://18.9.1 # pinode Ready 6m15s v1.19.4 192.168.12.102 Ubuntu 20.04.1 LTS 5.4.0-56-generic docker://19.3.8 # test with some workload kubectl apply -f https://k8s.io/examples/application/guestbook/redis-master-deployment.yaml # deployment.apps/redis-master created kubectl get pods # NAME READY STATUS RESTARTS AGE # redis-master-f46ff57fd-9m9g9 1/1 Running 0 37s kubectl apply -f https://k8s.io/examples/application/guestbook/redis-master-service.yaml # service/redis-master created kubectl get service # NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE # kubernetes ClusterIP 10.96.0.1 443/TCP 22m # redis-master ClusterIP 10.100.245.207 6379/TCP 4s kubectl apply -f https://k8s.io/examples/application/guestbook/redis-slave-deployment.yaml # deployment.apps/redis-slave created kubectl get pods # NAME READY STATUS RESTARTS AGE # redis-master-f46ff57fd-9m9g9 1/1 Running 0 2m30s # redis-slave-bbc7f655d-dz895 1/1 Running 0 12s # redis-slave-bbc7f655d-slnhv 1/1 Running 0 12s kubectl apply -f https://k8s.io/examples/application/guestbook/redis-slave-service.yaml # service/redis-slave created kubectl get services # NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE # kubernetes ClusterIP 10.96.0.1 443/TCP 23m # redis-master ClusterIP 10.100.245.207 6379/TCP 91s # redis-slave ClusterIP 10.101.165.188 6379/TCP 13s kubectl apply -f https://k8s.io/examples/application/guestbook/frontend-deployment.yaml # deployment.apps/frontend created kubectl get pods -l app=guestbook -l tier=frontend # NAME READY STATUS RESTARTS AGE # frontend-6c6d6dfd4d-945hd 1/1 Running 0 7s # frontend-6c6d6dfd4d-mm7vm 1/1 Running 0 7s # frontend-6c6d6dfd4d-wllpx 1/1 Running 0 7s kubectl apply -f https://k8s.io/examples/application/guestbook/frontend-service.yaml # service/frontend created kubectl get services # NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE # frontend NodePort 10.101.140.217 80:31597/TCP 4s # kubernetes ClusterIP 10.96.0.1 443/TCP 24m # redis-master ClusterIP 10.100.245.207 6379/TCP 2m45s # redis-slave ClusterIP 10.101.165.188 6379/TCP 87s |
Seems to be working (😊):
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# cleanup kubectl delete deployment -l app=redis # deployment.apps "redis-master" deleted # deployment.apps "redis-slave" deleted kubectl delete service -l app=redis # service "redis-master" deleted # service "redis-slave" deleted kubectl delete deployment -l app=guestbook # deployment.apps "frontend" deleted kubectl delete service -l app=guestbook # service "frontend" deleted kubectl get pods # No resources found in default namespace. |
Cheers!
P.S. I’ve read about some having issues with flannel and using other network options (didn’t have this one). Also, if you’ll have issues with iptables (v1.8+), maybe you’ll need to switch to legacy version (didn’t have this one either).