I have set up my master node and I am trying to join a worker node as follows:
kubeadm join 192.168.30.1:6443 --token 3czfua.os565d6l3ggpagw7 --discovery-token-ca-cert-hash sha256:3a94ce61080c71d319dbfe3ce69b555027bfe20f4dbe21a9779fd902421b1a63However the command hangs forever in the following state:
[preflight] Running pre-flight checks
[WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/Since this is just a warning, why does it actually fails?
edit: I noticed the following in my /var/log/syslog
Mar 29 15:03:15 ubuntu-xenial kubelet[9626]: F0329 15:03:15.353432 9626 server.go:193] failed to load Kubelet config file /var/lib/kubelet/config.yaml, error failed to read kubelet config file "/var/lib/kubelet/config.yaml", error: open /var/lib/kubelet/config.yaml: no such file or directory
Mar 29 15:03:15 ubuntu-xenial systemd[1]: kubelet.service: Main process exited, code=exited, status=255/n/a
Mar 29 15:03:15 ubuntu-xenial systemd[1]: kubelet.service: Unit entered failed state.
I had a bunch of k8s deployment scripts that broke recently with this same error message... it looks like docker changed it's install. Try this --
previous install: apt-get isntall docker-ce
updated install: apt-get install docker-ce docker-ce-cli containerd.io
I did get the same error on CentOS 7 but in my case join command worked without problems, so it was indeed just a warning.
> [WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker
> cgroup driver. The recommended driver is "systemd". Please follow the
> guide at https://kubernetes.io/docs/setup/cri/ [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] Downloading configuration for the kubelet from the "kubelet-config-1.14" ConfigMap in the kube-system namespaceAs the official documentation mentions, there are two common issues that make the init hang (I guess it also applies to join command):
the default cgroup driver configuration for the kubelet differs from that used by Docker. Check the system log file (e.g. /var/log/message) or examine the output from journalctl -u kubelet. If you see something like the following:
First try the steps from official documentation and if that does not work please provide more information so we can troubleshoot further if needed.
First if you want to see more detail when your worker joins to the master use:
kubeadm join 192.168.1.100:6443 --token m3jfbb.wq5m3pt0qo5g3bt9 --discovery-token-ca-cert-hash sha256:d075e5cc111ffd1b97510df9c517c122f1c7edf86b62909446042cc348ef1e0b --v=2Using the above command I could see that my worker could not established connection with the master, so i just stoped the firewall:
systemctl stop firewalld The problem had to do with kubeadm not installing a networking CNI-compatible solution out of the box;
Therefore, without this step the kubernetes nodes/master are unable to establish any form of communication;
The following task addressed the issue:
- name: kubernetes.yml --> Install Flannel
shell: kubectl -n kube-system apply -f https://raw.githubusercontent.com/coreos/flannel/bc79dd1505b0c8681ece4de4c0d86c5cd2643275/Documentation/kube-flannel.yml
become: yes
environment:
KUBECONFIG: "/etc/kubernetes/admin.conf"
when: inventory_hostname in (groups['masters'] | last)