Styjun

I have set up my master nodes using kubeadm.

Now I want to run the join command on my nodes so that the later join the cluster.

All I have to do is run

kubeadm join --token <token> --discovery-token-ca-cert-hash <sha256>

where <token> and are values previously returned by the command below:

kubeadm init 

I am also trying to script the above process and I see that parsing the actual tokens from the last command is kinda difficult;

So I was wandering whether there is a way to explicitly specify the <token> and the <sha256> during cluster initialization, to avoid having to perform hacky parsing of the init command.

I was trying to make a script for it as well.

In order to get the values needed I am using these commands:

TOKEN=$(sshpass -p $PASSWORD ssh -o StrictHostKeyChecking=no root@$MASTER_IP sudo kubeadm token list | tail -1 | cut -f 1 -d " ") 


HASH=$(sshpass -p $PASSWORD ssh -o StrictHostKeyChecking=no root@$MASTER_IP openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //' )

Basically I use this commands to ssh on master and get this values.

I have not found a easier way to achieve this.

Actually there seems to be a way around this:

(I am putting this in ansible tasks cause this is where I am planning to use it)

 - name: kubernetes.yml --> Initiate kubernetes cluster
 shell: 'kubeadm init --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address= ansible_facts[if_name]["ipv4"]["address"] '
 become: yes
 when: inventory_hostname in groups['masters']


 - name: kubernetes.yml --> Get the join command
 shell: kubeadm token create --print-join-command
 register: rv_join_command
 when: inventory_hostname in (groups['masters'] | last)
 become: yes

 - name: kubernetes.yml --> Print the join command
 debug:
 var: rv_join_command.stdout

Output:

TASK [kubernetes.yml --> Print the join command] *******************************
ok: [kubernetes-master-1] => 
 rv_join_command.stdout: 'kubeadm join 192.168.30.1:6443 --token ah0dbr.grxg9fke3c28dif3i --discovery-token-ca-cert-hash sha256:716712ca7f07bfb4aa7df9a8b30ik3t0k3t2259b8c6fc7b68f50334356078 '