{"id":7959,"date":"2019-12-06T09:41:43","date_gmt":"2019-12-06T09:41:43","guid":{"rendered":"https:\/\/www.devopsschool.com\/blog\/?p=7959"},"modified":"2021-11-15T09:45:07","modified_gmt":"2021-11-15T09:45:07","slug":"detailed-explaination-of-joining-kubernetes-nodes-aka-workers-in-kubernetes-master","status":"publish","type":"post","link":"https:\/\/www.devopsschool.com\/blog\/detailed-explaination-of-joining-kubernetes-nodes-aka-workers-in-kubernetes-master\/","title":{"rendered":"Detailed explaination of joining Kubernetes Nodes aka workers in Kubernetes master?"},"content":{"rendered":"\n

Step 1 – Install Docker <\/strong>
https:\/\/www.devopsschool.com\/tutorial\/docker\/install-config\/
https:\/\/www.devopsschool.com\/tutorial\/docker\/install-config\/docker-install-commuityedition-centos-rhel.html<\/p>\n\n\n

Here\u2019s the skeleton of a kubeadm join command for a control plane node:\nkubeadm join <endpoint-ip-or-dns<\/span>><\/span>:<port<\/span>><\/span> \\\n--token <valid-bootstrap-token<\/span>><\/span> \\\n--discovery-token-ca-cert-hash <ca-cert-sha256-hash<\/span>><\/span> \\\n--control-plane \\\n--certificate-key <certificate-key<\/span>><\/span>\n\nAnd here\u2019s the skeleton of a kubeadm join command for a worker node:\nkubeadm join <endpoint-ip-or-dns<\/span>><\/span>:<port<\/span>><\/span> \\\n--token <valid-bootstrap-token<\/span>><\/span> \\\n--discovery-token-ca-cert-hash <ca-cert-sha256-hash<\/span>><\/span> \\<\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
Step 2 – How to find discovery-token-ca-cert-has in kubernetes master node?<\/strong><\/p>\n\n\n\n
Mehtod 1 – Using openssl<\/strong><\/p>\n\n\n
\n\nopenssl x509 -in<\/span> \/etc\/kubernetes\/pki\/ca.crt -pubkey -noout | openssl pkey -pubin -outform DER | openssl dgst -sha256\nor\nopenssl x509 -pubkey -in<\/span> \/etc\/kubernetes\/pki\/ca.crt | openssl rsa -pubin -outform der 2<\/span>>\/dev\/<\/span>null<\/span> | openssl dgst -sha256 -hex | sed 's\/^.* \/\/'<\/span><\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
Method 2 – Using Ansible Python Filter<\/strong><\/p>\n\n\n\n
Reference – https:\/\/gist.github.com\/randomvariable\/e4c43f89afec52fec0dbef6c08621249<\/p>\n\n\n\n
Step 3 – How to Gererate kubeadm join “kubeadm token” using kubeadm in master nodes?<\/strong><\/p>\n\n\n\n
Bootstrap tokens are used for establishing bidirectional trust between a node joining the cluster and a control-plane node, as described in authenticating with bootstrap tokens. The duration before the token is automatically deleted (e.g. 1s, 2m, 3h). If set to ‘0’, the token will never expire (default 24h0m0s)<\/p>\n\n\n\n
Differenece between kubeadm token create and kubeadm token generate
 “kubeadm token create” would Create bootstrap tokens on the server but “kubeadm token generate” would Generate and print a bootstrap token, but do not create it on the server. <\/p>\n\n\n\n
kubeadm token generate<\/strong>
 This command will print out a randomly-generated bootstrap token that can be used with the \u201cinit\u201d and \u201cjoin\u201d commands. You can also use \u201ckubeadm init\u201d without specifying a token and it will generate and print one for you. The duration before the token is automatically deleted (e.g. 1s, 2m, 3h). If set to ‘0’, the token will never expire (default 24h0m0s)<\/p>\n\n\n\n
Create a kubeadm token for 200 hours?<\/strong>
 $ kubeadm token create –ttl 24h0m0s<\/p>\n\n\n\n
Generate a kubeadm token for life time?<\/strong>
 $ kubeadm token create –ttl 0<\/p>\n\n\n\n
Step 4 – Replace “172.31.14.69:6443” with API server.  –token with kubeadm token and  –discovery-token-ca-cert-hash and run following.<\/strong><\/p>\n\n\n
\n$ kubeadm join 172.31.14.69:6443 --token w82oxl.jglf7o8s7c2k4u8x --discovery-token-ca-cert-hash sha256:25d17cb97848f19c5ff6a097d5c18d410d41bff9a4b69cb9885be1ad26caeb16\n<\/code><\/span><\/pre>\n\n