dreamcloud/ubuntu18-k8s is my k8s dev ready box, here is demo to show how to launch a 2 nodes k8s cluster in few mins using vagrant.
tool set
My test env is on win10, command line running on wsl ubuntu, pre-installed below tools:
- Vagrant 2.2.10
- Virtualbox 6.1
prepare Vagrantfile
You can download pre-configed Vagrantfile from here,
$ mkdir /mnt/c/vagrant/ub18k8s $ curl -LO https://raw.githubusercontent.com/robertluwang/dreamcloud-vagrant/master/ubuntu18-k8s/Vagrantfile
assume the k8s cluster setting:
- k8s-master 192.168.20.23 CPUx2 RAM 4G
- k8s-node 192.168.20.24 CPUx2 RAM 2G
- pod network: calico
launch k8s cluster from vagrant box
/mnt/c/vagrant/ub18k8s$ vagrant.exe up /mnt/c/vagrant/ub18k8s$ vagrant.exe status Current machine states: k8s-master running (virtualbox) k8s-node running (virtualbox)
k8s cluster is ready
vagrant@k8s-master:~$ kubectl get nodes NAME STATUS ROLES AGE VERSION k8s-master Ready master 50m v1.19.0 k8s-node Ready 49m v1.19.0 vagrant@k8s-node:~$ kubectl get nodes NAME STATUS ROLES AGE VERSION k8s-master Ready master 81m v1.19.0 k8s-node Ready 79m v1.19.0
k8s health check
systemctl status kubelet kubeadm config print init-defaults kubectl config view kubectl describe node k8s-master kubectl get nodes -o wide kubectl get pods --all-namespaces
common issue and remedy
vagrant NIC
There are two NICs used in vagrant: – NAT for internet access, default is 10.0.2.15 – Host-only for internal network, 192.168.20.0/24 By default kubeadm always picked up NAT ip as etcd interface, however all vagrant vm has same ip and cannot talk each other using NAT.
[certs] etcd/peer serving cert is signed for DNS names [localhost k8s-master] and IPs [10.0.2.15 127.0.0.1 ::1]
As remedy, need to use option –apiserver-advertise-address
sudo kubeadm init --pod-network-cidr=192.168.0.0/16 --apiserver-advertise-address=192.168.20.23 | tee /tmp/kubeadm.log
cannot run kubectl on worker node
The connection to the server localhost:8080 was refused - did you specify the right host or port?
The issue is lack of env setting on worker, which is from admin.config but it only generated when kubeadm init on master, so need to transfer to each worker and setup similar as on master,
mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config this is what I did, mkdir -p $HOME/.kube scp -q -o StrictHostKeyChecking no -i $HOME/.ssh/vagrant k8s-master:$HOME/.kube/config $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config
kubeadm join on worker
The token is for 2 hours, since I launch k8s cluster from Vagrantfile for few test nodes in lab, assume whole setup work will be done less than 2 hours, so I just save token as log file on master and fetch from worker then run it, it is fair enough for dev lab.
scp -q -o StrictHostKeyChecking no -i $HOME/.ssh/vagrant k8s-master:/tmp/kubeadm.log /tmp/kubeadm.log
token=$(cat /tmp/kubeadm.log |grep kubeadm join|head -1 |awk -Ftoken \'{print $2}\'|awk \'{print $1}\')
certhash=$(cat /tmp/kubeadm.log |grep discovery-token-ca-cert-hash|tail -1|awk \'{print $2}\')
sudo kubeadm join k8s-master:6443 --token $token --discovery-token-ca-cert-hash $certhash
So far the a two nodes k8s cluster already setup and running.
cli completion
There are so many subcommand options for k8s cli, so cli completion feature will save lots of time during test and work.
sudo apt-get install bash-completion -y source <(kubectl completion bash) echo 'source <(kubectl completion bash)' >> ~/.bashrc
conclusion
We learned how to launch 2 nodes k8s cluster using pre-build k8s vagrant image in few mins, and solved few common issues on setup configuration.