Kubernetes is a container orchestrator for managing high scale deployment challenges
Architecture #
The kubernetes cluster architecture presents itself as follows:
Where the control plane node manages the worker nodes that run pods, pods are managed trough a container runtime (for example containerd) that runs the containers, the control plane is also responsible for managing deployments
Networking in a kubernetes cluster #
Containers and pods share a private network stack that allow them to communicate inside the cluster, and a name service
Deployment in a kubernetes cluster #
Deployment on a kubernetes cluster is done trough the use of the api server using a descriptor that specifies:
- containers
- images
- replicas
- volumes
- configurations
ℹ️ Note
pods are the minimum unit of deployment in kubernetes
Installation using kubeadm
#
To install the control plane on a linux machine do the following (package manager updates are locked)
sudo apt-get update
sudo apt-get install -y apt-transport-https ca-certificates curl gpg
echo 'deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.32/deb/ /' | sudo tee /etc/apt/sources.list.d/kubernetes.list
sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl
This will install necessary components on a node to run the control plane, then initialize the cluster using the kubeadm command
# enable forwarding
sysctl net.ipv4.ip_forward=1 && echo 'net.ipv4.ip_forward=1' >> /etc/sysctl.conf
# install containerd
apt install containerd
# init kluster
kubeadm init
Configuring worker nodes #
In worker nodes after installing the kubeadm tool, init the kubelet process
systemctl enable --now kubelet
Then join the kluster using kubeadm join command
