Kubernetes is deprecating Docker
Kubernetes cluster setup with containerd runtime
In this blog, we will see the only implementation of containerd in the Kubernetes cluster. As there are lots of links available on the reason behind Kubernetes deprecating the docker.
As we know Kubernetes is deprecating the docker in the upcoming release later in 2021, we should know how to set up the Kubernetes cluster using the containerd. As containerd is the second most popular container runtime.
The Kubernetes will only deprecate the container runtime interface. Docker produced images will still continue to work in your cluster with all runtimes, as they always have. There is no need to worry about which container images, which container registry, which tool should I use to build the container Images. Docker is still a useful tool for building containers, and the images that result from running docker build can still run in your Kubernetes cluster.
What you will need:
One ubuntu Desktop/server 16/18.04 with sudo access:
Implementation:
Steps to install containerd runtime environment
Use the below command to install containerd on the Ubuntu server:
#sudo apt-get update
#sudo apt-get install containerd -y
Configure containerd using below commands:
#sudo mkdir -p /etc/containerd
#sudo su -
#containerd config default /etc/containerd/config.toml
Steps to install kubernetes packages:
To add the gpg-key:
#curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -
To add the repo:
#echo ‘deb http://apt.kubernetes.io/ kubernetes-xenial main’ | sudo tee /etc/apt/sources.list.d/kubernetes.list
#apt-get update -y
To install Kubernetes related packages:
#apt-get install kubelet kubeadm kubectl -y
After installing the docker we don’t need to do any additional configuration as it does automatically. But after installing containerd we have to do some manual configuration using the below commands to load modules requires for containerd:
#sudo cat <<EOF | sudo tee /etc/modules-load.d/containerd.conf
overlay
br_netfilter
EOF
#sudo modprobe overlay
#sudo modprobe br_netfilter
Setup required sysctl parameters, these persist across reboot:
#cat <<EOF | sudo tee /etc/sysctl.d/99-kubernetes-cri.conf
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF
Apply sysctl parameters without reboot:
#sudo sysctl — system
Configure Kubernetes cluster for using containerd runtime environment:
User below command to initialize the kubernetes cluster:
#sudo kubeadm init — cri-socket /run/containerd/containerd.sock — pod-network-cidr=10.244.0.0/16
#sudo mkdir -p $HOME/.kube
#sudo cp -rf /etc/kubernetes/admin.conf $HOME/.kube/config
#sudo chown $(id -u):$(id -g) $HOME/.kube/config
Deploy pod network using below command:
#sudo kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
The below fig. shows command output that indicates Kubernetes cluster is configured with containerd runtime environment:
#kubectl get nodes -owide
Verify kube-system pod running or not using the below command:
Congratulations, We have successfully configured the Kubernetes cluster using containerd runtime.
Deploy Nginx web server in this containerd runtime environment Kubernetes cluster using the docker image.
Important:
In this blog, To operate containers and images in containerd runtime environment Kubernetes clusters, we will use crictl command-line tools. The images pulled by using the docker command will not run in the Kubernetes cluster. You have to pull docker images using crictl command then and then the only docker created images will run in the Kubernetes cluster created by using the containerd runtime environment. Crictl command has come already after installation of containerd in our machine.
To work with crictl command line tool fire below command
#sudo cat <<EOF > /etc/crictl.yaml
runtime-endpoint: unix:///var/run/containerd/containerd.sock
image-endpoint: “”
timeout: 0
debug: false
EOF
Check docker images present on your machine using the below command:
#sudo crictl images
To pull Nginx docker image use below command
#sudo crictl pull nginx
Use the below deployment file to deploy the Nginx web server.
#cat <<EOF > nginx.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
replicas: 1
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx
imagePullPolicy: IfNotPresent
ports:
- containerPort: 80
— -
apiVersion: v1
kind: Service
metadata:
name: nginx
labels:
app: nginx
spec:
type: NodePort
ports:
- port: 80
nodePort: 30010
selector:
app: nginx
EOF
Deploy nginx web app using below command:
#Kubectl apply -f nginx.yaml
Check app is running on below URL:
Some useful commands:
To check docker images:
#crictl images
To check running containers:
#crictl ps
To pull docker images:
#crictl pull IMAG_ENAME
To pull docker images from the private repository:
#crictl pull — creds $registry_username:$registry_pass IMAGE_NAME
Conclusion:
In this blog, we have seen the implementation of containerd in the Kubernetes cluster as we know Kubernetes is deprecating the docker in the upcoming release.
