k3s stand-alone installation deployment with one click installation script

k8s VS k3s

k3s yes Rancher Launched lightweight k8s. K3s itself contains the source code of k8s, while the binary package is only 60M, but it is essentially no different from k8s. However, in order to reduce resource occupation, there are some differences between k3s and k8s, mainly:

  • Lighter than Docker containerd Run as a container (Docker is not the only container choice).
  • The legacy, alpha and non default features of k8s are removed.
  • Use sqlite3 as the default storage instead of etcd.
  • For other optimizations, k3s is only a binary file, which is very easy to deploy

So k3s it is suitable for resource constrained scenarios such as edge computing and IoT. At the same time, k3s is also very easy to deploy. It is available on the official website One click deployment script.

Advantages of k3s

  • k3s packages everything necessary to install Kubernetes into a binary file of only 60MB size, and fully implements the Kubernetes API. In order to reduce the memory required to run Kubernetes, Rancher removed many unnecessary drivers and replaced them with add-on components.
  • K3s is a fully CNCF certified Kubernetes distribution, which means that you can write YAML to operate on the full version of Kubernetes, and they will also be applicable to k3s clusters.
  • Because it only needs very low resources to run, it can run the cluster on any device with more than 512MB RAM. In other words, we can let the pod run on the master and nodes.

Disadvantages of k3s

  • First of all, the current version of k3s (k3s v0.8.1) can only run a single master, which means that if your Master goes down, you cannot manage your cluster, even if the existing cluster continues to run. However, in k3s v0.10, multi master mode is already an experimental function, and GA may be available in the next version.
  • Secondly, in the k3s of a single master, the default data store is SQLite, which is very friendly to small databases, but if it is hit hard, SQLite will become the main pain point. However, the changes in the Kubernetes control plane are more related to frequent update deployment, scheduling Pod, etc. Therefore, the database will not cause too much load for small development / test clusters.

conclusion

K8s and k3s have their own advantages and disadvantages, and their use scenarios are also different, so they can not be generalized. If you want to carry out large-scale cluster deployment, I suggest you choose k8s;

If you just want to develop or test like me, choosing k3s is a more cost-effective choice.

Installation k3s

Make sure you are a clean CentOS7 server.
Update first according to the Convention. Change the source to the domestic yum source before updating.

# Change domestic yum source
curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
curl -o /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo
# to update
yum update -y

Modify host name

hostnamectl  set-hostname  k3s-master

After modification, disconnect and reconnect.
{{< alert theme="warning" dir="ltr" >}}
⚠️ be careful
K3s will use Containerd as the container environment by default. Please select Docker installation or container installation below.
{{< /alert >}}
{{< tabs install using docker install using containerd >}}
{{< tab >}}

Installing using docker

# Install docker CE
yum remove -y docker docker-client docker-client-latest docker-common docker-latest docker-latest-logrotate docker-logrotate docker-engine
yum install -y yum-utils
yum-config-manager --add-repo  https://download.docker.com/linux/centos/docker-ce.repo
yum install -y docker-ce docker-ce-cli containerd.io
# Solve the kernel check problem and restart to take effect
grubby --args="user_namespace.enable=1" --update-kernel="$(grubby --default-kernel)"
systemctl enable docker
systemctl start docker
# Modify docker source
cat << EOF > /etc/docker/daemon.json
{
    "registry-mirrors":["https://3laho3y3.mirror.aliyuncs.com"]
}
EOF
systemctl daemon-reload
systemctl restart docker
# End of docker installation
# Turn off firewalld firewall
systemctl stop firewalld
systemctl disable firewalld
# Installation k3s
curl -sfL http://rancher-mirror.cnrancher.com/k3s/k3s-install.sh | INSTALL_K3S_MIRROR=cn sh -s - --docker

{{< /tab >}}
{{< tab >}}

Installing using containerd

curl -sfL http://rancher-mirror.cnrancher.com/k3s/k3s-install.sh | INSTALL_K3S_MIRROR=cn sh -

{{< /tab >}}
{{< /tabs >}}

Inspection after installation

After the installation is completed, you can execute the following command to check the host.

# Run configuration check
k3s check-config
# View node status and k3s version
[root@k3s-master ~]# kubectl get node
NAME             STATUS   ROLES                  AGE   VERSION
vm-16-8-centos   Ready    control-plane,master   52m   v1.21.5+k3s2
# View all pod information
[root@k3s-master ~]# kubectl get pods -A
NAMESPACE     NAME                                      READY   STATUS      RESTARTS   AGE
kube-system   local-path-provisioner-5ff76fc89d-bbps4   1/1     Running     0          52m
kube-system   coredns-7448499f4d-42v9x                  1/1     Running     0          52m
kube-system   metrics-server-86cbb8457f-xqlrg           1/1     Running     0          52m
kube-system   helm-install-traefik-crd-9wk9v            0/1     Completed   0          52m
kube-system   helm-install-traefik-d8llf                0/1     Completed   3          52m
kube-system   svclb-traefik-jqxvf                       2/2     Running     0          49m
kube-system   traefik-97b44b794-wv6zv                   1/1     Running     0          49m

As of now, k3s has been installed.

Installing nfs

Installing nfs services

yum -y install nfs-utils
systemctl start nfs && systemctl enable nfs

Create nfs directory

mkdir -p /home/k8s/nfs

Modify permissions

chmod -R 755 /home/k8s/nfs

Edit export file

cat >>/etc/exports << EOF
/home/k8s/nfs *(rw,no_root_squash,sync)
EOF

Configuration effective

exportfs -r

Start rpcbind and nfs services

systemctl restart rpcbind && systemctl enable rpcbind
systemctl restart nfs && systemctl enable nfs

Here, k3s and nfs have been installed. Now you can experience it.
If you want to make the above more troublesome, you can use the following one click installation script to execute

One click installation k3s script

#!/bin/bash
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH
LANG=en_US.UTF-8

RD="\033[31m"      # Error message
GR="\033[32m"      # Success message
YL="\033[33m"      # Alarm message
BL="\033[36m"      # Log message
PL='\033[0m'

clear
echo -e "${YL}##################################################${PL}"
echo -e "${YL}#${PL} ${GR}Script name ${PL}: One click installation k3s script                    ${YL}#${PL}"
echo -e "${YL}#${PL} ${GR}do    person ${PL}: sre Operation and maintenance blog                          ${YL}#${PL}"
echo -e "${YL}#${PL} ${GR}network    site ${PL}: https:www.cnsre.cn                   ${YL}#${PL}"
echo -e "${YL}#${PL} ${GR}Article address ${PL}: https://cnsre.cn/posts/211109907029/ ${YL}#${PL}"
echo -e "${YL}##################################################${PL}"
sleep 0.5

set -e
echo  
echo 
echo
echo -e "${RD}Are you sure you want to install dockerb Version k3s? ${PL}"
read -r -p "To confirm, press y Any key will exit! Please select:[y/n]" input
    if [[ $input != "y" ]]; then
        exit 1
    else 
        echo -e "$GR Starting installation dockerb Version k3s$PL"
    fi

if [ `command -v docker` ];then
    echo -e "${YL}docker Already installed,Adding docker Acceleration source ${PL}"
else
    echo -e "${GR}install docker${PL}"
    curl https://download.daocloud.io/docker/linux/centos/docker-ce.repo -o /etc/yum.repos.d/docker-ce.repo
    yum -y install https://download.daocloud.io/docker/linux/centos/7/x86_64/stable/Packages/containerd.io-1.2.6-3.3.el7.x86_64.rpm
    curl -fsSL https://get.daocloud.io/docker | bash -s docker --mirror Aliyun
fi

sudo mkdir -p /etc/docker
tee /etc/docker/daemon.json <<-'EOF'
{
  "registry-mirrors": ["http://f1361db2.m.daocloud.io"]
}
EOF
grubby --args="user_namespace.enable=1" --update-kernel="$(grubby --default-kernel)"

sudo systemctl daemon-reload
sudo systemctl restart docker
sudo systemctl enable docker


if [ `command -v k3s` ];then
    echo -e "${YL}k3s Already installed ${PL}"
    exit 1
else
    export K3S_NODE_NAME=${HOSTNAME//_/-}
    export INSTALL_K3S_EXEC="--docker --kube-apiserver-arg service-node-port-range=1-65000 --no-deploy traefik --write-kubeconfig ~/.kube/config --write-kubeconfig-mode 666"
    curl -sfL http://rancher-mirror.cnrancher.com/k3s/k3s-install.sh | INSTALL_K3S_MIRROR=cn sh -
fi

echo -e "${GR}export K3S_TOKEN=$(cat /var/lib/rancher/k3s/server/node-token)${PL}"
echo -e "${GR}export K3S_URL=https://$(ip addr | grep -E -o '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' | grep -E -v "^127\.|^255\.|^0\." | head -n 1):6443${PL}"
echo -e "${GR}After installation, please restart the server ${PL}"
read -r -p "To confirm, press y Any key will exit! Please select:[y/n]" input
    if [[ $input != "y" ]]; then
        reboot
    else 
        exit 1
    fi

Tags: Linux Kubernetes

Posted on Tue, 09 Nov 2021 22:35:51 -0500 by mariom

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