The size is only 40MB k3s developed and tested for the companies want to save money provides a good choice. This article will use a very simple way, teach you to use k3s deploy lightweight Kubernetes cluster within five minutes.
Kubernetes has changed how the large-scale deployment and management of container workloads. Now the main challenge facing developers is enormous demand for resources and the complexity of the setup process. If you are plagued by insufficient memory, you want to deploy lightweight Kubernetes clusters to reduce the memory footprint, then you should definitely consider a lightweight Kubernetes release --k3s issued by Rancher Labs. It is everything you need to install Kubernetes are packaged into a binary file size of 40MB, the only RAM 512MB to run. Very suitable for resource-limited environment, such as edge computing scenarios, the IoT and the like.
In the actual scene, in order to obtain power development and testing, save money, the user would like to have minimal resource utilization and lower hardware specifications to deploy Kubernetes. And k3s just to meet this demand, it can run on any of the above cluster 512MB RAM device, such as a device or ARM IoT driving device.
Since k3s only a few resources to run, then this means that some properties were removed Kubernetes:
The old, non-default, alpha function
Most in-tree widget (cloud provider and memory card), which will be replaced with additional components
Sqlite instead by default storage mechanism etcd
Use k3s deploy lightweight K8s cluster within five minutes
In this article, I will use Debian 10 run on three server, each server has 1GB of RAM and 1vcpu. Wherein a server as a master, as two other worker nodes.
$ openstack server list
+--------------------------------------+-------------------+---------+-----------------------------------+-----------+-----------+
| ID | Name | Status | Networks | Image | Flavor |
+--------------------------------------+-------------------+---------+-----------------------------------+-----------+-----------+
| 4df6a6dc-26e8-4ae0-8b6e-2f97daec0ef3 | k3s-master | ACTIVE | private=10.10.1.159 | Debian-10 | m1.tiny |
| 5ca13239-b745-4f62-ab11-0a27949c9b35 | k3s-node02 | ACTIVE | private=10.10.1.142 | Debian-10 | m1.tiny |
| a54997f2-4d94-4718-86ab-73609b328761 | k3s-node01 | ACTIVE | private=10.10.1.126 | Debian-10 | m1.tiny |
+--------------------------------------+-------------------+---------+-----------------------------------+-----------+-----------+I will be in each server / etc / hoststo add A record for the file server.
sudo tee -a /etc/hosts<<EOF
10.10.1.159 k3s-master
10.10.1.126 k3s-node01
10.10.1.142 k3s-node02
EOFMounted on the Master node k3s
There are many ways to run k3s, the fastest way is to install via a bash script provided, while the script provides a convenient way to install systemd or openrc.
curl -sfL https://get.k3s.io | sh -Installation output:
[INFO] Finding latest release
[INFO] Using v0.8.1 as release
[INFO] Downloading hash https://github.com/rancher/k3s/releases/download/v0.8.1/sha256sum-amd64.txt
[INFO] Downloading binary https://github.com/rancher/k3s/releases/download/v0.8.1/k3s
[INFO] Verifying binary download
[INFO] Installing k3s to /usr/local/bin/k3s
[INFO] Creating /usr/local/bin/kubectl symlink to k3s
[INFO] Creating /usr/local/bin/crictl symlink to k3s
[INFO] Creating /usr/local/bin/ctr symlink to k3s
[INFO] Creating killall script /usr/local/bin/k3s-killall.sh
[INFO] Creating uninstall script /usr/local/bin/k3s-uninstall.sh
[INFO] env: Creating environment file /etc/systemd/system/k3s.service.env
[INFO] systemd: Creating service file /etc/systemd/system/k3s.service
[INFO] systemd: Enabling k3s unit
Created symlink /etc/systemd/system/multi-user.target.wants/k3s.service → /etc/systemd/system/k3s.service.
[INFO] systemd: Starting k3sAfter the installation is complete, the service will start automatically.
$ systemctl status k3s
● k3s.service - Lightweight Kubernetes
Loaded: loaded (/etc/systemd/system/k3s.service; enabled; vendor preset: enabled)
Active: active (running) since Tue 2019-09-17 19:20:00 UTC; 2min 24s ago
Docs: https://k3s.io
Process: 833 ExecStartPre=/sbin/modprobe br_netfilter (code=exited, status=0/SUCCESS)
Process: 836 ExecStartPre=/sbin/modprobe overlay (code=exited, status=0/SUCCESS)
Main PID: 837 (k3s-server)
Tasks: 98
Memory: 571.1M
CGroup: /system.slice/k3s.service
├─ 837 /usr/local/bin/k3s server KillMode=process
├─ 851 containerd -c /var/lib/rancher/k3s/agent/etc/containerd/config.toml -a /run/k3s/containerd/containerd.sock --state /run/k3s/conta
├─1110 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/f6eeb59978
├─1127 /pause
├─1207 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/0baf0ca181
├─1225 /coredns -conf /etc/coredns/Corefile
├─1576 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/dcce4b7e17
├─1594 /pause
├─1599 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/50816ffba8
├─1617 /pause
├─1824 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/d0ff393609
├─1842 /bin/sh /usr/bin/entry
├─1882 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/046779175f
├─1899 /bin/sh /usr/bin/entry
├─1904 containerd-shim -namespace k8s.io -workdir /var/lib/rancher/k3s/agent/containerd/io.containerd.runtime.v1.linux/k8s.io/93f0fe2361
└─1921 /traefik --configfile=/config/traefik.toml
Sep 17 19:20:34 deb10 k3s[837]: E0917 19:20:34.714229 837 daemon_controller.go:302] kube-system/svclb-traefik failed with : error storing statu
Sep 17 19:20:34 deb10 k3s[837]: E0917 19:20:34.719452 837 daemon_controller.go:302] kube-system/svclb-traefik failed with : error storing statu
Sep 17 19:20:34 deb10 k3s[837]: I0917 19:20:34.726816 837 reconciler.go:207] operationExecutor.VerifyControllerAttachedVolume started for volum
Sep 17 19:20:34 deb10 k3s[837]: I0917 19:20:34.726836 837 reconciler.go:207] operationExecutor.VerifyControllerAttachedVolume started for volum
Sep 17 19:20:34 deb10 k3s[837]: I0917 19:20:34.726857 837 reconciler.go:207] operationExecutor.VerifyControllerAttachedVolume started for volum
Sep 17 19:20:34 deb10 k3s[837]: I0917 19:20:34.726869 837 reconciler.go:207] operationExecutor.VerifyControllerAttachedVolume started for volum
Sep 17 19:20:35 deb10 k3s[837]: I0917 19:20:35.529102 837 reconciler.go:181] operationExecutor.UnmountVolume started for volume "helm-traefik-t
Sep 17 19:20:35 deb10 k3s[837]: I0917 19:20:35.542858 837 operation_generator.go:799] UnmountVolume.TearDown succeeded for volume "kubernetes.i
Sep 17 19:20:35 deb10 k3s[837]: I0917 19:20:35.629277 837 reconciler.go:285] Volume detached for volume "helm-traefik-token-kjwrl" (UniqueName:
Sep 17 19:20:36 deb10 k3s[837]: W0917 19:20:36.355273 837 pod_container_deletor.go:75] Container "2f0c4a787b13c029d65aa865c1b473f5a7497cb6f9b92将kubeconfig文件写入/etc/rancher/k3s/k3s.yaml：
$ cat /etc/rancher/k3s/k3s.yaml
cat: /etc/rancher/k3s/k3s.yaml: Permission denied
debian@deb10:~$ sudo cat /etc/rancher/k3s/k3s.yaml
apiVersion: v1
clusters:
- cluster:
certificate-authority-data: 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
server: https://localhost:6443
name: default
contexts:
- context:
cluster: default
user: default
name: default
current-context: default
kind: Config
preferences: {}
users:
- name: default
user:
password: 2d99cae31c075743be704bb717ceaae8
username: admin其他已经安装的有：
kubectl
crictl
k3s-killall.sh
k3s-uninstall.sh
在Worker节点上安装k3s
要在Woker节点上安装k3s，我们应该将K3S_URL以及K3S_TOKEN或K3S_CLUSTER_SECRET环境变量一起传递。
K3S_TOKEN在第一个节点上的/ var / lib / rancher / k3s / server / node-token中创建。
$ sudo cat /var/lib/rancher/k3s/server/node-token
K1042e2f8e353b9409472c1e0cca8457abe184dc7be3f0805109e92c50c193ceb42::node:c83acbf89a7de7026d6f6928dc270028所以为了在worker节点上安装Kubernetes，我将运行：
k3s_url="https://k3s-master:6443"
k3s_token="K1042e2f8e353b9409472c1e0cca8457abe184dc7be3f0805109e92c50c193ceb42::node:c83acbf89a7de7026d6f6928dc270028"
curl -sfL https://get.k3s.io | K3S_URL=${k3s_url} K3S_TOKEN=${k3s_token} sh -安装输出：
[INFO] Finding latest release
[INFO] Using v0.8.1 as release
[INFO] Downloading hash https://github.com/rancher/k3s/releases/download/v0.8.1/sha256sum-amd64.txt
[INFO] Downloading binary https://github.com/rancher/k3s/releases/download/v0.8.1/k3s
[INFO] Verifying binary download
[INFO] Installing k3s to /usr/local/bin/k3s
[INFO] Creating /usr/local/bin/kubectl symlink to k3s
[INFO] Creating /usr/local/bin/crictl symlink to k3s
[INFO] Creating /usr/local/bin/ctr symlink to k3s
[INFO] Creating killall script /usr/local/bin/k3s-killall.sh
[INFO] Creating uninstall script /usr/local/bin/k3s-agent-uninstall.sh
[INFO] env: Creating environment file /etc/systemd/system/k3s-agent.service.env
[INFO] systemd: Creating service file /etc/systemd/system/k3s-agent.service
[INFO] systemd: Enabling k3s-agent unit
Created symlink /etc/systemd/system/multi-user.target.wants/k3s-agent.service → /etc/systemd/system/k3s-agent.service.
[INFO] systemd: Starting k3s-agent登录到其中一个master节点并检查集群状态：
$ sudo kubectl config get-clusters
NAME
default
$ sudo kubectl cluster-info
Kubernetes master is running at https://localhost:6443
CoreDNS is running at https://localhost:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
$ sudo kubectl get nodes
NAME STATUS ROLES AGE VERSION
k3s-master Ready master 14m v1.14.6-k3s.1
k3s-node01 Ready worker 3m11s v1.14.6-k3s.1
k3s-node02 Ready worker 3m58s v1.14.6-k3s.1
$ sudo kubectl get namespaces
NAME STATUS AGE
default Active 16m
kube-node-lease Active 16m
kube-public Active 16m
kube-system Active 16m
$ sudo kubectl get endpoints -n kube-system
NAME ENDPOINTS AGE
kube-dns 10.42.0.2:53,10.42.0.2:53,10.42.0.2:9153 14m
traefik 10.42.0.5:80,10.42.0.5:443 14m
$ sudo kubectl get pods -n kube-system
NAME READY STATUS RESTARTS AGE
coredns-b7464766c-q9frk 1/1 Running 0 15m
helm-install-traefik-8dhpk 0/1 Completed 0 15m
svclb-traefik-9c2j8 2/2 Running 0 4m49s
svclb-traefik-bf9zd 2/2 Running 0 4m2s
svclb-traefik-v2fpx 2/2 Running 0 14m
traefik-5c79b789c5-k589d 1/1 Running 0 14m使用crictl命令来查看正在运行的容器
# Master
$ sudo crictl ps
CONTAINER ID IMAGE CREATED STATE NAME ATTEMPT POD ID
acfafb50852d3 18471c10e6e4b 16 minutes ago Running traefik 0 bf8534452389f
fee5ac7e88f2e 4a065d8dfa588 16 minutes ago Running lb-port-443 0 e7068ff7ab2f2
bbab5b07e5efb 4a065d8dfa588 16 minutes ago Running lb-port-80 0 e7068ff7ab2f2
65c5d1333ea04 2ee68ed074c6e 16 minutes ago Running coredns 0 435c51f4716fc
# Workers
$ sudo crictl ps
CONTAINER ID IMAGE CREATED STATE NAME ATTEMPT POD ID
7ad5c83d6466f 4a065d8dfa588 6 minutes ago Running lb-port-443 0 bf8d9fe57c3f3
c1380eabc0b33 4a065d8dfa588 6 minutes ago Running lb-port-80 0 bf8d9fe57c3f3大功告成啦！如果你需要更高级的配置，请参阅k3s文档：
https://rancher.com/docs/k3s/latest/en/