K3s - 轻量级 Kubernetes

http://docs.rancher.cn/docs/k3s/_index

https://github.com/k3s-io/k3s/releases
https://github.com/k3s-io/k3s-ansible

image.png

https://docs.rancher.cn/docs/k3s/_index

为什么叫 K3s?

我们希望安装的 Kubernetes 在内存占用方面只是一半的大小。Kubernetes 是一个 10 个字母的单词，简写为 K8s。所以，有 Kubernetes 一半大的东西就是一个 5 个字母的单词，简写为 K3s。K3s 没有全称，也没有官方的发音

K3s - 图2

K3s - 图3

image.png

K3s - 图5
https://www.cnblogs.com/k3s2019/p/13646252.html

https://rancher2.docs.rancher.cn/docs/k3s/_index

K3s 是一个完全符合 Kubernetes 的发行版，有以下增强功能。

  • 打包为单个二进制文件。
  • 基于 sqlite3 的轻量级存储后端作为默认存储机制。 etcd3，MySQL，Postgres 仍然可用。
  • 封装在简单的启动程序中，该启动程序处理很多复杂的 TLS 和选项。
  • 默认情况下是安全的，对轻量级环境有合理的默认值。
  • 添加了简单但功能强大的“batteries-included”功能，例如：本地存储提供程序，服务负载均衡器，Helm controller 和 Traefik ingress controller。
  • 所有 Kubernetes control-plane 组件的操作都封装在单个二进制文件和进程中。这使 K3s 可以自动化和管理复杂的集群操作，例如分发证书。
  • 外部依赖性已最小化（仅需要现代内核和 cgroup 挂载）。 K3s 软件包需要依赖项，包括：
    • containerd
    • Flannel
    • CoreDNS
    • CNI
    • 主机实用程序 (iptables, socat, etc)
    • Ingress controller (traefik)
    • 嵌入式 service loadbalancer
    • 嵌入式 network policy controller

面向DevOps的K3s托管服务.pdf

Master

  1. curl -sfL http://rancher-mirror.cnrancher.com/k3s/k3s-install.sh | INSTALL_K3S_MIRROR=cn  INSTALL_K3S_EXEC="--docker" sh -s - server

Node

  1. curl -sfL http://rancher-mirror.cnrancher.com/k3s/k3s-install.sh | INSTALL_K3S_MIRROR=cn INSTALL_K3S_EXEC="--docker" K3S_URL=https://192.168.15.252:6443 K3S_TOKEN=K10bb35019b1669197e06f97b6c14bb3b3c7c7076cd20afe1f550d6793d02b9eed8::server:9599c8b3ffbbd38b7721207183cd6a62 sh -

安装

  1. [root@rancher-server ~]# curl -sfL http://rancher-mirror.cnrancher.com/k3s/k3s-install.sh | INSTALL_K3S_MIRROR=cn sh -
  2. [INFO]  Finding release for channel stable
  3. [INFO]  Using v1.20.5+k3s1 as release
  4. [INFO]  Downloading hash http://rancher-mirror.cnrancher.com/k3s/v1.20.5-k3s1/sha256sum-amd64.txt
  5. [INFO]  Downloading binary http://rancher-mirror.cnrancher.com/k3s/v1.20.5-k3s1/k3s
  6. [INFO]  Verifying binary download
  7. [INFO]  Installing k3s to /usr/local/bin/k3s
  8. Loaded plugins: fastestmirror, langpacks
  9. Loading mirror speeds from cached hostfile
  10.  * base: mirrors.aliyun.com
  11.  * extras: mirrors.aliyun.com
  12.  * updates: mirrors.aliyun.com
  13. base                                                                                                                      | 3.6 kB  00:00:00
  14. docker-ce-stable                                                                                                          | 3.5 kB  00:00:00
  15. extras                                                                                                                    | 2.9 kB  00:00:00
  16. updates                                                                                                                   | 2.9 kB  00:00:00
  17. (1/2): extras/7/x86_64/primary_db                                                                                         | 232 kB  00:00:00
  18. (2/2): updates/7/x86_64/primary_db                                                                                        | 7.1 MB  00:00:01
  19. Package yum-utils-1.1.31-54.el7_8.noarch already installed and latest version
  20. Nothing to do
  21. Loaded plugins: fastestmirror, langpacks
  22. Loaded plugins: fastestmirror, langpacks
  23. Loading mirror speeds from cached hostfile
  24.  * base: mirrors.aliyun.com
  25.  * extras: mirrors.aliyun.com
  26.  * updates: mirrors.aliyun.com
  27. rancher-k3s-common-stable                                                                                                 | 2.9 kB  00:00:00
  28. rancher-k3s-common-stable/primary_db                                                                                      | 2.2 kB  00:00:01
  29. Resolving Dependencies
  30. --> Running transaction check
  31. ---> Package k3s-selinux.noarch 0:0.3-0.el7 will be installed
  32. --> Finished Dependency Resolution
  34. Dependencies Resolved
  36. =================================================================================================================================================
  37.  Package                         Arch                       Version                          Repository                                     Size
  38. =================================================================================================================================================
  39. Installing:
  40.  k3s-selinux                     noarch                     0.3-0.el7                        rancher-k3s-common-stable                      14 k
  42. Transaction Summary
  43. =================================================================================================================================================
  44. Install  1 Package
  46. Total download size: 14 k
  47. Installed size: 82 k
  48. Downloading packages:
  49. warning: /var/cache/yum/x86_64/7/rancher-k3s-common-stable/packages/k3s-selinux-0.3-0.el7.noarch.rpm: Header V4 RSA/SHA1 Signature, key ID e257814a: NOKEY
  50. Public key for k3s-selinux-0.3-0.el7.noarch.rpm is not installed
  51. k3s-selinux-0.3-0.el7.noarch.rpm                                                                                          |  14 kB  00:00:01
  52. Retrieving key from https://rpm.rancher.io/public.key
  53. Importing GPG key 0xE257814A:
  54.  Userid     : "Rancher (CI) <ci@rancher.com>"
  55.  Fingerprint: c8cf f216 4551 26e9 b9c9 18be 925e a29a e257 814a
  56.  From       : https://rpm.rancher.io/public.key
  57. Running transaction check
  58. Running transaction test
  59. Transaction test succeeded
  60. Running transaction
  61.   Installing : k3s-selinux-0.3-0.el7.noarch                                                                                                  1/1
  62.   Verifying  : k3s-selinux-0.3-0.el7.noarch                                                                                                  1/1
  64. Installed:
  65.   k3s-selinux.noarch 0:0.3-0.el7
  67. Complete!
  68. [INFO]  Creating /usr/local/bin/kubectl symlink to k3s
  69. [INFO]  Creating /usr/local/bin/crictl symlink to k3s
  70. [INFO]  Skipping /usr/local/bin/ctr symlink to k3s, command exists in PATH at /usr/bin/ctr
  71. [INFO]  Creating killall script /usr/local/bin/k3s-killall.sh
  72. [INFO]  Creating uninstall script /usr/local/bin/k3s-uninstall.sh
  73. [INFO]  env: Creating environment file /etc/systemd/system/k3s.service.env
  74. [INFO]  systemd: Creating service file /etc/systemd/system/k3s.service
  75. [INFO]  systemd: Enabling k3s unit
  76. [INFO]  systemd: Starting k3s
  77. [root@rancher-server ~]# kubectl get node
  78. NAME             STATUS     ROLES                  AGE   VERSION
  79. rancher-server   NotReady   control-plane,master   9s    v1.20.5+k3s1
  80. [root@rancher-server ~]#
  82. [root@rancher-server ~]# kubectl get cs
  83. Warning: v1 ComponentStatus is deprecated in v1.19+
  84. NAME                 STATUS    MESSAGE   ERROR
  85. scheduler            Healthy   ok
  86. controller-manager   Healthy   ok
  87. [root@rancher-server ~]#
  88. [root@rancher-server ~]# kubectl get node
  89. NAME             STATUS   ROLES                  AGE   VERSION
  90. rancher-server   Ready    control-plane,master   43s   v1.20.5+k3s1
  1. [root@rancher-server ~]# kubectl -n kube-system get pod
  2. NAME                                      READY   STATUS      RESTARTS   AGE
  3. local-path-provisioner-5ff76fc89d-7ln66   1/1     Running     0          2m50s
  4. metrics-server-86cbb8457f-m78sj           1/1     Running     0          2m50s
  5. coredns-854c77959c-q2ffz                  1/1     Running     0          2m50s
  6. helm-install-traefik-8kblc                0/1     Completed   0          2m50s
  7. svclb-traefik-pb78l                       2/2     Running     0          111s
  8. traefik-6f9cbd9bd4-bcx6c                  1/1     Running     0          111s
  9. [root@rancher-server ~]#
  1. [root@rancher-server ~]# kubectl -n kube-system get all
  2. NAME                                          READY   STATUS      RESTARTS   AGE
  3. pod/local-path-provisioner-5ff76fc89d-7ln66   1/1     Running     0          4m5s
  4. pod/metrics-server-86cbb8457f-m78sj           1/1     Running     0          4m5s
  5. pod/coredns-854c77959c-q2ffz                  1/1     Running     0          4m5s
  6. pod/helm-install-traefik-8kblc                0/1     Completed   0          4m5s
  7. pod/svclb-traefik-pb78l                       2/2     Running     0          3m6s
  8. pod/traefik-6f9cbd9bd4-bcx6c                  1/1     Running     0          3m6s
  10. NAME                         TYPE           CLUSTER-IP      EXTERNAL-IP    PORT(S)                      AGE
  11. service/kube-dns             ClusterIP      10.43.0.10      <none>         53/UDP,53/TCP,9153/TCP       4m19s
  12. service/metrics-server       ClusterIP      10.43.112.206   <none>         443/TCP                      4m18s
  13. service/traefik-prometheus   ClusterIP      10.43.219.182   <none>         9100/TCP                     3m6s
  14. service/traefik              LoadBalancer   10.43.153.111   192.168.6.99   80:32445/TCP,443:30528/TCP   3m6s
  16. NAME                           DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGE
  17. daemonset.apps/svclb-traefik   1         1         1       1            1           <none>          3m6s
  19. NAME                                     READY   UP-TO-DATE   AVAILABLE   AGE
  20. deployment.apps/local-path-provisioner   1/1     1            1           4m19s
  21. deployment.apps/metrics-server           1/1     1            1           4m18s
  22. deployment.apps/coredns                  1/1     1            1           4m19s
  23. deployment.apps/traefik                  1/1     1            1           3m6s
  25. NAME                                                DESIRED   CURRENT   READY   AGE
  26. replicaset.apps/local-path-provisioner-5ff76fc89d   1         1         1       4m5s
  27. replicaset.apps/metrics-server-86cbb8457f           1         1         1       4m5s
  28. replicaset.apps/coredns-854c77959c                  1         1         1       4m5s
  29. replicaset.apps/traefik-6f9cbd9bd4                  1         1         1       3m6s
  31. NAME                             COMPLETIONS   DURATION   AGE
  32. job.batch/helm-install-traefik   1/1           60s        4m16s
  33. [root@rancher-server ~]# kubectl get ns
  34. NAME              STATUS   AGE
  35. default           Active   4m38s
  36. kube-system       Active   4m38s
  37. kube-public       Active   4m38s
  38. kube-node-lease   Active   4m38s
  39. [root@rancher-server ~]#

卸载

  1. 卸载K3S
  3. #服务器
  5. /usr/local/bin/k3s-uninstall.sh
  7. #工作节点
  9. /usr/local/bin/k3s-agent-uninstall.sh