Kubernetes是一個基于Docker的叢集管理系統，現在也可以在ARM叢集上運作。這 裡介紹基于HypriotOS作業系統的Kubernetes安裝和使用過程（基于樹莓派）。也可以在多種基于ARMbian作業系統 ( https://www.armbian.com/ )的ARM闆上運作（參見 https://www.armbian.com/download/ ）。
1、燒錄作業系統固件 HypriotOS 到 SD cards
硬體上, 至少兩個Raspberry Pis 能夠互相連接配接，并且連接配接到Internet。
首先, 我們需要一個作業系統，下載下傳和燒寫
HypriotOS。最快速的方式是使用
flash tool，如下：
flash --hostname node01 https://github.com/hypriot/image-builder-rpi/releases/download/v1.4.0/hypriotos-rpi-v1.4.0.img.zip
對所有的樹莓派執行上面的操作，然後啟動。
然後, SSH進入Raspberry Pis：
ssh [email protected]
首次啟動密碼為
hypriot
。
2、安裝 Kubernetes
需要root 權限，以root賬戶進入系統，如下：
sudo su -
為了安裝Kubernetes和依賴軟體, 需要執行一些指令。首先, 安裝kubernetes APT 倉庫的key，添加軟體安裝源：
$ curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add - $ echo "deb http://apt.kubernetes.io/ kubernetes-xenial main" > /etc/apt/sources.list.d/kubernetes.list … 安裝
kubeadm
到所有節點：
$ apt-get update && apt-get install -y kubeadm
上面的操作結束後, 初始化 Kubernetes ，在master node 使用：
$ kubeadm init --pod-network-cidr 10.244.0.0/16 這裡的指令，添加
--pod-network-cidr
很重要！因為我們将使用
flannel虛拟網絡，關于 flannel 的注意事項如下，使用之前務必了解：
Some notes about flannel: We picked flannel here because that’s the only available solution for ARM at the moment (this is subject to change in the future though).
flannel can use and is using in this example the Kubernetes API to store metadata about the Pod CIDR allocations, and therefore we need to tell Kubernetes first which subnet we want to use. The subnet we chose here is somehow fixed, because the
flannel configuration file that we’ll use later in this guide predefines the equivalent subnet. Of course, you can adapt both.
如果通過 WIFI連接配接而非有線, 添加
--apiserver-advertise-address=<wifi-ip-address>
作為參數來執行
kubeadm init
，以通過WiFi公布Kubernetes’ API。 還有一些其他的
kubeadm init
參數，你可以去嘗試。
當 Kubernetes 初始化後, 終端視窗顯示如下：
為了啟動叢集, 需要運作 (as a regular user)：
$ sudo cp /etc/kubernetes/admin.conf $HOME/ $ sudo chown $(id -u):$(id -g) $HOME/admin.conf $ export KUBECONFIG=$HOME/admin.conf 下一步, 如上面的輸出所說明, 通過
kubeadm join
指令添加叢集的節點。如（在節點機上執行）：
$ kubeadm join --token=bb14ca.e8bbbedf40c58788 192.168.0.34 幾秒鐘後，你将在 master node上看得見所有的節點，通過執行下面的指令：
$ kubectl get nodes 終端顯示的資訊如下：
最後, 我們需要設定flannel v0.7.1 ，作為Pod network driver. 不要使用
v0.8.0，因為有一個已知的
bug，将會引起
CrashLoopBackOff
錯誤。在 master node 執行：
$ curl -sSL https://rawgit.com/coreos/flannel/v0.7.1/Documentation/kube-flannel-rbac.yml | kubectl create -f - $ curl -sSL https://rawgit.com/coreos/flannel/v0.7.1/Documentation/kube-flannel.yml | sed "s/amd64/arm/g" | kubectl create -f - 然後等待 flannel 和其他 cluster-internal Pods 的運作
Running
，檢視運作情況：
$ kubectl get po --all-namespaces 很好，看起來都在
Running
:
現在Kubernetes已經設定成功! 下一步, 我們在叢集上來實際啟動一個服務。
3、測試安裝是否成功
啟動一個簡單的服務，驗證下叢集是否運作正常，如下：
$ kubectl run hypriot --image=hypriot/rpi-busybox-httpd --replicas=3 --port=80 該指令啟動名為 hypriot的服務，鏡像來自于 hypriot/rpi-busybox-httpd ，端口為 80。該服務的副本設為3，将啟動3個容器執行個體。
下一步，暴露建立的部署後的Pods為穩定的name 和 IP的服務：
$ kubectl expose deployment hypriot --port 80 好了! 現在檢查想要的容器是否啟動和運作：
$ kubectl get endpoints hypriot 将看到三個endpoints (= containers) like this:
使用curl 檢查服務service是否已經起來：
服務響應傳回的HTML如上，很好！下一步，我們将從叢集外部來通路這個服務。
4、從外面通路服務
我們将使用 Ingress Controller示範例程，來管理外部的輸入請求，實作服務的通路。以及，使用
Traefik來進行負載均衡。如果希望倆節 Ingress 和 Traefik的更多内容，建議閱讀下面的内容：
In contrast to Docker Swarm, Kubernetes itself does not provide an option to define a specific port that you can use to access a service. According to Lucas this is an important design decision; routing of incoming requests should be handled by a third party, such as a load balancer or a webserver, but not by the core product. The core Kubernetes should be lean and extensible, and encourage others to build tools on top of it for their specific needs.
Regarding load balancers in front of a cluster, there is
the Ingress API object and some sample Ingress Controllers . Ingress is a built-in way of exposing Services to the outside world via an Ingress Controller that anyone can build. An Ingress rule defines how traffic should flow from the node the Ingress controller runs on to services inside of the cluster.
首先，部署traefik作為負載均衡器：
$ kubectl apply -f https://raw.githubusercontent.com/hypriot/rpi-traefik/master/traefik-k8s-example.yaml Label the node you want to be the load balancer. Then the Traefik Ingress Controller will land on the node you specified. Run:
$ kubectl label node <load balancer-node> nginx-controller=traefik Lastly, create an Ingress object that makes Traefik load balance traffic on port
80
to the
hypriot
service:
$ cat > hypriot-ingress.yaml <<EOF
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: hypriot
spec:
rules:
- http:
paths:
- path: /
backend:
serviceName: hypriot
servicePort: 80
EOF
$ kubectl apply -f hypriot-ingress.yaml Visit the loadbalancing node’s IP address in your browser and you should see a nice web page:
If you don’t see a website there yet, run:
$ kubectl get pods … and make sure all hypriot Pods are in the
Running
state.
Wait until you see that all Pods are running, and a nice Hypriot website should appear!
5、重置 cluster
If you wanna reset the whole cluster to the state after a fresh install, just run this on each node:
$ kubeadm reset In addition, it is recommended to delete some additional files
as it is mentioned here.
6、可選: 部署Kubernetes資訊面闆
The dashboard is a wonderful interface to visualize the state of the cluster. Start it with:
$ kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/master/src/deploy/recommended/kubernetes-dashboard-arm.yaml
Edit the kubernetes-dashboard service to use
type: ClusterIP
to
type: NodePort
, see
Accessing Kubernetes Dashboardfor more details.
$ kubectl -n kube-system edit service kubernetes-dashboard The following command provides the port that the dashboard is exposed at on every node with the NodePort function of Services, which is another way to expose your Services to the outside of your cluster:
$ kubectl -n kube-system get service kubernetes-dashboard -o template --template="{{ (index .spec.ports 0).nodePort }}" | xargs echo Then you can checkout the dashboard on any node’s IP address on that port! Make sure to use
https
when accessing the dashboard, for example if running on port
31657
access it at
https://node:31657
Newer versions of the Kubernetes Dashboard require either a
Kubeconfig
or
Token
to view information on the dashboard.
Bearer tokensare recommended to setup proper permissions for a user, but to test the
replicaset-controller-token
Token may be used to test.
kubectl -n kube-system describe secret `kubectl -n kube-system get secret | grep replicaset-controller-token | awk '{print $1}'` | grep token: | awk '{print $2}' 7、繼續 follow-up?
It was our goal to show that Kubernetes indeed works well on ARM (and ARM 64-bit!). For more examples including the AMD64 platform, check out the
official kubeadm documentationWe might follow-up this blog post with a more in-depth post about the current and planned state of Kubernetes officially on ARM and more, so stay tuned and tell Lucas if that’s something you’re interested in reading.
As always, use the comments below to give us feedback and share this post on Twitter, Google or Facebook.
本文轉自開源中國-
Kubernetes on ARM，基于HypriotOS