1款开源工具，实现自动化升级K3S集群！

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· 2020-11-28

即便你的集群能够平稳运行，Kubernetes升级依旧是一项艰难的任务。由于每3个月Kubernetes会发布一个新版本，所以升级是十分必要的。如果一年内你不升级你的Kubernetes集群，你就会落后许多。Rancher致力于解决开发运维人员的痛点，于是创建了新的开源项目System Upgrade Controller可以帮助开发人员平滑升级。

System Upgrade Controller引入了一个新的Kubernetes自定义资源定义（CRD），称为Plan。现在Plan是处理升级进程的主要组件。以下是从git repo获取的架构图：

使用System Upgrade Controller

自动升级K3s

升级K3s Kubernetes集群有两个主要要求：

CRD安装
创建Plan

首先，让我们检查当前正在运行的K3s集群版本。

运行以下命令，即可快速安装：

#For master install:curl -sfL https://get.k3s.io | INSTALL_K3S_VERSION=v1.16.3-k3s.2 sh
#For joining nodes:K3S_TOKEN is created at /var/lib/rancher/k3s/server/node-token on the server.For adding nodes, K3S_URL and K3S_TOKEN needs to be passed:
curl -sfL https://get.k3s.io | K3S_URL=https://myserver:6443 K3S_TOKEN=XXX sh -

KUBECONFIG file is create at /etc/rancher/k3s/k3s.yaml location

kubectl get nodes
NAME               STATUS   ROLES    AGE   VERSIONkube-node-c155     Ready    <none>   25h   v1.16.3-k3s.2kube-node-2404     Ready    <none>   25h   v1.16.3-k3s.2kube-master-303d   Ready    master   25h   v1.16.3-k3s.2

现在，我们部署CRD：

apiVersion: v1kind: Namespacemetadata:  name: system-upgrade---apiVersion: v1kind: ServiceAccountmetadata:  name: system-upgrade  namespace: system-upgrade---apiVersion: rbac.authorization.k8s.io/v1kind: ClusterRoleBindingmetadata:  name:  system-upgraderoleRef:  apiGroup: rbac.authorization.k8s.io  kind: ClusterRole  name: cluster-adminsubjects:- kind: ServiceAccount  name: system-upgrade  namespace: system-upgrade---apiVersion: v1kind: ConfigMapmetadata:  name: default-controller-env  namespace: system-upgradedata:  SYSTEM_UPGRADE_CONTROLLER_DEBUG: "false"  SYSTEM_UPGRADE_CONTROLLER_THREADS: "2"  SYSTEM_UPGRADE_JOB_ACTIVE_DEADLINE_SECONDS: "900"  SYSTEM_UPGRADE_JOB_BACKOFF_LIMIT: "99"  SYSTEM_UPGRADE_JOB_IMAGE_PULL_POLICY: "Always"  SYSTEM_UPGRADE_JOB_KUBECTL_IMAGE: "rancher/kubectl:v1.18.3"  SYSTEM_UPGRADE_JOB_PRIVILEGED: "true"  SYSTEM_UPGRADE_JOB_TTL_SECONDS_AFTER_FINISH: "900"  SYSTEM_UPGRADE_PLAN_POLLING_INTERVAL: "15m"---apiVersion: apps/v1kind: Deploymentmetadata:  name: system-upgrade-controller  namespace: system-upgradespec:  selector:    matchLabels:      upgrade.cattle.io/controller: system-upgrade-controller  template:    metadata:      labels:        upgrade.cattle.io/controller: system-upgrade-controller # necessary to avoid drain    spec:      affinity:        nodeAffinity:          requiredDuringSchedulingIgnoredDuringExecution:            nodeSelectorTerms:              - matchExpressions:                  - {key: "node-role.kubernetes.io/master", operator: In, values: ["true"]}      serviceAccountName: system-upgrade      tolerations:        - key: "CriticalAddonsOnly"          operator: "Exists"        - key: "node-role.kubernetes.io/master"          operator: "Exists"          effect: "NoSchedule"      containers:        - name: system-upgrade-controller          image: rancher/system-upgrade-controller:v0.5.0          imagePullPolicy: IfNotPresent          envFrom:            - configMapRef:                name: default-controller-env          env:            - name: SYSTEM_UPGRADE_CONTROLLER_NAME              valueFrom:                fieldRef:                  fieldPath: metadata.labels['upgrade.cattle.io/controller']            - name: SYSTEM_UPGRADE_CONTROLLER_NAMESPACE              valueFrom:                fieldRef:                  fieldPath: metadata.namespace          volumeMounts:            - name: etc-ssl              mountPath: /etc/ssl            - name: tmp              mountPath: /tmp      volumes:        - name: etc-ssl          hostPath:            path: /etc/ssl            type: Directory        - name: tmp          emptyDir: {}

将上面的yaml分解，它将创建以下组件：

system-upgrade命名空间
system-upgrade服务账户
system-upgrade ClusterRoleBinding
用于设置容器中环境变量的config map
实际部署

现在，我们来部署yaml：

#Get the Lateest release tagcurl -s "https://api.github.com/repos/rancher/system-upgrade-controller/releases/latest" | awk -F '"' '/tag_name/{print $4}'v0.6.2
# Apply the controller manifestkubectl apply -f https://raw.githubusercontent.com/rancher/system-upgrade-controller/v0.6.2/manifests/system-upgrade-controller.yaml
namespace/system-upgrade createdserviceaccount/system-upgrade createdclusterrolebinding.rbac.authorization.k8s.io/system-upgrade createdconfigmap/default-controller-env createddeployment.apps/system-upgrade-controller created
# Verify everything is runningkubectl get all -n system-upgrade
NAME                                             READY   STATUS    RESTARTS   AGEpod/system-upgrade-controller-7fff98589f-blcxs   1/1     Running   0          5m26s
NAME                                        READY   UP-TO-DATE   AVAILABLE   AGEdeployment.apps/system-upgrade-controller   1/1     1            1           5m28s
NAME                                                   DESIRED   CURRENT   READY   AGEreplicaset.apps/system-upgrade-controller-7fff98589f   1         1         1       5m28s

创建一个K3s升级Plan

现在，是时候创建一个升级Plan。我们将使用在Git repo示例文件夹中提到的示例Plan。

---apiVersion: upgrade.cattle.io/v1kind: Planmetadata:  name: k3s-server  namespace: system-upgrade  labels:    k3s-upgrade: serverspec:  concurrency: 1  version: v1.17.4+k3s1  nodeSelector:    matchExpressions:      - {key: k3s-upgrade, operator: Exists}      - {key: k3s-upgrade, operator: NotIn, values: ["disabled", "false"]}      - {key: k3s.io/hostname, operator: Exists}      - {key: k3os.io/mode, operator: DoesNotExist}      - {key: node-role.kubernetes.io/master, operator: In, values: ["true"]}  serviceAccountName: system-upgrade  cordon: true#  drain:#    force: true  upgrade:    image: rancher/k3s-upgrade---apiVersion: upgrade.cattle.io/v1kind: Planmetadata:  name: k3s-agent  namespace: system-upgrade  labels:    k3s-upgrade: agentspec:  concurrency: 2  version: v1.17.4+k3s1  nodeSelector:    matchExpressions:      - {key: k3s-upgrade, operator: Exists}      - {key: k3s-upgrade, operator: NotIn, values: ["disabled", "false"]}      - {key: k3s.io/hostname, operator: Exists}      - {key: k3os.io/mode, operator: DoesNotExist}      - {key: node-role.kubernetes.io/master, operator: NotIn, values: ["true"]}  serviceAccountName: system-upgrade  prepare:    # Since v0.5.0-m1 SUC will use the resolved version of the plan for the tag on the prepare container.    # image: rancher/k3s-upgrade:v1.17.4-k3s1    image: rancher/k3s-upgrade    args: ["prepare", "k3s-server"]  drain:    force: true  upgrade:    image: rancher/k3s-upgrade

拆解以上yaml，它将创建：

与表达式匹配的Plan，以了解需要升级的内容。所以在上述例子中，我们有2个plan：k3s-server和k3s-agent。node-role.kubernetes.io/master为true和k3s-upgrade的节点将被server Plan占用。带false的将由client Plan占用。所以标签必须要设置正确。接下来，我们来apply Plan。

#Set the Node Labels
kubectl label node kube-master-303d node-role.kubernetes.io/master=true

# Apply the plan manifestkubectl apply -f https://raw.githubusercontent.com/rancher/system-upgrade-controller/master/examples/k3s-upgrade.yamlplan.upgrade.cattle.io/k3s-server createdplan.upgrade.cattle.io/k3s-agent created
# We see that the jobs have startedkubectl get jobs -n system-upgradeNAME                                                              COMPLETIONS   DURATION   AGEapply-k3s-server-on-kube-master-303d-with-9efdeac5f6ede78-125aa   0/1           40s        40sapply-k3s-agent-on-kube-node-2404-with-9efdeac5f6ede78917-07df3   0/1           39s        39sapply-k3s-agent-on-kube-node-c155-with-9efdeac5f6ede78917-9a585   0/1           39s        39s


# Upgrade in-progress, completed on the `node-role.kubernetes.io/master=true` nodekubectl get nodesNAME               STATUS                     ROLES    AGE   VERSIONkube-node-2404     Ready,SchedulingDisabled   <none>   26h   v1.16.3-k3s.2kube-node-c155     Ready,SchedulingDisabled   <none>   26h   v1.16.3-k3s.2kube-master-303d   Ready                      master   26h   v1.17.4+k3s1
# In a few minutes all nodes get upgraded to latest version as per the plankubectl get nodesNAME               STATUS   ROLES    AGE   VERSIONkube-node-2404     Ready    <none>   26h   v1.17.4+k3s1kube-node-c155     Ready    <none>   26h   v1.17.4+k3s1kube-master-303d   Ready    master   26h   v1.17.4+k3s1

我们的K3s Kubernetes升级完成！极为轻松而且十分顺利。Project可以更新底层操作系统并重启节点。欢迎尝试哟！

Github地址：

https://github.com/rancher/system-upgrade-controller