1款开源工具，实现自动化升级K3S集群！

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   VERSION
kube-node-c155     Ready    <none>   25h   v1.16.3-k3s.2
kube-node-2404     Ready    <none>   25h   v1.16.3-k3s.2
kube-master-303d   Ready    master   25h   v1.16.3-k3s.2

现在，我们部署CRD：

kind: Namespace
metadata:
  name: system-upgrade
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: system-upgrade
  namespace: system-upgrade
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name:  system-upgrade
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: system-upgrade
  namespace: system-upgrade
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: default-controller-env
  namespace: system-upgrade
data:
  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/v1
kind: Deployment
metadata:
  name: system-upgrade-controller
  namespace: system-upgrade
spec:
  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 tag
curl -s "https://api.github.com/repos/rancher/system-upgrade-controller/releases/latest" | awk -F '"' '/tag_name/{print $4}'
v0.6.2

# Apply the controller manifest
kubectl apply -f https://raw.githubusercontent.com/rancher/system-upgrade-controller/v0.6.2/manifests/system-upgrade-controller.yaml

namespace/system-upgrade created
serviceaccount/system-upgrade created
clusterrolebinding.rbac.authorization.k8s.io/system-upgrade created
configmap/default-controller-env created
deployment.apps/system-upgrade-controller created

# Verify everything is running
kubectl get all -n system-upgrade

NAME                                             READY   STATUS    RESTARTS   AGE
pod/system-upgrade-controller-7fff98589f-blcxs   1/1     Running   0          5m26s

NAME                                        READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/system-upgrade-controller   1/1     1            1           5m28s

NAME                                                   DESIRED   CURRENT   READY   AGE
replicaset.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/v1
kind: Plan
metadata:
  name: k3s-server
  namespace: system-upgrade
  labels:
    k3s-upgrade: server
spec:
  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/v1
kind: Plan
metadata:
  name: k3s-agent
  namespace: system-upgrade
  labels:
    k3s-upgrade: agent
spec:
  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 manifest
kubectl apply -f https://raw.githubusercontent.com/rancher/system-upgrade-controller/master/examples/k3s-upgrade.yaml
plan.upgrade.cattle.io/k3s-server created
plan.upgrade.cattle.io/k3s-agent created

# We see that the jobs have started
kubectl get jobs -n system-upgrade
NAME                                                              COMPLETIONS   DURATION   AGE
apply-k3s-server-on-kube-master-303d-with-9efdeac5f6ede78-125aa   0/1           40s        40s
apply-k3s-agent-on-kube-node-2404-with-9efdeac5f6ede78917-07df3   0/1           39s        39s
apply-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` node
kubectl get nodes
NAME               STATUS                     ROLES    AGE   VERSION
kube-node-2404     Ready,SchedulingDisabled   <none>   26h   v1.16.3-k3s.2
kube-node-c155     Ready,SchedulingDisabled   <none>   26h   v1.16.3-k3s.2
kube-master-303d   Ready                      master   26h   v1.17.4+k3s1

# In a few minutes all nodes get upgraded to latest version as per the plan
kubectl get nodes
NAME               STATUS   ROLES    AGE   VERSION
kube-node-2404     Ready    <none>   26h   v1.17.4+k3s1
kube-node-c155     Ready    <none>   26h   v1.17.4+k3s1
kube-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