Kubernetes 部署手册v1.12.2(10)

  1. 1. 06-2.部署高可用 kube-controller-manager 集群
    1. 1.1. 创建 kube-controller-manager 证书和私钥
    2. 1.2. 创建和分发 kubeconfig 文件
    3. 1.3. 创建和分发 kube-controller-manager systemd unit 文件
    4. 1.4. kube-controller-manager 的权限
    5. 1.5. 启动 kube-controller-manager 服务
    6. 1.6. 检查服务运行状态
    7. 1.7. 查看输出的 metric
    8. 1.8. 测试 kube-controller-manager 集群的高可用
    9. 1.9. 查看当前的 leader
    10. 1.10. 参考

#Kubernetes部署手册v1.12.2(10)

06-2.部署高可用 kube-controller-manager 集群

本文档介绍部署高可用 kube-controller-manager 集群的步骤。

该集群包含 3 个节点,启动后将通过竞争选举机制产生一个 leader 节点,其它节点为阻塞状态。当 leader 节点不可用后,剩余节点将再次进行选举产生新的 leader 节点,从而保证服务的可用性。

为保证通信安全,本文档先生成 x509 证书和私钥,kube-controller-manager 在如下两种情况下使用该证书:

  1. 与 kube-apiserver 的安全端口通信时;
  2. 安全端口(https,10252) 输出 prometheus 格式的 metrics;

创建 kube-controller-manager 证书和私钥

创建证书签名请求:

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cd /opt/k8s/work
cat > kube-controller-manager-csr.json <<EOF
{
"CN": "system:kube-controller-manager",
"key": {
"algo": "rsa",
"size": 2048
},
"hosts": [
"127.0.0.1",
"10.12.11.4",
"10.12.11.5",
"10.12.11.6"
],
"names": [
{
"C": "CN",
"ST": "BeiJing",
"L": "BeiJing",
"O": "system:kube-controller-manager",
"OU": "Lenovo"
}
]
}
EOF
  • hosts 列表包含所有 kube-controller-manager 节点 IP;
  • CN 为 system:kube-controller-manager、O 为 system:kube-controller-manager,kubernetes 内置的 ClusterRoleBindings system:kube-controller-manager 赋予 kube-controller-manager 工作所需的权限。

生成证书和私钥:

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cd /opt/k8s/work
cfssl gencert -ca=/opt/k8s/work/ca.pem \
-ca-key=/opt/k8s/work/ca-key.pem \
-config=/opt/k8s/work/ca-config.json \
-profile=kubernetes kube-controller-manager-csr.json | cfssljson -bare kube-controller-manager
ls kube-controller-manager*pem

将生成的证书和私钥分发到所有 master 节点:

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cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
echo ">>> ${node_ip}"
scp kube-controller-manager*.pem k8s@${node_ip}:/etc/kubernetes/cert/
done

创建和分发 kubeconfig 文件

kubeconfig 文件包含访问 apiserver 的所有信息,如 apiserver 地址、CA 证书和自身使用的证书;

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cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
kubectl config set-cluster kubernetes \
--certificate-authority=/opt/k8s/work/ca.pem \
--embed-certs=true \
--server=${KUBE_APISERVER} \
--kubeconfig=kube-controller-manager.kubeconfig

kubectl config set-credentials system:kube-controller-manager \
--client-certificate=kube-controller-manager.pem \
--client-key=kube-controller-manager-key.pem \
--embed-certs=true \
--kubeconfig=kube-controller-manager.kubeconfig

kubectl config set-context system:kube-controller-manager \
--cluster=kubernetes \
--user=system:kube-controller-manager \
--kubeconfig=kube-controller-manager.kubeconfig

kubectl config use-context system:kube-controller-manager --kubeconfig=kube-controller-manager.kubeconfig

分发 kubeconfig 到所有 master 节点:

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cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
echo ">>> ${node_ip}"
scp kube-controller-manager.kubeconfig k8s@${node_ip}:/etc/kubernetes/
done

创建和分发 kube-controller-manager systemd unit 文件

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cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
cat > kube-controller-manager.service <<EOF
[Unit]
Description=Kubernetes Controller Manager
Documentation=https://github.com/GoogleCloudPlatform/kubernetes

[Service]
WorkingDirectory=/mnt/disk0/k8s/kube-controller-manager
ExecStart=/opt/k8s/bin/kube-controller-manager \\
--port=0 \\
--secure-port=10252 \\
--bind-address=127.0.0.1 \\
--kubeconfig=/etc/kubernetes/kube-controller-manager.kubeconfig \\
--service-cluster-ip-range=${SERVICE_CIDR} \\
--cluster-name=kubernetes \\
--cluster-signing-cert-file=/etc/kubernetes/cert/ca.pem \\
--cluster-signing-key-file=/etc/kubernetes/cert/ca-key.pem \\
--experimental-cluster-signing-duration=8760h \\
--root-ca-file=/etc/kubernetes/cert/ca.pem \\
--service-account-private-key-file=/etc/kubernetes/cert/ca-key.pem \\
--leader-elect=true \\
--feature-gates=RotateKubeletServerCertificate=true \\
--controllers=*,bootstrapsigner,tokencleaner \\
--horizontal-pod-autoscaler-use-rest-clients=true \\
--horizontal-pod-autoscaler-sync-period=10s \\
--tls-cert-file=/etc/kubernetes/cert/kube-controller-manager.pem \\
--tls-private-key-file=/etc/kubernetes/cert/kube-controller-manager-key.pem \\
--use-service-account-credentials=true \\
--logtostderr=false \\
--alsologtostderr=true \\
--log-dir=/mnt/disk0/k8s/kube-controller-manager/log \\
--v=2
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF
  • --port=0:关闭监听 http /metrics 的请求,同时 --address 参数无效,--bind-address 参数有效;
  • --secure-port=10252--bind-address=0.0.0.0: 在所有网络接口监听 10252 端口的 https /metrics 请求;
  • --kubeconfig:指定 kubeconfig 文件路径,kube-controller-manager 使用它连接和验证 kube-apiserver;
  • --cluster-signing-*-file:签名 TLS Bootstrap 创建的证书;
  • --experimental-cluster-signing-duration:指定 TLS Bootstrap 证书的有效期;
  • --root-ca-file:放置到容器 ServiceAccount 中的 CA 证书,用来对 kube-apiserver 的证书进行校验;
  • --service-account-private-key-file:签名 ServiceAccount 中 Token 的私钥文件,必须和 kube-apiserver 的 --service-account-key-file 指定的公钥文件配对使用;
  • --service-cluster-ip-range :指定 Service Cluster IP 网段,必须和 kube-apiserver 中的同名参数一致;
  • --leader-elect=true:集群运行模式,启用选举功能;被选为 leader 的节点负责处理工作,其它节点为阻塞状态;
  • --feature-gates=RotateKubeletServerCertificate=true:开启 kublet server 证书的自动更新特性;
  • --controllers=*,bootstrapsigner,tokencleaner:启用的控制器列表,tokencleaner 用于自动清理过期的 Bootstrap token;
  • --horizontal-pod-autoscaler-*:custom metrics 相关参数,支持 autoscaling/v2alpha1;
  • --tls-cert-file--tls-private-key-file:使用 https 输出 metrics 时使用的 Server 证书和秘钥;
  • --use-service-account-credentials=true: kube-controller-manager 中各 controller 使用 serviceaccount 访问 kube-apiserver;

kube-controller-manager 不对请求 https metrics 的 Client 证书进行校验,故不需要指定 --tls-ca-file 参数,而且该参数已被淘汰。

分发 systemd unit 文件到所有 master 节点:

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cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
echo ">>> ${node_ip}"
scp kube-controller-manager.service k8s@${node_ip}:/etc/systemd/system/
done

kube-controller-manager 的权限

ClusteRole: system:kube-controller-manager 的权限很小,只能创建 secret、serviceaccount 等资源对象,各 controller 的权限分散到 ClusterRole system:controller:XXX 中。

需要在 kube-controller-manager 的启动参数中添加 --use-service-account-credentials=true 参数,这样 main controller 会为各 controller 创建对应的 ServiceAccount XXX-controller。

内置的 ClusterRoleBinding system:controller:XXX 将赋予各 XXX-controller ServiceAccount 对应的 ClusterRole system:controller:XXX 权限。

启动 kube-controller-manager 服务

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source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
echo ">>> ${node_ip}"
ssh k8s@${node_ip} "sudo mkdir -p /mnt/disk0/k8s/kube-controller-manager/log"
ssh k8s@${node_ip} "sudo systemctl daemon-reload && sudo systemctl enable kube-controller-manager && sudo systemctl restart kube-controller-manager"
done
  • 必须先创建日志目录;

检查服务运行状态

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source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
echo ">>> ${node_ip}"
ssh k8s@${node_ip} "sudo systemctl status kube-controller-manager|grep Active"
done

确保状态为 active (running),否则查看日志,确认原因:

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$ journalctl -u kube-controller-manager

查看输出的 metric

注意:以下命令在 kube-controller-manager 节点上执行。

kube-controller-manager 监听 10252 端口,接收 https 请求:

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$ sudo netstat -lnpt|grep kube-controll
tcp 0 0 127.0.0.1:10252 0.0.0.0:* LISTEN 18377/kube-controll
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$ curl -s --cacert /etc/kubernetes/cert/ca.pem https://127.0.0.1:10252/metrics |head
# HELP ClusterRoleAggregator_adds Total number of adds handled by workqueue: ClusterRoleAggregator
# TYPE ClusterRoleAggregator_adds counter
ClusterRoleAggregator_adds 3
# HELP ClusterRoleAggregator_depth Current depth of workqueue: ClusterRoleAggregator
# TYPE ClusterRoleAggregator_depth gauge
ClusterRoleAggregator_depth 0
# HELP ClusterRoleAggregator_queue_latency How long an item stays in workqueueClusterRoleAggregator before being requested.
# TYPE ClusterRoleAggregator_queue_latency summary
ClusterRoleAggregator_queue_latency{quantile="0.5"} 57018
ClusterRoleAggregator_queue_latency{quantile="0.9"} 57268
  • curl –cacert CA 证书用来验证 kube-controller-manager https server 证书;

测试 kube-controller-manager 集群的高可用

停掉一个或两个节点的 kube-controller-manager 服务,观察其它节点的日志,看是否获取了 leader 权限。

查看当前的 leader

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$ kubectl get endpoints kube-controller-manager --namespace=kube-system  -o yaml
apiVersion: v1
kind: Endpoints
metadata:
annotations:
control-plane.alpha.kubernetes.io/leader: '{"holderIdentity":"zb-v-cld-k8sm-02_084534e2-6cc4-11e8-a418-5254001f5b65","leaseDurationSeconds":15,"acquireTime":"2018-11-10T15:40:33Z","renewTime":"2018-11-10T16:19:08Z","leaderTransitions":12}'
creationTimestamp: 2018-11-10T13:59:42Z
name: kube-controller-manager
namespace: kube-system
resourceVersion: "4540"
selfLink: /api/v1/namespaces/kube-system/endpoints/kube-controller-manager
uid: 862cc048-6cb6-11e8-96fa-525400ba84c6

可见,当前的 leader 为 zb-v-cld-k8sm-02 节点。

参考

  1. 关于 controller 权限和 use-service-account-credentials 参数:https://github.com/kubernetes/kubernetes/issues/48208
  2. kublet 认证和授权:https://kubernetes.io/docs/admin/kubelet-authentication-authorization/#kubelet-authorization