部署 kube-controller-manager 高可用集群

目录

• 前言
• 创建kube-controller-manager证书和私钥
• 生成证书和私钥
  • 将生成的证书和私钥分发到所有master节点
• 创建和分发kubeconfig文件
  • 分发kubeconfig到所有master节点
• 创建 kube-controller-manager 启动文件
  • 替换启动文件，并分发脚本
  • 启动服务
  • 检查服务端口
• 查看 kube-controller-manager 创建权限
• 通过apiserver查看controller-manager状态

前言

该集群包含三个节点，启动后通过竞争选举机制产生一个leader节点，其他节点为阻塞状态。当leader节点不可用时，阻塞节点将会在此选举产生新的leader，从而保证服务的高可用。为保证通信安全，这里采用x509证书和私钥，kube-controller-manager在与apiserver的安全端口（http 10252）通信使用；

创建kube-controller-manager证书和私钥

创建证书签名请求

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",
        "10.0.20.11",
        "10.0.20.12",
        "10.0.20.13",
        "node01.k8s.com",
        "node02.k8s.com",
        "node03.k8s.com"
    ],
    "names": [
      {
        "C": "CN",
        "ST": "BeiJing",
        "L": "BeiJing",
        "O": "system:kube-controller-manager",
        "OU": "4Paradigm"
      }
    ]
}
EOF

• host列表包含所有的kube-controller-manager节点IP(VIP不需要输入)
• CN和O均为system:kube-controller-manager，kubernetes内置的ClusterRoleBindings system:kube-controller-manager赋予kube-controller-manager工作所需权限

生成证书和私钥

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

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

创建和分发kubeconfig文件

• kube-controller-manager使用kubeconfig文件访问apiserver
• 该文件提供了apiserver地址、嵌入的CA证书和kube-controller-manager证书

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

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

创建 kube-controller-manager 启动文件

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
cat > kube-controller-manager.service.template <<EOF
[Unit]
Description=Kubernetes Controller Manager
Documentation=https://github.com/GoogleCloudPlatform/kubernetes
[Service]
WorkingDirectory=${K8S_DIR}/kube-controller-manager
ExecStart=/opt/k8s/bin/kube-controller-manager \
  --profiling \
  --cluster-name=kubernetes \
  --controllers=*,bootstrapsigner,tokencleaner \
  --kube-api-qps=1000 \
  --kube-api-burst=2000 \
  --leader-elect \
  --use-service-account-credentials\
  --concurrent-service-syncs=2 \
  --bind-address=0.0.0.0 \
  #--secure-port=10252 \
  --tls-cert-file=/etc/kubernetes/cert/kube-controller-manager.pem \
  --tls-private-key-file=/etc/kubernetes/cert/kube-controller-manager-key.pem \
  #--port=0 \
  --authentication-kubeconfig=/etc/kubernetes/kube-controller-manager.kubeconfig \
  --client-ca-file=/etc/kubernetes/cert/ca.pem \
  --requestheader-allowed-names="" \
  --requestheader-client-ca-file=/etc/kubernetes/cert/ca.pem \
  --requestheader-extra-headers-prefix="X-Remote-Extra-" \
  --requestheader-group-headers=X-Remote-Group \
  --requestheader-username-headers=X-Remote-User \
  --authorization-kubeconfig=/etc/kubernetes/kube-controller-manager.kubeconfig \
  --cluster-signing-cert-file=/etc/kubernetes/cert/ca.pem \
  --cluster-signing-key-file=/etc/kubernetes/cert/ca-key.pem \
  --experimental-cluster-signing-duration=876000h \
  --horizontal-pod-autoscaler-sync-period=10s \
  --concurrent-deployment-syncs=10 \
  --concurrent-gc-syncs=30 \
  --node-cidr-mask-size=24 \
  --service-cluster-ip-range=${SERVICE_CIDR} \
  --pod-eviction-timeout=6m \
  --terminated-pod-gc-threshold=10000 \
  --root-ca-file=/etc/kubernetes/cert/ca.pem \
  --service-account-private-key-file=/etc/kubernetes/cert/ca-key.pem \
  --kubeconfig=/etc/kubernetes/kube-controller-manager.kubeconfig \
  --logtostderr=true \
  --v=2
Restart=on-failure
RestartSec=5
[Install]
WantedBy=multi-user.target
EOF

参数解释

• –port=0：关闭监听非安全端口（http），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；
• –authentication-kubeconfig 和 –authorization-kubeconfig：kube-controller-manager 使用它连接 apiserver，对 client 的请求进行认证和授权。kube-controller-manager 不再使用 –tls-ca-file 对请求 https metrics 的 Client 证书进行校验。如果没有配置这两个 kubeconfig 参数，则 client 连接 kube-controller-manager https 端口的请求会被拒绝(提示权限不足)。
• –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；
• –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；

替换启动文件，并分发脚本

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for (( i=0; i < 3; i++ ))
  do
    sed -e "s/##NODE_NAME##/${MASTER_NAMES[i]}/" -e "s/##NODE_IP##/${MASTER_IPS[i]}/" kube-controller-manager.service.template > kube-controller-manager-${MASTER_IPS[i]}.service 
  done
ls kube-controller-manager*.service

分发到所有master节点

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

启动服务

source /opt/k8s/bin/environment.sh
for node_ip in ${MASTER_IPS[@]}
  do
    echo ">>> ${node_ip}"
    ssh root@${node_ip} "mkdir -p ${K8S_DIR}/kube-controller-manager"
    ssh root@${node_ip} "systemctl daemon-reload && systemctl enable kube-controller-manager && systemctl restart kube-controller-manager"
  done

检查运行状态

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

检查服务端口

for node_ip in ${MASTER_IPS[@]}
  do
    echo ">>> ${node_ip}"
    ssh root@${node_ip} "netstat -lnpt | grep kube-controlle"
  done

输出结果

[root@node01 work]# for node_ip in ${MASTER_IPS[@]}
>   do
>     echo ">>> ${node_ip}"
>     ssh root@${node_ip} "netstat -lnpt | grep kube-controlle"
>   done
>>> 10.0.20.11
tcp6       0      0 :::10252                :::*                    LISTEN      6127/kube-controlle 
tcp6       0      0 :::10257                :::*                    LISTEN      6127/kube-controlle 
>>> 10.0.20.12
tcp6       0      0 :::10252                :::*                    LISTEN      2914/kube-controlle 
tcp6       0      0 :::10257                :::*                    LISTEN      2914/kube-controlle 
>>> 10.0.20.13
tcp6       0      0 :::10252                :::*                    LISTEN      2952/kube-controlle 
tcp6       0      0 :::10257                :::*                    LISTEN      2952/kube-controlle

查看 kube-controller-manager 创建权限

ClusteRole system:kube-controller-manager的权限太小，只能创建secret、serviceaccount等资源,将controller的权限分散到ClusterRole system:controller:xxx中

[root@node01 work]# kubectl describe clusterrole system:kube-controller-manager
Name:         system:kube-controller-manager
Labels:       kubernetes.io/bootstrapping=rbac-defaults
Annotations:  rbac.authorization.kubernetes.io/autoupdate: true
PolicyRule:
  Resources                                  Non-Resource URLs  Resource Names  Verbs
  ---------                                  -----------------  --------------  -----
  secrets                                    []                 []              [create delete get update]
  endpoints                                  []                 []              [create get update]
  serviceaccounts                            []                 []              [create get update]
  events                                     []                 []              [create patch update]
  serviceaccounts/token                      []                 []              [create]
  tokenreviews.authentication.k8s.io         []                 []              [create]
  subjectaccessreviews.authorization.k8s.io  []                 []              [create]
  configmaps                                 []                 []              [get]
  namespaces                                 []                 []              [get]
  *.*                                        []                 []              [list watch]

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。

[root@node01 work]# kubectl get clusterrole|grep controller
system:controller:attachdetach-controller                              122m
system:controller:certificate-controller                               122m
system:controller:clusterrole-aggregation-controller                   122m
system:controller:cronjob-controller                                   122m
system:controller:daemon-set-controller                                122m
system:controller:deployment-controller                                122m
system:controller:disruption-controller                                122m
system:controller:endpoint-controller                                  122m
system:controller:expand-controller                                    122m
system:controller:generic-garbage-collector                            122m
system:controller:horizontal-pod-autoscaler                            122m
system:controller:job-controller                                       122m
system:controller:namespace-controller                                 122m
system:controller:node-controller                                      122m
system:controller:persistent-volume-binder                             122m
system:controller:pod-garbage-collector                                122m
system:controller:pv-protection-controller                             122m
system:controller:pvc-protection-controller                            122m
system:controller:replicaset-controller                                122m
system:controller:replication-controller                               122m
system:controller:resourcequota-controller                             122m
system:controller:route-controller                                     122m
system:controller:service-account-controller                           122m
system:controller:service-controller                                   122m
system:controller:statefulset-controller                               122m
system:controller:ttl-controller                                       122m
system:kube-controller-manager                                         122m

以 deployment controller 为例：

[root@node01 work]# kubectl describe clusterrole system:controller:deployment-controller
Name:         system:controller:deployment-controller
Labels:       kubernetes.io/bootstrapping=rbac-defaults
Annotations:  rbac.authorization.kubernetes.io/autoupdate: true
PolicyRule:
  Resources                          Non-Resource URLs  Resource Names  Verbs
  ---------                          -----------------  --------------  -----
  replicasets.apps                   []                 []              [create delete get list patch update watch]
  replicasets.extensions             []                 []              [create delete get list patch update watch]
  events                             []                 []              [create patch update]
  pods                               []                 []              [get list update watch]
  deployments.apps                   []                 []              [get list update watch]
  deployments.extensions             []                 []              [get list update watch]
  deployments.apps/finalizers        []                 []              [update]
  deployments.apps/status            []                 []              [update]
  deployments.extensions/finalizers  []                 []              [update]
  deployments.extensions/status      []                 []              [update]

通过apiserver查看controller-manager状态

[root@node01 work]# kubectl get cs
NAME                 STATUS      MESSAGE                                                                                     ERROR
scheduler            Unhealthy   Get http://127.0.0.1:10251/healthz: dial tcp 127.0.0.1:10251: connect: connection refused 
controller-manager   Healthy     ok                                                                                          
etcd-0               Healthy     {"health":"true"}                                                                           
etcd-2               Healthy     {"health":"true"}                                                                           
etcd-1               Healthy     {"health":"true"}

这里看到 controller-manager 的状态已经是 ok 了，在 测试访问apiserver状态 看到的还是 scheduler 是会一样的。