kublet 运行在每个 worker 节点上，接收 kube-apiserver 发送的请求，管理 Pod 容器，执行交互式命令，如 exec、run、logs 等。

kublet 启动时自动向 kube-apiserver 注册节点信息，内置的 cadvisor 统计和监控节点的资源使用情况。

为确保安全，本文档只开启接收 https 请求的安全端口，对请求进行认证和授权，拒绝未授权的访问 (如 apiserver、heapster)。

下载分发，在部署 master 节点时已经做过，依赖包也在 work 节点当中安装过，现在直接进入配置

1、创建 kubelet bootstrap kubeconfig 文件

cat > magic57_create_kubeconfig_file.sh << "EOF"
#!/bin/bash
# 创建 kubelet bootstrap kubeconfig 文件
source /opt/k8s/bin/environment.sh
for node_name in ${NODE_NAMES[@]}
do
    echo ">>> ${node_name}"
    # 创建 token
    export BOOTSTRAP_TOKEN=$(kubeadm token create \
      --description kubelet-bootstrap-token \
      --groups system:bootstrappers:${node_name} \
      --kubeconfig ~/.kube/config)
    # 设置集群参数
    kubectl config set-cluster kubernetes \
      --certificate-authority=/etc/kubernetes/cert/ca.pem \
      --embed-certs=true \
      --server=${KUBE_APISERVER} \
      --kubeconfig=kubelet-bootstrap-${node_name}.kubeconfig
    # 设置客户端认证参数
    kubectl config set-credentials kubelet-bootstrap \
      --token=${BOOTSTRAP_TOKEN} \
      --kubeconfig=kubelet-bootstrap-${node_name}.kubeconfig
    # 设置上下文参数
    kubectl config set-context default \
      --cluster=kubernetes \
      --user=kubelet-bootstrap \
      --kubeconfig=kubelet-bootstrap-${node_name}.kubeconfig
    # 设置默认上下文
    kubectl config use-context default --kubeconfig=kubelet-bootstrap-${node_name}.kubeconfig
done
EOF

• 证书中写入 Token 而非证书，证书后续由 controller-manager 创建

查看 kubeadm 为各节点创建的 token：

kubeadm token list --kubeconfig ~/.kube/config
TOKEN   TTL    EXPIRES                     USAGES                   DESCRIPTION               EXTRA GROUPS
XX.XX   XXh    20XX-XX-XXTXX:XX:XX+XX:XX   authentication,signing   kubelet-bootstrap-token   system:bootstrappers:kube-node2
XX.XX   XXh    20XX-XX-XXTXX:XX:XX+XX:XX   authentication,signing   kubelet-bootstrap-token   system:bootstrappers:kube-node3
XX.XX   XXh    20XX-XX-XXTXX:XX:XX+XX:XX   authentication,signing   kubelet-bootstrap-token   system:bootstrappers:kube-node1

• 创建的 token 有效期为 1 天，超期后将不能再被使用，且会被 kube-controller-manager 的 tokencleaner 清理 (如果启用该 controller 的话)；
• kube-apiserver 接收 kubelet 的 bootstrap token 后，将请求的 user 设置为 system:bootstrap:，group 设置为 system:bootstrappers；

各 token 关联的 Secret：

kubectl get secrets  -n kube-system
NAME                                     TYPE                                  DATA      AGE
bootstrap-token-3v99js                   bootstrap.kubernetes.io/token         7         6h
bootstrap-token-904crw                   bootstrap.kubernetes.io/token         7         6h
bootstrap-token-v75f7h                   bootstrap.kubernetes.io/token         7         6h
default-token-sqk8s                      kubernetes.io/service-account-token   3         6h

2、分发 bootstrap kubeconfig 文件到所有 worker 节点

cat > magic58_distribute_kubeconfig_file.sh << "EOF"
#!/bin/bash
# 分发 bootstrap kubeconfig 文件到所有 worker 节点
source /opt/k8s/bin/environment.sh
for node_name in ${NODE_NAMES[@]}
do
    echo ">>> ${node_name}" 
    scp kubelet-bootstrap-${node_name}.kubeconfig k8s@${node_name}:/etc/kubernetes/kubelet-bootstrap.kubeconfig
done
EOF

3、创建和分发 kubelet 参数配置文件

创建 kubelet 参数配置模板文件：

source /opt/k8s/bin/environment.sh

cat > kubelet.config.json.template <<EOF
{
  "kind": "KubeletConfiguration",
  "apiVersion": "kubelet.config.k8s.io/v1beta1",
  "authentication": {
    "x509": {
      "clientCAFile": "/etc/kubernetes/cert/ca.pem"
    },
    "webhook": {
      "enabled": true,
      "cacheTTL": "2m0s"
    },
    "anonymous": {
      "enabled": false
    }
  },
  "authorization": {
    "mode": "Webhook",
    "webhook": {
      "cacheAuthorizedTTL": "5m0s",
      "cacheUnauthorizedTTL": "30s"
    }
  },
  "address": "##NODE_IP##",
  "port": 10250,
  "readOnlyPort": 0,
  "cgroupDriver": "cgroupfs",
  "hairpinMode": "promiscuous-bridge",
  "serializeImagePulls": false,
  "featureGates": {
    "RotateKubeletClientCertificate": true,
    "RotateKubeletServerCertificate": true
  },
  "clusterDomain": "${CLUSTER_DNS_DOMAIN}",
  "clusterDNS": ["${CLUSTER_DNS_SVC_IP}"]
}
EOF

• address：API 监听地址，不能为 127.0.0.1，否则 kube-apiserver、heapster 等不能调用 kubelet 的 API；
• readOnlyPort=0：关闭只读端口 (默认 10255)，等效为未指定；
• authentication.anonymous.enabled：设置为 false，不允许匿名访问 10250 端口；
• authentication.x509.clientCAFile：指定签名客户端证书的 CA 证书，开启 HTTP 证书认证；
• authentication.webhook.enabled=true：开启 HTTPs bearer token 认证；
• 对于未通过 x509 证书和 webhook 认证的请求 (kube-apiserver 或其他客户端)，将被拒绝，提示 Unauthorized；
• authroization.mode=Webhook：kubelet 使用 SubjectAccessReview API 查询 kube-apiserver 某 user、group 是否具有操作资源的权限 (RBAC)；
• featureGates.RotateKubeletClientCertificate、featureGates.RotateKubeletServerCertificate：自动 rotate 证书，证书的有效期取决于 kube-controller-manager 的 –experimental-cluster-signing-duration 参数；
• 需要 root 账户运行；

为各节点创建和分发 kubelet 配置文件：

cat > magic59_createNode_distribute_file.sh << "EOF"
#!/bin/bash
# 为各节点创建和分发 kubelet 配置文件
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
    echo ">>> ${node_ip}" 
    sed -e "s/##NODE_IP##/${node_ip}/" kubelet.config.json.template > kubelet.config-${node_ip}.json
    scp kubelet.config-${node_ip}.json root@${node_ip}:/etc/kubernetes/kubelet.config.json
done
EOF

4、创建和分发 kubelet systemd unit 文件

创建 kubelet systemd unit 文件模板：

cat > kubelet.service.template <<EOF
[Unit]
Description=Kubernetes Kubelet
Documentation=https://github.com/GoogleCloudPlatform/kubernetes
After=docker.service
Requires=docker.service
[Service]
WorkingDirectory=/var/lib/kubelet
ExecStart=/opt/k8s/bin/kubelet \\
  --bootstrap-kubeconfig=/etc/kubernetes/kubelet-bootstrap.kubeconfig \\
  --cert-dir=/etc/kubernetes/cert \\
  --kubeconfig=/etc/kubernetes/kubelet.kubeconfig \\
  --config=/etc/kubernetes/kubelet.config.json \\
  --hostname-override=##NODE_NAME## \\
  --pod-infra-container-image=registry.access.redhat.com/rhel7/pod-infrastructure:latest \\
  --allow-privileged=true \\
  --alsologtostderr=true \\
  --logtostderr=false \\
  --log-dir=/var/log/kubernetes \\
  --v=2
Restart=on-failure
RestartSec=5
[Install]
WantedBy=multi-user.target
EOF

• 如果设置了 --hostname-override 选项，则 kube-proxy 也需要设置该选项，否则会出现找不到 Node 的情况；
• --bootstrap-kubeconfig：指向 bootstrap kubeconfig 文件，kubelet 使用该文件中的用户名和 token 向 kube-apiserver 发送 TLS Bootstrapping 请求；
• K8S approve kubelet 的 csr 请求后，在 --cert-dir 目录创建证书和私钥文件，然后写入 --kubeconfig 文件

为各节点创建和分发 kubelet systemd unit 文件：

cat > magic60_create_distribute_kubelet_file.sh << "EOF"
#!/bin/bash
# 为各节点创建和分发 kubelet systemd unit 文件
source /opt/k8s/bin/environment.sh
for node_name in ${NODE_NAMES[@]}
do 
    echo ">>> ${node_name}"
    sed -e "s/##NODE_NAME##/${node_name}/" kubelet.service.template > kubelet-${node_name}.service
    scp kubelet-${node_name}.service root@${node_name}:/etc/systemd/system/kubelet.service
    scp kubelet-bootstrap-${node_name}.kubeconfig root@${node_name}:/etc/kubernetes/kubelet-bootstrap.kubeconfig
done
EOF

5、Bootstrap Token Auth 和授予权限

kublet 启动时查找配置的 –kubeletconfig 文件是否存在，如果不存在则使用 --bootstrap-kubeconfig 向 kube-apiserver 发送证书签名请求 (CSR)。

kube-apiserver 收到 CSR 请求后，对其中的 Token 进行认证（事先使用 kubeadm 创建的 token），认证通过后将请求的 user 设置为 system:bootstrap:，group 设置为 system:bootstrappers，这一过程称为 Bootstrap Token Auth。

默认情况下，这个 user 和 group 没有创建 CSR 的权限，kubelet 启动失败，错误日志如下：

sudo journalctl -u kubelet -a |grep -A 2 'certificatesigningrequests'
XX XX XX:XX:XX kube-node1 kubelet[26986]: F0506 XX:XX:XX.314378   26986 server.go:233] failed to run Kubelet: cannot create certificate signing request: certificatesigningrequests.certificates.k8s.io is forbidden: User "system:bootstrap:lemy40" cannot create certificatesigningrequests.certificates.k8s.io at the cluster scope
XX XX XX:XX:XX kube-node1 systemd[1]: kubelet.service: Main process exited, code=exited, status=255/n/a
XX XX XX:XX:XX kube-node1 systemd[1]: kubelet.service: Failed with result 'exit-code'.

解决：创建一个 clusterrolebinding 将 group system:bootstrappers 和 clusterrole system:node-bootstrapper 绑定

kubectl create clusterrolebinding kubelet-bootstrap \
  --clusterrole=system:node-bootstrapper \
  --group=system:bootstrappers

6、启动 kubelet 服务

cat > magic61_start_kubelet_server.sh << "EOF"
#!/bin/bash
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
do
    echo ">>> ${node_ip}" 
    ssh root@${node_ip} "mkdir -p /var/lib/kubelet"
    ssh root@${node_ip} "/usr/sbin/swapoff -a"
    ssh root@${node_ip} "mkdir -p /var/log/kubernetes && chown -R k8s /var/log/kubernetes"
    ssh root@${node_ip} "systemctl daemon-reload && systemctl enable kubelet && systemctl restart kubelet"
done
EOF

• 关闭 swap 分区，否则 kubelet 会启动失败；
• 必须先创建工作和日志目录；

journalctl -u kubelet |tail
XX XX XX:XX:XX kube-node1 kubelet[17331]: I1124 XX:XX:XX.255251   17331 container_manager_linux.go:427] [ContainerManager]: Discovered runtime cgroups name: /system.slice/docker.service
XX XX XX:XX:XX kube-node1 kubelet[17331]: I1124 XX:XX:XX.255711   17331 container_manager_linux.go:427] [ContainerManager]: Discovered runtime cgroups name: 
...........

kubelet 启动后使用 --bootstrap-kubeconfig 向 kube-apiserver 发送 CSR 请求，当这个 CSR 被 approve 后，kube-controller-manager 为 kubelet 创建 TLS 客户端证书、私钥和 --kubeletconfig 文件。
注意：kube-controller-manager 需要配置 --cluster-signing-cert-file 和 --cluster-signing-key-file 参数，才会为 TLS Bootstrap 创建证书和私钥

kubectl get csr
NAME                                                   AGE       REQUESTOR                 CONDITION
node-csr-QzuuQiuUfcSdp3j5W4B2UOuvQ_n9aTNHAlrLzVFiqrk   43s       system:bootstrap:zkiem5   Pending
node-csr-oVbPmU-ikVknpynwu0Ckz_MvkAO_F1j0hmbcDa__sGA   27s       system:bootstrap:mkus5s   Pending
node-csr-u0E1-ugxgotO_9FiGXo8DkD6a7-ew8sX2qPE6KPS2IY   13m       system:bootstrap:k0s2bj   Pending

kubectl get nodes
  No resources found.

• 三个 work 节点的 csr 均处于 pending 状态

1）approve kubelet CSR 请求
可以手动或自动 approve CSR 请求。推荐使用自动的方式，因为从 v1.8 版本开始，可以自动轮转 approve csr 后生成的证书

2）手动 approve CSR 请求
查看 CSR 列表：

kubectl get csr
NAME                                                   AGE       REQUESTOR                 CONDITION
node-csr-QzuuQiuUfcSdp3j5W4B2UOuvQ_n9aTNHAlrLzVFiqrk   43s       system:bootstrap:zkiem5   Pending
node-csr-oVbPmU-ikVknpynwu0Ckz_MvkAO_F1j0hmbcDa__sGA   27s       system:bootstrap:mkus5s   Pending
node-csr-u0E1-ugxgotO_9FiGXo8DkD6a7-ew8sX2qPE6KPS2IY   13m       system:bootstrap:k0s2bj   Pending

approve CSR：

kubectl certificate approve node-csr-QzuuQiuUfcSdp3j5W4B2UOuvQ_n9aTNHAlrLzVFiqrk
certificatesigningrequest.certificates.k8s.io "node-csr-QzuuQiuUfcSdp3j5W4B2UOuvQ_n9aTNHAlrLzVFiqrk" approved

查看 Approve 结果：

kubectl describe  csr node-csr-QzuuQiuUfcSdp3j5W4B2UOuvQ_n9aTNHAlrLzVFiqrk
Name:               node-csr-QzuuQiuUfcSdp3j5W4B2UOuvQ_n9aTNHAlrLzVFiqrk
Labels:             <none>
Annotations:        <none>
CreationTimestamp:  Wed, XX XX 20XX XX:XX:XX +0800
Requesting User:    system:bootstrap:zkiem5
Status:             Approved
Subject:
         Common Name:    system:node:kube-node2
         Serial Number:
         Organization:   system:nodes
Events:  <none>

• Requesting User：请求 CSR 的用户，kube-apiserver 对它进行认证和授权；
• Subject：请求签名的证书信息；
• 证书的 CN 是 system:node:kube-node2， Organization 是 system:nodes，kube-apiserver 的 Node 授权模式会授予该证书的相关权限；

3）自动 approve CSR 请求
创建三个 ClusterRoleBinding，分别用于自动 approve client、renew client、renew server 证书：

cat > csr-crb.yaml <<EOF
 # Approve all CSRs for the group "system:bootstrappers"
 kind: ClusterRoleBinding
 apiVersion: rbac.authorization.k8s.io/v1
 metadata:
   name: auto-approve-csrs-for-group
 subjects:
 - kind: Group
   name: system:bootstrappers
   apiGroup: rbac.authorization.k8s.io
 roleRef:
   kind: ClusterRole
   name: system:certificates.k8s.io:certificatesigningrequests:nodeclient
   apiGroup: rbac.authorization.k8s.io
---
 # To let a node of the group "system:nodes" renew its own credentials
 kind: ClusterRoleBinding
 apiVersion: rbac.authorization.k8s.io/v1
 metadata:
   name: node-client-cert-renewal
 subjects:
 - kind: Group
   name: system:nodes
   apiGroup: rbac.authorization.k8s.io
 roleRef:
   kind: ClusterRole
   name: system:certificates.k8s.io:certificatesigningrequests:selfnodeclient
   apiGroup: rbac.authorization.k8s.io
---
# A ClusterRole which instructs the CSR approver to approve a node requesting a
# serving cert matching its client cert.
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: approve-node-server-renewal-csr
rules:
- apiGroups: ["certificates.k8s.io"]
  resources: ["certificatesigningrequests/selfnodeserver"]
  verbs: ["create"]
---
 # To let a node of the group "system:nodes" renew its own server credentials
 kind: ClusterRoleBinding
 apiVersion: rbac.authorization.k8s.io/v1
 metadata:
   name: node-server-cert-renewal
 subjects:
 - kind: Group
   name: system:nodes
   apiGroup: rbac.authorization.k8s.io
 roleRef:
   kind: ClusterRole
   name: approve-node-server-renewal-csr
   apiGroup: rbac.authorization.k8s.io
EOF

• auto-approve-csrs-for-group：自动 approve node 的第一次 CSR； 注意第一次 CSR 时，请求的 Group 为 system:bootstrappers；
• node-client-cert-renewal：自动 approve node 后续过期的 client 证书，自动生成的证书 Group 为 system:nodes;
• node-server-cert-renewal：自动 approve node 后续过期的 server 证书，自动生成的证书 Group 为 system:nodes;

生效配置：

kubectl apply -f csr-crb.yaml

7、查看 kublet 的情况

等待一段时间 (1-10 分钟)，三个节点的 CSR 都被自动 approve：

kubectl get csr
NAME                                                   AGE       REQUESTOR                 CONDITION
csr-98h25                                              6m        system:node:kube-node2    Approved,Issued
csr-lb5c9                                              7m        system:node:kube-node3    Approved,Issued
csr-m2hn4                                              14m       system:node:kube-node1    Approved,Issued
node-csr-7q7i0q4MF_K2TSEJj16At4CJFLlJkHIqei6nMIAaJCU   28m       system:bootstrap:k0s2bj   Approved,Issued
node-csr-ND77wk2P8k2lHBtgBaObiyYw0uz1Um7g2pRvveMF-c4   35m       system:bootstrap:mkus5s   Approved,Issued
node-csr-Nysmrw55nnM48NKwEJuiuCGmZoxouK4N8jiEHBtLQso   6m        system:bootstrap:zkiem5   Approved,Issued
node-csr-QzuuQiuUfcSdp3j5W4B2UOuvQ_n9aTNHAlrLzVFiqrk   1h        system:bootstrap:zkiem5   Approved,Issued
node-csr-oVbPmU-ikVknpynwu0Ckz_MvkAO_F1j0hmbcDa__sGA   1h        system:bootstrap:mkus5s   Approved,Issued
node-csr-u0E1-ugxgotO_9FiGXo8DkD6a7-ew8sX2qPE6KPS2IY   1h        system:bootstrap:k0s2bj   Approved,Issued

所有节点均 ready：

kubectl get node
NAME         STATUS    ROLES     AGE       VERSION
kube-node1   Ready     <none>    6h        v1.10.4
kube-node2   Ready     <none>    6h        v1.10.4
kube-node3   Ready     <none>    6h        v1.10.4

kube-controller-manager 为各 node 生成了 kubeconfig 文件和公私钥：

ls -l /etc/kubernetes/kubelet.kubeconfig
-rw------- 1 root root 2296 XX XX XX:XX /etc/kubernetes/kubelet.kubeconfig

ls -l /etc/kubernetes/cert/|grep kubelet
-rw-r--r-- 1 root root 1046 XX XX XX:XX kubelet-client.crt
-rw------- 1 root root  227 XX XX XX:XX kubelet-client.key
-rw------- 1 root root 1334 XX XX XX:XX kubelet-server-20XX-XX-XX-XX-XX-XX.pem
lrwxrwxrwx 1 root root   59 XX XX XX:XX kubelet-server-current.pem -> /etc/kubernetes/cert/kubelet-server-20XX-XX-XX-XX-XX-XX.pem

• kubelet-server 证书会周期轮转；

8、kubelet 提供的 API 接口

kublet 启动后监听多个端口，用于接收 kube-apiserver 或其它组件发送的请求：

sudo netstat -lnpt|grep kubelet
tcp        0      0 172.68.96.101:10250     0.0.0.0:*               LISTEN      17331/kubelet
tcp        0      0 172.68.96.101:4194      0.0.0.0:*               LISTEN      17331/kubelet
tcp        0      0 127.0.0.1:10248         0.0.0.0:*               LISTEN      17331/kubelet

• 4194: cadvisor http 服务；
• 10248: healthz http 服务；
• 10250: https API 服务；注意：未开启只读端口 10255；

例如执行 kubectl exec -it nginx-ds-5rmws -- sh 命令时，kube-apiserver 会向 kubelet 发送如下请求：

POST /exec/default/nginx-ds-5rmws/my-nginx?command=sh&input=1&output=1&tty=1

kubelet 接收 10250 端口的 https 请求：

• /pods、/runningpods
• /metrics、/metrics/cadvisor、/metrics/probes
• /spec
• /stats、/stats/container
• /logs
• /run/、”/exec/”, “/attach/”, “/portForward/”, “/containerLogs/” 等管理

详情参考：https://github.com/kubernetes/kubernetes/blob/master/pkg/kubelet/server/server.go#L434:3

由于关闭了匿名认证，同时开启了 webhook 授权，所有访问 10250 端口 https API 的请求都需要被认证和授权。

预定义的 ClusterRole system:kubelet-api-admin 授予访问 kubelet 所有 API 的权限：

kubectl describe clusterrole system:kubelet-api-admin
Name:         system:kubelet-api-admin
Labels:       kubernetes.io/bootstrapping=rbac-defaults
Annotations:  rbac.authorization.kubernetes.io/autoupdate=true
PolicyRule:
  Resources      Non-Resource URLs  Resource Names  Verbs
  ---------      -----------------  --------------  -----
  nodes          []                 []              [get list watch proxy]
  nodes/log      []                 []              [*]
  nodes/metrics  []                 []              [*]
  nodes/proxy    []                 []              [*]
  nodes/spec     []                 []              [*]
  nodes/stats    []                 []              [*]

9、kublet api 认证和授权

kublet 配置了如下认证参数：

• authentication.anonymous.enabled：设置为 false，不允许匿名访问 10250 端口
• authentication.x509.clientCAFile：指定签名客户端证书的 CA 证书，开启 HTTPs 证书认证
• authentication.webhook.enabled=true：开启 HTTPs bearer token 认证；

同时配置了如下授权参数：

• authroization.mode=Webhook：开启 RBAC 授权；

kubelet 收到请求后，使用 clientCAFile 对证书签名进行认证，或者查询 bearer token 是否有效。如果两者都没通过，则拒绝请求，提示 Unauthorized

curl -s --cacert /etc/kubernetes/cert/ca.pem https://172.68.96.103:10250/metrics
Unauthorized

curl -s --cacert /etc/kubernetes/cert/ca.pem -H "Authorization: Bearer 123456" https://172.68.96.103:10250/metrics
Unauthorized

通过认证后，kubelet 使用 SubjectAccessReview API 向 kube-apiserver 发送请求，查询证书或 token 对应的 user、group 是否有操作资源的权限 (RBAC)；

证书认证和授权：

# 权限不足的证书；
curl -s --cacert /etc/kubernetes/cert/ca.pem --cert /etc/kubernetes/cert/kube-controller-manager.pem --key /etc/kubernetes/cert/kube-controller-manager-key.pem https://172.68.96.103:10250/metrics
Forbidden (user=system:kube-controller-manager, verb=get, resource=nodes, subresource=metrics)

# 使用部署 kubectl 命令行工具时创建的、具有最高权限的 admin 证书；
curl -s --cacert /etc/kubernetes/cert/ca.pem --cert ./admin.pem --key ./admin-key.pem https://172.68.96.103:10250/metrics|head
# HELP apiserver_client_certificate_expiration_seconds Distribution of the remaining lifetime on the certificate used to authenticate a request.
# TYPE apiserver_client_certificate_expiration_seconds histogram
apiserver_client_certificate_expiration_seconds_bucket{le="0"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="21600"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="43200"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="86400"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="172800"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="345600"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="604800"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="2.592e+06"} 0

• --cacert、--cert、--key 的参数值必须是文件路径，如上面的 ./admin.pem 不能省略 ./，否则返回 401 Unauthorized；

bear token 认证和授权：

创建一个 ServiceAccount，将它和 ClusterRole system:kubelet-api-admin 绑定，从而具有调用 kubelet API 的权限：

kubectl create sa kubelet-api-test
kubectl create clusterrolebinding kubelet-api-test --$clusterrole=system:kubelet-api-admin --

serviceaccount=default:kubelet-api-test
SECRET=$(kubectl get secrets | grep kubelet-api-test | awk '{print $1}')
TOKEN=$(kubectl describe secret ${SECRET} | grep -E '^token' | awk '{print $2}')
echo ${TOKEN}

curl -s --cacert /etc/kubernetes/cert/ca.pem -H "Authorization: Bearer ${TOKEN}" https://172.27.129.111:10250/metrics|head
# HELP apiserver_client_certificate_expiration_seconds Distribution of the remaining lifetime on the certificate used to authenticate a request.
# TYPE apiserver_client_certificate_expiration_seconds histogram
apiserver_client_certificate_expiration_seconds_bucket{le="0"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="21600"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="43200"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="86400"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="172800"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="345600"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="604800"} 0
apiserver_client_certificate_expiration_seconds_bucket{le="2.592e+06"} 0

10，cadvisor 和 metrics

cadvisor 统计所在节点各容器的资源 (CPU、内存、磁盘、网卡) 使用情况，分别在自己的 http web 页面 (4194 端口) 和 10250 以 promehteus metrics 的形式输出

浏览器访问 http://172.68.96.103:4194/containers/ 可以查看到 cadvisor 的监控页面：

image.png

11、获取 kublet 的配置

从 kube-apiserver 获取各 node 的配置：

source /opt/k8s/bin/environment.sh

# 使用部署 kubectl 命令行工具时创建的、具有最高权限的 admin 证书；
curl -sSL --cacert /etc/kubernetes/cert/ca.pem --cert ./admin.pem --key ./admin-key.pem ${KUBE_APISERVER}/api/v1/nodes/kube-node1/proxy/configz | jq \
  '.kubeletconfig|.kind="KubeletConfiguration"|.apiVersion="kubelet.config.k8s.io/v1beta1"'
{
  "syncFrequency": "1m0s",
  "fileCheckFrequency": "20s",
  "httpCheckFrequency": "20s",
  "address": "172.27.129.80",
  "port": 10250,
  "readOnlyPort": 10255,
  "authentication": {
    "x509": {},
    "webhook": {
      "enabled": false,
      "cacheTTL": "2m0s"
    },
    "anonymous": {
      "enabled": true
    }
  },
  "authorization": {
    "mode": "AlwaysAllow",
    "webhook": {
      "cacheAuthorizedTTL": "5m0s",
      "cacheUnauthorizedTTL": "30s"
    }
  },
  "registryPullQPS": 5,
  "registryBurst": 10,
  "eventRecordQPS": 5,
  "eventBurst": 10,
  "enableDebuggingHandlers": true,
  "healthzPort": 10248,
  "healthzBindAddress": "127.0.0.1",
  "oomScoreAdj": -999,
  "clusterDomain": "cluster.local.",
  "clusterDNS": [
    "10.254.0.2"
  ],
  "streamingConnectionIdleTimeout": "4h0m0s",
  "nodeStatusUpdateFrequency": "10s",
  "imageMinimumGCAge": "2m0s",
  "imageGCHighThresholdPercent": 85,
  "imageGCLowThresholdPercent": 80,
  "volumeStatsAggPeriod": "1m0s",
  "cgroupsPerQOS": true,
  "cgroupDriver": "cgroupfs",
  "cpuManagerPolicy": "none",
  "cpuManagerReconcilePeriod": "10s",
  "runtimeRequestTimeout": "2m0s",
  "hairpinMode": "promiscuous-bridge",
  "maxPods": 110,
  "podPidsLimit": -1,
  "resolvConf": "/etc/resolv.conf",
  "cpuCFSQuota": true,
  "maxOpenFiles": 1000000,
  "contentType": "application/vnd.kubernetes.protobuf",
  "kubeAPIQPS": 5,
  "kubeAPIBurst": 10,
  "serializeImagePulls": false,
  "evictionHard": {
    "imagefs.available": "15%",
    "memory.available": "100Mi",
    "nodefs.available": "10%",
    "nodefs.inodesFree": "5%"
  },
  "evictionPressureTransitionPeriod": "5m0s",
  "enableControllerAttachDetach": true,
  "makeIPTablesUtilChains": true,
  "iptablesMasqueradeBit": 14,
  "iptablesDropBit": 15,
  "featureGates": {
    "RotateKubeletClientCertificate": true,
    "RotateKubeletServerCertificate": true
  },
  "failSwapOn": true,
  "containerLogMaxSize": "10Mi",
  "containerLogMaxFiles": 5,
  "enforceNodeAllocatable": [
    "pods"
  ],
  "kind": "KubeletConfiguration",
  "apiVersion": "kubelet.config.k8s.io/v1beta1"
}

或者参考代码中的注释：https://github.com/kubernetes/kubernetes/blob/master/pkg/kubelet/apis/kubeletconfig/v1beta1/types.go

12、参考

kubelet 认证和授权：https://kubernetes.io/docs/reference/command-line-tools-reference/kubelet-authentication-authorization/