07-2.部署 kubelet 组件

07-2.部署 kubelet 组件

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)。

下载和分发 kubelet 二进制文件

参考 06-0.部署master节点.md

安装依赖包

参考 07-0.部署worker节点.md

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

• 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
k0s2bj.7nvw1zi1nalyz4gz   23h       2018-06-14T15:14:31+08:00   authentication,signing   kubelet-bootstrap-token   system:bootstrappers:kube-node1
mkus5s.vilnjk3kutei600l   23h       2018-06-14T15:14:32+08:00   authentication,signing   kubelet-bootstrap-token   system:bootstrappers:kube-node3
zkiem5.0m4xhw0jc8r466nk   23h       2018-06-14T15:14:32+08:00   authentication,signing   kubelet-bootstrap-token   system:bootstrappers:kube-node2

• 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-k0s2bj   bootstrap.kubernetes.io/token         7         1m
bootstrap-token-mkus5s   bootstrap.kubernetes.io/token         7         1m
bootstrap-token-zkiem5   bootstrap.kubernetes.io/token         7         1m
default-token-99st7      kubernetes.io/service-account-token   3         2d

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

创建和分发 kubelet 参数配置文件

从 v1.10 开始，kubelet 部分参数需在配置文件中配置，kubelet --help 会提示：

DEPRECATED: This parameter should be set via the config file specified by the Kubelet's --config flag

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：

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

替换后的 kubelet.config.json 文件： kubelet.config.json

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；

替换后的 unit 文件：kubelet.service

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
  done

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'
May 06 06:42:36 kube-node1 kubelet[26986]: F0506 06:42:36.314378   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
May 06 06:42:36 kube-node1 systemd[1]: kubelet.service: Main process exited, code=exited, status=255/n/a
May 06 06:42:36 kube-node1 systemd[1]: kubelet.service: Failed with result 'exit-code'.

解决办法是：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

启动 kubelet 服务

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

• 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
Jun 13 16:05:40 kube-node2 kubelet[22343]: I0613 16:05:40.388242   22343 feature_gate.go:226] feature gates: &{{} map[RotateKubeletServerCertificate:true RotateKubeletClientCertificate:true]}
Jun 13 16:05:40 kube-node2 kubelet[22343]: I0613 16:05:40.394342   22343 mount_linux.go:211] Detected OS with systemd
Jun 13 16:05:40 kube-node2 kubelet[22343]: W0613 16:05:40.394494   22343 cni.go:171] Unable to update cni config: No networks found in /etc/cni/net.d
Jun 13 16:05:40 kube-node2 kubelet[22343]: I0613 16:05:40.399508   22343 server.go:376] Version: v1.10.4
Jun 13 16:05:40 kube-node2 kubelet[22343]: I0613 16:05:40.399583   22343 feature_gate.go:226] feature gates: &{{} map[RotateKubeletServerCertificate:true RotateKubeletClientCertificate:true]}
Jun 13 16:05:40 kube-node2 kubelet[22343]: I0613 16:05:40.399736   22343 plugins.go:89] No cloud provider specified.
Jun 13 16:05:40 kube-node2 kubelet[22343]: I0613 16:05:40.399752   22343 server.go:492] No cloud provider specified: "" from the config file: ""
Jun 13 16:05:40 kube-node2 kubelet[22343]: I0613 16:05:40.399777   22343 bootstrap.go:58] Using bootstrap kubeconfig to generate TLS client cert, key and kubeconfig file
Jun 13 16:05:40 kube-node2 kubelet[22343]: I0613 16:05:40.446068   22343 csr.go:105] csr for this node already exists, reusing
Jun 13 16:05:40 kube-node2 kubelet[22343]: I0613 16:05:40.453761   22343 csr.go:113] csr for this node is still valid

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；

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。

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, 13 Jun 2018 16:05:04 +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；

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

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 nodes
NAME         STATUS    ROLES     AGE       VERSION
kube-node1   Ready     <none>    18m       v1.10.4
kube-node2   Ready     <none>    10m       v1.10.4
kube-node3   Ready     <none>    11m       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 2293 Jun 13 17:07 /etc/kubernetes/kubelet.kubeconfig

$ ls -l /etc/kubernetes/cert/|grep kubelet
-rw-r--r-- 1 root root 1046 Jun 13 17:07 kubelet-client.crt
-rw------- 1 root root  227 Jun 13 17:07 kubelet-client.key
-rw------- 1 root root 1334 Jun 13 17:07 kubelet-server-2018-06-13-17-07-45.pem
lrwxrwxrwx 1 root root   58 Jun 13 17:07 kubelet-server-current.pem -> /etc/kubernetes/cert/kubelet-server-2018-06-13-17-07-45.pem

• kubelet-server 证书会周期轮转；

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      0 192.168.1.107:4194     0.0.0.0:*               LISTEN      2490/kubelet
tcp        0      0 127.0.0.1:10248         0.0.0.0:*               LISTEN      2490/kubelet
tcp        0      0 192.168.1.107:10250    0.0.0.0:*               LISTEN      2490/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 ec -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    []                 []              [*]

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://192.168.1.107:10250/metrics
Unauthorized

$ curl -s --cacert /etc/kubernetes/cert/ca.pem -H "Authorization: Bearer 123456" https://192.168.1.107:10250/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://192.168.1.107:10250/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://192.168.1.107:10250/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://192.168.1.107:10250/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

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 https://192.168.1.106:4194/containers/ 可以查看到 cadvisor 的监控页面：

浏览器访问 https://172.27.129.80:10250/metrics 和 https://172.27.129.80:10250/metrics/cadvisor 分别返回 kublet 和 cadvisor 的 metrics。

注意：

• kublet.config.json 设置 authentication.anonymous.enabled 为 false，不允许匿名证书访问 10250 的 https 服务；
• 参考A.浏览器访问kube-apiserver安全端口.md，创建和导入相关证书，然后访问上面的 10250 端口；

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

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