07-2.部署 kubelet 组件

07-2.部署 kubelet 组件

kubelet 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。

kubelet 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)。

注意：如果没有特殊指明，本文档的所有操作均在 m7-autocv-gpu01 节点上执行，然后远程分发文件和执行命令。

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

cd /opt/k8s/work
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 kube-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
c77gx4.fofw4ir1628c6zk8   23h       2018-11-29T16:54:27+08:00   authentication,signing   kubelet-bootstrap-token   system:bootstrappers:m7-autocv-gpu01
em63m9.g4cemcarph6gz6vg   23h       2018-11-29T16:54:32+08:00   authentication,signing   kubelet-bootstrap-token   system:bootstrappers:m7-autocv-gpu02
mnpn4i.iqttdxlan650stmu   23h       2018-11-29T16:54:35+08:00   authentication,signing   kubelet-bootstrap-token   system:bootstrappers:m7-autocv-gpu03

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；

查看各 token 关联的 Secret：

$ kubectl get secrets  -n kube-system|grep bootstrap-token
bootstrap-token-c77gx4                           bootstrap.kubernetes.io/token         7      54s
bootstrap-token-em63m9                           bootstrap.kubernetes.io/token         7      49s
bootstrap-token-mnpn4i                           bootstrap.kubernetes.io/token         7      46s

分发 bootstrap kubeconfig 文件到所有 worker 节点

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_name in ${NODE_NAMES[@]}
  do
    echo ">>> ${node_name}"
    scp kubelet-bootstrap-${node_name}.kubeconfig root@${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：

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
cat <<EOF | tee kubelet-config.yaml.template
kind: KubeletConfiguration
apiVersion: kubelet.config.k8s.io/v1beta1
authentication:
  anonymous:
    enabled: false
  webhook:
    enabled: true
  x509:
    clientCAFile: "/etc/kubernetes/cert/ca.pem"
authorization:
  mode: Webhook
clusterDomain: "${CLUSTER_DNS_DOMAIN}"
clusterDNS:
  - "${CLUSTER_DNS_SVC_IP}"
podCIDR: "${CLUSTER_CIDR}"
maxPods: 220
serializeImagePulls: false
hairpinMode: promiscuous-bridge
cgroupDriver: cgroupfs
runtimeRequestTimeout: "15m"
rotateCertificates: true
serverTLSBootstrap: true
readOnlyPort: 0
port: 10250
address: "##NODE_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：

cd /opt/k8s/work
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.yaml.template > kubelet-config-${node_ip}.yaml.template
    scp kubelet-config-${node_ip}.yaml.template root@${node_ip}:/etc/kubernetes/kubelet-config.yaml
  done

替换后的 kubelet-config.yaml 文件： kubelet-config.yaml

创建和分发 kubelet systemd unit 文件

创建 kubelet systemd unit 文件模板：

cd /opt/k8s/work
cat > kubelet.service.template <<EOF
[Unit]
Description=Kubernetes Kubelet
Documentation=https://github.com/GoogleCloudPlatform/kubernetes
After=docker.service
Requires=docker.service
[Service]
WorkingDirectory=${K8S_DIR}/kubelet
ExecStart=/opt/k8s/bin/kubelet \\
  --root-dir=${K8S_DIR}/kubelet \\
  --bootstrap-kubeconfig=/etc/kubernetes/kubelet-bootstrap.kubeconfig \\
  --cert-dir=/etc/kubernetes/cert \\
  --kubeconfig=/etc/kubernetes/kubelet.kubeconfig \\
  --config=/etc/kubernetes/kubelet-config.yaml \\
  --hostname-override=##NODE_NAME## \\
  --pod-infra-container-image=registry.cn-beijing.aliyuncs.com/k8s_images/pause-amd64:3.1 \\
  --allow-privileged=true \\
  --event-qps=0 \\
  --kube-api-qps=1000 \\
  --kube-api-burst=2000 \\
  --registry-qps=0 \\
  --image-pull-progress-deadline=30m \\
  --logtostderr=true \\
  --v=2
Restart=always
RestartSec=5
StartLimitInterval=0
[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；
--pod-infra-container-image 不使用 redhat 的 pod-infrastructure:latest 镜像，它不能回收容器的僵尸；

替换后的 unit 文件：kubelet.service

为各节点创建和分发 kubelet systemd unit 文件：

cd /opt/k8s/work
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

kubelet 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 m7-autocv-gpu01 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 m7-autocv-gpu01 systemd[1]: kubelet.service: Main process exited, code=exited, status=255/n/a
May 06 06:42:36 m7-autocv-gpu01 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 ${K8S_DIR}/kubelet"
    ssh root@${node_ip} "/usr/sbin/swapoff -a"
    ssh root@${node_ip} "systemctl daemon-reload && systemctl enable kubelet && systemctl restart kubelet"
  done

必须创建工作目录；
关闭 swap 分区，否则 kubelet 会启动失败；

$ journalctl -u kubelet |tail
8月 15 12:16:49 m7-autocv-gpu01 kubelet[7807]: I0815 12:16:49.578598    7807 feature_gate.go:230] feature gates: &{map[RotateKubeletClientCertificate:true RotateKubeletServerCertificate:true]}
8月 15 12:16:49 m7-autocv-gpu01 kubelet[7807]: I0815 12:16:49.578698    7807 feature_gate.go:230] feature gates: &{map[RotateKubeletClientCertificate:true RotateKubeletServerCertificate:true]}
8月 15 12:16:50 m7-autocv-gpu01 kubelet[7807]: I0815 12:16:50.205871    7807 mount_linux.go:214] Detected OS with systemd
8月 15 12:16:50 m7-autocv-gpu01 kubelet[7807]: I0815 12:16:50.205939    7807 server.go:408] Version: v1.11.2
8月 15 12:16:50 m7-autocv-gpu01 kubelet[7807]: I0815 12:16:50.206013    7807 feature_gate.go:230] feature gates: &{map[RotateKubeletClientCertificate:true RotateKubeletServerCertificate:true]}
8月 15 12:16:50 m7-autocv-gpu01 kubelet[7807]: I0815 12:16:50.206101    7807 feature_gate.go:230] feature gates: &{map[RotateKubeletServerCertificate:true RotateKubeletClientCertificate:true]}
8月 15 12:16:50 m7-autocv-gpu01 kubelet[7807]: I0815 12:16:50.206217    7807 plugins.go:97] No cloud provider specified.
8月 15 12:16:50 m7-autocv-gpu01 kubelet[7807]: I0815 12:16:50.206237    7807 server.go:524] No cloud provider specified: "" from the config file: ""
8月 15 12:16:50 m7-autocv-gpu01 kubelet[7807]: I0815 12:16:50.206264    7807 bootstrap.go:56] Using bootstrap kubeconfig to generate TLS client cert, key and kubeconfig file
8月 15 12:16:50 m7-autocv-gpu01 kubelet[7807]: I0815 12:16:50.208628    7807 bootstrap.go:86] No valid private key and/or certificate found, reusing existing private key or creating a new one

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--BjlTzxB5Y4op_6wYlDKbbQj1NtX-IOBMLmWhkupEWA   22s       system:bootstrap:8galm1   Pending
node-csr-a68FhmUgprTJkaLwnJOLQLOkDQuAviDdBy91ByVtWt0   28s       system:bootstrap:4ef7hj   Pending
node-csr-a7DI6d0QjBiPh58IBGYFPUKAZvKs6sfbqlnoc22erRs   27s       system:bootstrap:ai162m   Pending
$ kubectl get nodes
No resources found.

三个 work 节点的 csr 均处于 pending 状态；

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：

cd /opt/k8s/work
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 kubelet 的情况

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

$ kubectl get csr
NAME                                                   AGE       REQUESTOR                 CONDITION
node-csr--BjlTzxB5Y4op_6wYlDKbbQj1NtX-IOBMLmWhkupEWA   4m        system:bootstrap:8galm1   Approved,Issued
node-csr-a68FhmUgprTJkaLwnJOLQLOkDQuAviDdBy91ByVtWt0   4m        system:bootstrap:4ef7hj   Approved,Issued
node-csr-a7DI6d0QjBiPh58IBGYFPUKAZvKs6sfbqlnoc22erRs   4m        system:bootstrap:ai162m   Approved,Issued

所有节点均 ready：

$ kubectl get nodes
NAME              STATUS   ROLES    AGE     VERSION
m7-autocv-gpu03   Ready    <none>   4m12s   v1.12.3
m7-autocv-gpu02   Ready    <none>   4m13s   v1.12.3
m7-autocv-gpu01     Ready    <none>   12s     v1.12.3

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 2306 11月 28 17:20 /etc/kubernetes/kubelet.kubeconfig
$ ls -l /etc/kubernetes/cert/|grep kubelet
-rw------- 1 root root 1277 11月 28 17:20 kubelet-client-2018-11-28-17-20-06.pem
lrwxrwxrwx 1 root root   59 11月 28 17:20 kubelet-client-current.pem -> /etc/kubernetes/cert/kubelet-client-2018-11-28-17-20-06.pem

没有自动生成 kubelet server 证书；

手动 approve server cert csr

基于安全性考虑，CSR approving controllers 默认不会自动 approve kubelet server 证书签名请求，需要手动 approve。

$ kubectl get csr
NAME                                                   AGE     REQUESTOR                     CONDITION
csr-lrhk2                                              9m25s   system:node:m7-autocv-gpu03   Pending
csr-pkglb                                              5m24s   system:node:m7-autocv-gpu01     Pending
csr-xdgcl                                              9m25s   system:node:m7-autocv-gpu02   Pending
node-csr-BiCW4F3aeIQ-lQRDIRtxrK0SE967asfomI9iXKw7xFw   12m     system:bootstrap:c77gx4       Approved,Issued
node-csr-KBdQuwtHW6CgTAxtQ1PR5L0-2pL4lhH6D8z0ySeWOdg   10m     system:bootstrap:mnpn4i       Approved,Issued
node-csr-dZh_5jzWiaXVHtOd6du4aiELSDbUNQ-sDvEnSNfZtYQ   10m     system:bootstrap:em63m9       Approved,Issued
$ kubectl certificate approve csr-lrhk2
certificatesigningrequest.certificates.k8s.io/csr-lrhk2 approved
$ kubectl certificate approve csr-pkglb
certificatesigningrequest.certificates.k8s.io/csr-pkglb approved
$ kubectl certificate approve csr-xdgcl
certificatesigningrequest.certificates.k8s.io/csr-xdgcl approved
$ ls -l /etc/kubernetes/cert/kubelet-*
-rw------- 1 root root 1277 11月 28 17:20 /etc/kubernetes/cert/kubelet-client-2018-11-28-17-20-06.pem
lrwxrwxrwx 1 root root   59 11月 28 17:20 /etc/kubernetes/cert/kubelet-client-current.pem -> /etc/kubernetes/cert/kubelet-client-2018-11-28-17-20-06.pem
-rw------- 1 root root 1326 11月 28 17:25 /etc/kubernetes/cert/kubelet-server-2018-11-28-17-25-44.pem
lrwxrwxrwx 1 root root   59 11月 28 17:25 /etc/kubernetes/cert/kubelet-server-current.pem -> /etc/kubernetes/cert/kubelet-server-2018-11-28-17-25-44.pem

kubelet 提供的 API 接口

kubelet 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      0 127.0.0.1:10248         0.0.0.0:*               LISTEN      73487/kubelet
tcp        0      0 172.27.128.150:10250    0.0.0.0:*               LISTEN      73487/kubelet

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(kube-apiserver 使用的 kubernetes 证书 User 授予了该权限)：

$ 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    []                 []              [*]

kubelet api 认证和授权

kubelet 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://172.27.128.149:10250/metrics
Unauthorized
$ curl -s --cacert /etc/kubernetes/cert/ca.pem -H "Authorization: Bearer 123456" https://172.27.128.149:10250/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；
$ sudo 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://172.27.128.149:10250/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；
$ sudo curl -s --cacert /etc/kubernetes/cert/ca.pem --cert /opt/k8s/work/admin.pem --key /opt/k8s/work/admin-key.pem https://172.27.128.149:10250/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://172.27.128.149:10250/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://172.27.129.149:10250/metrics 和 https://172.27.129.149:10250/metrics/cadvisor 分别返回 kubelet 和 cadvisor 的 metrics。

注意：

kubelet.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 kubelet 的配置

从 kube-apiserver 获取各 node 的配置：

$ # 使用部署 kubectl 命令行工具时创建的、具有最高权限的 admin 证书；
$ source /opt/k8s/bin/environment.sh
$ sudo curl -sSL --cacert /etc/kubernetes/cert/ca.pem --cert /opt/k8s/work/admin.pem --key /opt/k8s/work/admin-key.pem ${KUBE_APISERVER}/api/v1/nodes/m7-autocv-gpu01/proxy/configz | jq \
  '.kubeletconfig|.kind="KubeletConfiguration"|.apiVersion="kubelet.config.k8s.io/v1beta1"'
{
  "syncFrequency": "1m0s",
  "fileCheckFrequency": "20s",
  "httpCheckFrequency": "20s",
  "address": "172.27.128.150",
  "port": 10250,
  "rotateCertificates": true,
  "serverTLSBootstrap": true,
  "authentication": {
    "x509": {
      "clientCAFile": "/etc/kubernetes/cert/ca.pem"
    },
    "webhook": {
      "enabled": true,
      "cacheTTL": "2m0s"
    },
    "anonymous": {
      "enabled": false
    }
  },
  "authorization": {
    "mode": "Webhook",
    "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": 2000,
  "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"
}