养浩然之气,做博学之人
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)。
参考 06-0.部署master节点.md
参考 07-0.部署worker节点.md
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
输出:
TOKEN TTL EXPIRES USAGES DESCRIPTION EXTRA GROUPS
k34gvt.6nr23lvd8kht3xtc 23h 2018-08-13T16:42:07+08:00 authentication,signing kubelet-bootstrap-token system:bootstrappers:docker113
ljzjlb.38ew15vj1yj1evjj 23h 2018-08-13T16:42:05+08:00 authentication,signing kubelet-bootstrap-token system:bootstrappers:docker111
vbm02q.xpgyyhar3ghumb47 23h 2018-08-13T16:42:03+08:00 authentication,signing kubelet-bootstrap-token system:bootstrappers:docker110
x1skc2.7foqzrv4iclc8i37 23h 2018-08-13T16:42:06+08:00 authentication,signing kubelet-bootstrap-token system:bootstrappers:docker112
#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
输出类似:
NAME TYPE DATA AGE
attachdetach-controller-token-pcglz kubernetes.io/service-account-token 3 5h
bootstrap-signer-token-fbwdj kubernetes.io/service-account-token 3 5h
bootstrap-token-k34gvt bootstrap.kubernetes.io/token 7 2m
bootstrap-token-ljzjlb bootstrap.kubernetes.io/token 7 2m
bootstrap-token-vbm02q bootstrap.kubernetes.io/token 7 2m
bootstrap-token-x1skc2 bootstrap.kubernetes.io/token 7 2m
source /opt/k8s/bin/environment.sh for node_name in ${NODE_NAMES[@]} do echo ">>> ${node_name}" scp kubelet-bootstrap-${node_name}.kubeconfig k8s@${node_name}:/etc/kubernetes/kubelet-bootstrap.kubeconfig done
从 v1.10 开始,kubelet 部分参数需在配置文件中配置,kubelet --help 会提示。
创建 kubelet 参数配置模板文件:
source /opt/k8s/bin/environment.sh cat > kubelet.config.json.template <<EOF { "kind": "KubeletConfiguration", "apiVersion": "kubelet.config.k8s.io/v1beta1", "authentication": { "x509": { "clientCAFile": "/etc/kubernetes/cert/ca.pem" }, "webhook": { "enabled": true, "cacheTTL": "2m0s" }, "anonymous": { "enabled": false } }, "authorization": { "mode": "Webhook", "webhook": { "cacheAuthorizedTTL": "5m0s", "cacheUnauthorizedTTL": "30s" } }, "address": "##NODE_IP##", "port": 10250, "readOnlyPort": 0, "cgroupDriver": "cgroupfs", "hairpinMode": "promiscuous-bridge", "serializeImagePulls": false, "featureGates": { "RotateKubeletClientCertificate": true, "RotateKubeletServerCertificate": true }, "clusterDomain": "${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
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:
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
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'
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
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;
#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
输出:
#NAME AGE REQUESTOR CONDITION
#node-csr-4tt1kJxrjw8gNV0Ojfm8iT_uxEugl8gRZqSH6lEKO4Y 1m system:bootstrap:x1skc2 Pending
#node-csr-INn0DxxcaB0c7HOJbIxZ_5qI31fznnCLkNZU-ChvDwc 1m system:bootstrap:vbm02q Pending
#node-csr-rnUncJ_G4M7H2AvRdBxjc6Xi7Iuz-U0Z7zclA8tl8qo 1m system:bootstrap:ljzjlb Pending
kubectl get nodes
输出:no resources found.
#三个 work 节点的 csr 均处于 pending 状态;
问题一、非Master节点kubelet起不来,原因/opt/k8s/bin/下缺少kubelet
找到部署 master 节点时解压的kubernetes 目录server,将kubelet 分发二进制文件拷贝到所有 worker节点:
source /opt/k8s/bin/environment.sh for node_ip in ${NODE_IPS[@]} do echo ">>> ${node_ip}" scp server/bin/kubelet k8s@${node_ip}:/opt/k8s/bin/ ssh k8s@${node_ip} "chmod +x /opt/k8s/bin/*" done
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。
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
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-b4v4q 4m system:node:docker113 Approved,Issued
csr-fnhx6 4m system:node:docker110 Approved,Issued
csr-kt4j6 3m system:node:docker112 Approved,Issued
csr-pcbk2 4m system:node:docker111 Approved,Issued
node-csr--jX2U4a47L5pWRDe-qfhZcWs8aJe2zE08LD6FoZhkCg 31m system:bootstrap:x1skc2 Approved,Issued
#所有节点均 ready:
kubectl get nodes
NAME STATUS ROLES AGE VERSION
docker110 Ready <none> 1m v1.10.4
docker111 Ready <none> 1m v1.10.4
docker112 Ready <none> 1m v1.10.4
docker113 Ready <none> 1m 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 2298 Aug 12 21:22 /etc/kubernetes/kubelet.kubeconfig
ls -l /etc/kubernetes/cert/|grep kubelet -rw-r--r-- 1 root root 1050 Aug 12 21:22 kubelet-client.crt -rw------- 1 root root 227 Aug 12 21:15 kubelet-client.key -rw------- 1 root root 1330 Aug 12 21:22 kubelet-server-2018-08-12-21-22-14.pem lrwxrwxrwx 1 root root 59 Aug 12 21:22 kubelet-server-current.pem -> /etc/kubernetes/cert/kubelet-server-2018-08-12-21-22-14.pem
kubelet-server 证书会周期轮转;
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 0 192.168.1.110:10250 0.0.0.0:* LISTEN 46378/kubelet #tcp 0 0 192.168.1.110:4194 0.0.0.0:* LISTEN 46378/kubelet #tcp 0 0 127.0.0.1:10248 0.0.0.0:* LISTEN 46378/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;
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 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://192.168.1.110:10250/metrics #Unauthorized curl -s --cacert /etc/kubernetes/cert/ca.pem -H "Authorization: Bearer 123456" https://192.168.1.110:10250/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://192.168.1.110:10250/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://192.168.1.110:10250/metrics|head #Unauthorized
#--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;
###################################出错
#缺少最高权限证书、在kubectl环节没有分发
for node_ip in ${NODE_IPS[@]} do echo ">>> ${node_ip}" scp kubectl/admin*.pem k8s@${node_ip}:/etc/kubernetes/cert/ done
重新执行:
curl -s --cacert /etc/kubernetes/cert/ca.pem --cert /etc/kubernetes/cert/admin.pem --key /etc/kubernetes/cert/admin-key.pem https://192.168.1.110:10250/metrics|head
输出:
# 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
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://192.168.1.110:10250/metrics|head
输出:
# 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 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://192.168.1.110:4194/containers/ 可以查看到 cadvisor 的监控页面。
#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;
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 /etc/kubernetes/cert/admin.pem --key /etc/kubernetes/cert/admin-key.pem ${KUBE_APISERVER}/api/v1/nodes/kube-node1/proxy/configz | jq '.kubeletconfig|.kind="KubeletConfiguration"|.apiVersion="kubelet.config.k8s.io/v1beta1"' #{ "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
参考:
https://www.kubernetes.org.cn/3063.html
https://www.kubernetes.org.cn/3096.html
https://github.com/opsnull/follow-me-install-kubernetes-cluster
http://www.imooc.com/article/23355
https://www.docker.com/
kubelet 认证和授权:https://kubernetes.io/docs/reference/command-line-tools-reference/kubelet-authentication-authorization/
编辑:孙小北
本文地址: https://www.xiaowangyun.com/wyblog/detail/?id=235
版权归属: www.xiaowangyun.com 转载时请以链接形式注明出处
0 条评论