309 lines
11 KiB
Markdown
309 lines
11 KiB
Markdown
# 部署kubernetes node节点
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kubernetes node 节点包含如下组件：
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+ Flanneld：参考我之前写的文章[Kubernetes基于Flannel的网络配置](http://rootsongjc.github.io/blogs/kubernetes-network-config/)，之前没有配置TLS，现在需要在serivce配置文件中增加TLS配置。
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+ Docker1.12.5：docker的安装很简单，这里也不说了。
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+ kubelet
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+ kube-proxy
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下面着重讲`kubelet`和`kube-proxy`的安装，同时还要将之前安装的flannel集成TLS验证。
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## 目录和文件
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我们再检查一下三个节点上，经过前几步操作生成的配置文件。
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``` bash
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$ ls /etc/kubernetes/ssl
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admin-key.pem admin.pem ca-key.pem ca.pem kube-proxy-key.pem kube-proxy.pem kubernetes-key.pem kubernetes.pem
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$ ls /etc/kubernetes/
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apiserver bootstrap.kubeconfig config controller-manager kubelet kube-proxy.kubeconfig proxy scheduler ssl token.csv
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```
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## 配置Flanneld
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参考我之前写的文章[Kubernetes基于Flannel的网络配置](http://rootsongjc.github.io/blogs/kubernetes-network-config/)，之前没有配置TLS，现在需要在serivce配置文件中增加TLS配置。
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service配置文件`/usr/lib/systemd/system/flanneld.service`。
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```ini
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[Unit]
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Description=Flanneld overlay address etcd agent
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After=network.target
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After=network-online.target
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Wants=network-online.target
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After=etcd.service
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Before=docker.service
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[Service]
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Type=notify
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EnvironmentFile=/etc/sysconfig/flanneld
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EnvironmentFile=-/etc/sysconfig/docker-network
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ExecStart=/usr/bin/flanneld-start $FLANNEL_OPTIONS
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ExecStartPost=/usr/libexec/flannel/mk-docker-opts.sh -k DOCKER_NETWORK_OPTIONS -d /run/flannel/docker
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Restart=on-failure
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[Install]
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WantedBy=multi-user.target
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RequiredBy=docker.service
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```
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`/etc/sysconfig/flanneld`配置文件。
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```ini
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# Flanneld configuration options
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# etcd url location. Point this to the server where etcd runs
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FLANNEL_ETCD_ENDPOINTS="https://172.20.0.113:2379,https://172.20.0.114:2379,https://172.20.0.115:2379"
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# etcd config key. This is the configuration key that flannel queries
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# For address range assignment
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FLANNEL_ETCD_PREFIX="/kube-centos/network"
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# Any additional options that you want to pass
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FLANNEL_OPTIONS="-etcd-cafile=/etc/kubernetes/ssl/ca.pem -etcd-certfile=/etc/kubernetes/ssl/kubernetes.pem -etcd-keyfile=/etc/kubernetes/ssl/kubernetes-key.pem"
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```
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在FLANNEL_OPTIONS中增加TLS的配置。
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## 安装和配置 kubelet
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kubelet 启动时向 kube-apiserver 发送 TLS bootstrapping 请求，需要先将 bootstrap token 文件中的 kubelet-bootstrap 用户赋予 system:node-bootstrapper cluster 角色(role)，
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然后 kubelet 才能有权限创建认证请求(certificate signing requests)：
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``` bash
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$ cd /etc/kubernetes
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$ kubectl create clusterrolebinding kubelet-bootstrap \
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--clusterrole=system:node-bootstrapper \
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--user=kubelet-bootstrap
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```
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+ `--user=kubelet-bootstrap` 是在 `/etc/kubernetes/token.csv` 文件中指定的用户名，同时也写入了 `/etc/kubernetes/bootstrap.kubeconfig` 文件；
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### 下载最新的 kubelet 和 kube-proxy 二进制文件
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``` bash
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$ wget https://dl.k8s.io/v1.6.0/kubernetes-server-linux-amd64.tar.gz
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$ tar -xzvf kubernetes-server-linux-amd64.tar.gz
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$ cd kubernetes
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$ tar -xzvf kubernetes-src.tar.gz
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$ cp -r ./server/bin/{kube-proxy,kubelet} /usr/bin/
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```
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### 创建 kubelet 的service配置文件
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文件位置`/usr/lib/systemd/system/kubelet.serivce`。
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```ini
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[Unit]
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Description=Kubernetes Kubelet Server
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Documentation=https://github.com/GoogleCloudPlatform/kubernetes
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After=docker.service
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Requires=docker.service
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[Service]
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WorkingDirectory=/var/lib/kubelet
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EnvironmentFile=-/etc/kubernetes/config
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EnvironmentFile=-/etc/kubernetes/kubelet
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ExecStart=/usr/bin/kubelet \
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$KUBE_LOGTOSTDERR \
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$KUBE_LOG_LEVEL \
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$KUBELET_API_SERVER \
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$KUBELET_ADDRESS \
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$KUBELET_PORT \
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$KUBELET_HOSTNAME \
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$KUBE_ALLOW_PRIV \
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$KUBELET_POD_INFRA_CONTAINER \
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$KUBELET_ARGS
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Restart=on-failure
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[Install]
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WantedBy=multi-user.target
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```
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kubelet的配置文件`/etc/kubernetes/kubelet`。其中的IP地址更改为你的每台node节点的IP地址。
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``` bash
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###
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## kubernetes kubelet (minion) config
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#
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## The address for the info server to serve on (set to 0.0.0.0 or "" for all interfaces)
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KUBELET_ADDRESS="--address=172.20.0.113"
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#
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## The port for the info server to serve on
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#KUBELET_PORT="--port=10250"
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#
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## You may leave this blank to use the actual hostname
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KUBELET_HOSTNAME="--hostname-override=172.20.0.113"
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#
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## location of the api-server
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KUBELET_API_SERVER="--api-servers=http://172.20.0.113:8080"
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#
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## pod infrastructure container
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KUBELET_POD_INFRA_CONTAINER="--pod-infra-container-image=sz-pg-oam-docker-hub-001.tendcloud.com/library/pod-infrastructure:rhel7"
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#
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## Add your own!
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KUBELET_ARGS="--cgroup-driver=systemd --cluster-dns=10.254.0.2 --experimental-bootstrap-kubeconfig=/etc/kubernetes/bootstrap.kubeconfig --kubeconfig=/etc/kubernetes/kubelet.kubeconfig --require-kubeconfig --cert-dir=/etc/kubernetes/ssl --cluster-domain=cluster.local. --hairpin-mode promiscuous-bridge --serialize-image-pulls=false"
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```
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+ `--address` 不能设置为 `127.0.0.1`，否则后续 Pods 访问 kubelet 的 API 接口时会失败，因为 Pods 访问的 `127.0.0.1` 指向自己而不是 kubelet；
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+ 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；
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+ `--experimental-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；
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+ 管理员通过了 CSR 请求后，kubelet 自动在 `--cert-dir` 目录创建证书和私钥文件(`kubelet-client.crt` 和 `kubelet-client.key`)，然后写入 `--kubeconfig` 文件；
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+ 建议在 `--kubeconfig` 配置文件中指定 `kube-apiserver` 地址，如果未指定 `--api-servers` 选项，则必须指定 `--require-kubeconfig` 选项后才从配置文件中读取 kube-apiserver 的地址，否则 kubelet 启动后将找不到 kube-apiserver (日志中提示未找到 API Server），`kubectl get nodes` 不会返回对应的 Node 信息;
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+ `--cluster-dns` 指定 kubedns 的 Service IP(可以先分配，后续创建 kubedns 服务时指定该 IP)，`--cluster-domain` 指定域名后缀，这两个参数同时指定后才会生效；
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完整 unit 见 [kubelet.service](./systemd/kubelet.service)
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### 启动kublet
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``` bash
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$ systemctl daemon-reload
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$ systemctl enable kubelet
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$ systemctl start kubelet
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$ systemctl status kubelet
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```
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### 通过 kublet 的 TLS 证书请求
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kubelet 首次启动时向 kube-apiserver 发送证书签名请求，必须通过后 kubernetes 系统才会将该 Node 加入到集群。
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查看未授权的 CSR 请求
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``` bash
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$ kubectl get csr
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NAME AGE REQUESTOR CONDITION
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csr-2b308 4m kubelet-bootstrap Pending
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$ kubectl get nodes
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No resources found.
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```
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通过 CSR 请求
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``` bash
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$ kubectl certificate approve csr-2b308
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certificatesigningrequest "csr-2b308" approved
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$ kubectl get nodes
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NAME STATUS AGE VERSION
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10.64.3.7 Ready 49m v1.6.1
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```
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自动生成了 kubelet kubeconfig 文件和公私钥
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``` bash
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$ ls -l /etc/kubernetes/kubelet.kubeconfig
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-rw------- 1 root root 2284 Apr 7 02:07 /etc/kubernetes/kubelet.kubeconfig
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$ ls -l /etc/kubernetes/ssl/kubelet*
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-rw-r--r-- 1 root root 1046 Apr 7 02:07 /etc/kubernetes/ssl/kubelet-client.crt
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-rw------- 1 root root 227 Apr 7 02:04 /etc/kubernetes/ssl/kubelet-client.key
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-rw-r--r-- 1 root root 1103 Apr 7 02:07 /etc/kubernetes/ssl/kubelet.crt
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-rw------- 1 root root 1675 Apr 7 02:07 /etc/kubernetes/ssl/kubelet.key
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```
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## 配置 kube-proxy
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**创建 kube-proxy 的service配置文件**
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文件路径`/usr/lib/systemd/system/kube-proxy.service`。
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```ini
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[Unit]
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Description=Kubernetes Kube-Proxy Server
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Documentation=https://github.com/GoogleCloudPlatform/kubernetes
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After=network.target
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[Service]
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EnvironmentFile=-/etc/kubernetes/config
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EnvironmentFile=-/etc/kubernetes/proxy
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ExecStart=/usr/bin/kube-proxy \
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$KUBE_LOGTOSTDERR \
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$KUBE_LOG_LEVEL \
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$KUBE_MASTER \
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$KUBE_PROXY_ARGS
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Restart=on-failure
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LimitNOFILE=65536
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[Install]
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WantedBy=multi-user.target
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```
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kube-proxy配置文件`/etc/kubernetes/proxy`。
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``` bash
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###
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# kubernetes proxy config
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# default config should be adequate
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# Add your own!
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KUBE_PROXY_ARGS="--bind-address=172.20.0.113 --hostname-override=172.20.0.113 --kubeconfig=/etc/kubernetes/kube-proxy.kubeconfig --cluster-cidr=10.254.0.0/16"
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```
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+ `--hostname-override` 参数值必须与 kubelet 的值一致，否则 kube-proxy 启动后会找不到该 Node，从而不会创建任何 iptables 规则；
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+ kube-proxy 根据 `--cluster-cidr` 判断集群内部和外部流量，指定 `--cluster-cidr` 或 `--masquerade-all` 选项后 kube-proxy 才会对访问 Service IP 的请求做 SNAT；
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+ `--kubeconfig` 指定的配置文件嵌入了 kube-apiserver 的地址、用户名、证书、秘钥等请求和认证信息；
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+ 预定义的 RoleBinding `cluster-admin` 将User `system:kube-proxy` 与 Role `system:node-proxier` 绑定，该 Role 授予了调用 `kube-apiserver` Proxy 相关 API 的权限；
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完整 unit 见 [kube-proxy.service](./systemd/kube-proxy.service)
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### 启动 kube-proxy
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``` bash
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$ systemctl daemon-reload
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$ systemctl enable kube-proxy
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$ systemctl start kube-proxy
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$ systemctl status kube-proxy
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```
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## 验证测试
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我们创建一个niginx的service试一下集群是否可用。
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```bash
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$ kubectl run nginx --replicas=2 --labels="run=load-balancer-example" --image=sz-pg-oam-docker-hub-001.tendcloud.com/library/nginx:1.9 --port=80
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deployment "nginx" created
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$ kubectl expose deployment nginx --type=NodePort --name=example-service
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service "example-service" exposed
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$ kubectl describe svc example-service
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Name: example-service
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Namespace: default
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Labels: run=load-balancer-example
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Annotations: <none>
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Selector: run=load-balancer-example
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Type: NodePort
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IP: 10.254.62.207
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Port: <unset> 80/TCP
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NodePort: <unset> 32724/TCP
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Endpoints: 172.30.60.2:80,172.30.94.2:80
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Session Affinity: None
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Events: <none>
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$ curl "10.254.62.207:80"
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<!DOCTYPE html>
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<html>
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<head>
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<title>Welcome to nginx!</title>
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<style>
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body {
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width: 35em;
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margin: 0 auto;
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font-family: Tahoma, Verdana, Arial, sans-serif;
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}
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</style>
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</head>
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<body>
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<h1>Welcome to nginx!</h1>
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<p>If you see this page, the nginx web server is successfully installed and
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working. Further configuration is required.</p>
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<p>For online documentation and support please refer to
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<a href="http://nginx.org/">nginx.org</a>.<br/>
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Commercial support is available at
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<a href="http://nginx.com/">nginx.com</a>.</p>
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<p><em>Thank you for using nginx.</em></p>
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</body>
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</html>
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```
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访问`172.20.0.113:32724`或`172.20.0.114:32724`或者`172.20.0.115:32724`都可以得到nginx的页面。
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