Kubernetes安装之etcd高可用配置

西山俯瞰北京夜景

(题图:北京夜景@西山)

前言

这是和我一步步部署kubernetes集群项目((fork自opsnull))中的一篇文章,下文是结合我之前部署kubernetes的过程产生的kuberentes环境,生成kubeconfig文件的过程。

创建高可用 etcd 集群

kuberntes 系统使用 etcd 存储所有数据,本文档介绍部署一个三节点高可用 etcd 集群的步骤,这三个节点复用 kubernetes master 机器,分别命名为sz-pg-oam-docker-test-001.tendcloud.comsz-pg-oam-docker-test-002.tendcloud.comsz-pg-oam-docker-test-003.tendcloud.com

  • sz-pg-oam-docker-test-001.tendcloud.com:172.20.0.113
  • sz-pg-oam-docker-test-002.tendcloud.com:172.20.0.114
  • sz-pg-oam-docker-test-003.tendcloud.com:172.20.0.115

TLS 认证文件

需要为 etcd 集群创建加密通信的 TLS 证书,这里复用以前创建的 kubernetes 证书

$ cp ca.pem kubernetes-key.pem kubernetes.pem /etc/kubernetes/ssl
  • kubernetes 证书的 hosts 字段列表中包含上面三台机器的 IP,否则后续证书校验会失败;

下载二进制文件

https://github.com/coreos/etcd/releases 页面下载最新版本的二进制文件

$ https://github.com/coreos/etcd/releases/download/v3.1.5/etcd-v3.1.5-linux-amd64.tar.gz
$ tar -xvf etcd-v3.1.4-linux-amd64.tar.gz
$ sudo mv etcd-v3.1.4-linux-amd64/etcd* /root/local/bin

创建 etcd 的 systemd unit 文件

注意替换 ETCD_NAMEINTERNAL_IP 变量的值;

$ export ETCD_NAME=sz-pg-oam-docker-test-001.tendcloud.com
$ export INTERNAL_IP=172.20.0.113
$ sudo mkdir -p /var/lib/etcd /var/lib/etcd
$ cat > etcd.service <<EOF
[Unit]
Description=Etcd Server
After=network.target
After=network-online.target
Wants=network-online.target
Documentation=https://github.com/coreos

[Service]
Type=notify
WorkingDirectory=/var/lib/etcd/
EnvironmentFile=-/etc/etcd/etcd.conf
ExecStart=/root/local/bin/etcd \\
  --name ${ETCD_NAME} \\
  --cert-file=/etc/kubernetes/ssl/kubernetes.pem \\
  --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \\
  --peer-cert-file=/etc/kubernetes/ssl/kubernetes.pem \\
  --peer-key-file=/etc/kubernetes/ssl/kubernetes-key.pem \\
  --trusted-ca-file=/etc/kubernetes/ssl/ca.pem \\
  --peer-trusted-ca-file=/etc/kubernetes/ssl/ca.pem \\
  --initial-advertise-peer-urls https://${INTERNAL_IP}:2380 \\
  --listen-peer-urls https://${INTERNAL_IP}:2380 \\
  --listen-client-urls https://${INTERNAL_IP}:2379,https://127.0.0.1:2379 \\
  --advertise-client-urls https://${INTERNAL_IP}:2379 \\
  --initial-cluster-token etcd-cluster-0 \\
  --initial-cluster sz-pg-oam-docker-test-001.tendcloud.com=https://172.20.0.113:2380,sz-pg-oam-docker-test-002.tendcloud.com=https://172.20.0.114:2380,sz-pg-oam-docker-test-003.tendcloud.com=https://172.20.0.115:2380 \\
  --initial-cluster-state new \\
  --data-dir=/var/lib/etcd
Restart=on-failure
RestartSec=5
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target
EOF
  • 指定 etcd 的工作目录为 /var/lib/etcd,数据目录为 /var/lib/etcd,需在启动服务前创建这两个目录;
  • 为了保证通信安全,需要指定 etcd 的公私钥(cert-file和key-file)、Peers 通信的公私钥和 CA 证书(peer-cert-file、peer-key-file、peer-trusted-ca-file)、客户端的CA证书(trusted-ca-file);
  • 创建 kubernetes.pem 证书时使用的 kubernetes-csr.json 文件的 hosts 字段包含所有 etcd 节点的 INTERNAL_IP,否则证书校验会出错;
  • --initial-cluster-state 值为 new 时,--name 的参数值必须位于 --initial-cluster 列表中;

完整 unit 文件见:etcd.service

启动 etcd 服务

$ sudo mv etcd.service /etc/systemd/system/
$ sudo systemctl daemon-reload
$ sudo systemctl enable etcd
$ sudo systemctl start etcd
$ systemctl status etcd

在所有的 kubernetes master 节点重复上面的步骤,直到所有机器的 etcd 服务都已启动。

验证服务

在任一 kubernetes master 机器上执行如下命令:

$ etcdctl \
  --ca-file=/etc/kubernetes/ssl/ca.pem \
  --cert-file=/etc/kubernetes/ssl/kubernetes.pem \
  --key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
  cluster-health
2017-04-11 15:17:09.082250 I | warning: ignoring ServerName for user-provided CA for backwards compatibility is deprecated
2017-04-11 15:17:09.083681 I | warning: ignoring ServerName for user-provided CA for backwards compatibility is deprecated
member 9a2ec640d25672e5 is healthy: got healthy result from https://172.20.0.115:2379
member bc6f27ae3be34308 is healthy: got healthy result from https://172.20.0.114:2379
member e5c92ea26c4edba0 is healthy: got healthy result from https://172.20.0.113:2379
cluster is healthy

结果最后一行为 cluster is healthy 时表示集群服务正常。