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04.etcd集群.md

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tags: etcd

04. 部署 etcd 集群

etcd 是基于 Raft 的分布式 KV 存储系统,由 CoreOS 开发,常用于服务发现、共享配置以及并发控制(如 leader 选举、分布式锁等)。

kubernetes 使用 etcd 集群持久化存储所有 API 对象、运行数据。

本文档介绍部署一个三节点高可用 etcd 集群的步骤:

  • 下载和分发 etcd 二进制文件;
  • 创建 etcd 集群各节点的 x509 证书,用于加密客户端(如 etcdctl) 与 etcd 集群、etcd 集群之间的通信;
  • 创建 etcd 的 systemd unit 文件,配置服务参数;
  • 检查集群工作状态;

etcd 集群节点名称和 IP 如下:

  • zhangjun-k8s-01:172.27.138.251
  • zhangjun-k8s-02:172.27.137.229
  • zhangjun-k8s-03:172.27.138.239

注意:

  1. 如果没有特殊指明,本文档的所有操作均在 zhangjun-k8s-01 节点上执行
  2. flanneld 与本文档安装的 etcd v3.4.x 不兼容,如果要安装 flanneld(本文档使用 calio),则需要将 etcd 降级到 v3.3.x 版本

下载和分发 etcd 二进制文件

到 etcd 的 release 页面 下载最新版本的发布包:

cd /opt/k8s/work
wget https://github.com/coreos/etcd/releases/download/v3.4.3/etcd-v3.4.3-linux-amd64.tar.gz
tar -xvf etcd-v3.4.3-linux-amd64.tar.gz

分发二进制文件到集群所有节点:

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
  do
    echo ">>> ${node_ip}"
    scp etcd-v3.4.3-linux-amd64/etcd* root@${node_ip}:/opt/k8s/bin
    ssh root@${node_ip} "chmod +x /opt/k8s/bin/*"
  done

创建 etcd 证书和私钥

创建证书签名请求:

cd /opt/k8s/work
cat > etcd-csr.json <<EOF
{
  "CN": "etcd",
  "hosts": [
    "127.0.0.1",
    "172.27.138.251",
    "172.27.137.229",
    "172.27.138.239"
  ],
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "ST": "BeiJing",
      "L": "BeiJing",
      "O": "k8s",
      "OU": "opsnull"
    }
  ]
}
EOF
  • hosts:指定授权使用该证书的 etcd 节点 IP 列表,需要将 etcd 集群所有节点 IP 都列在其中

生成证书和私钥:

cd /opt/k8s/work
cfssl gencert -ca=/opt/k8s/work/ca.pem \
    -ca-key=/opt/k8s/work/ca-key.pem \
    -config=/opt/k8s/work/ca-config.json \
    -profile=kubernetes etcd-csr.json | cfssljson -bare etcd
ls etcd*pem

分发生成的证书和私钥到各 etcd 节点:

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
  do
    echo ">>> ${node_ip}"
    ssh root@${node_ip} "mkdir -p /etc/etcd/cert"
    scp etcd*.pem root@${node_ip}:/etc/etcd/cert/
  done

创建 etcd 的 systemd unit 模板文件

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
cat > etcd.service.template <<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=${ETCD_DATA_DIR}
ExecStart=/opt/k8s/bin/etcd \\
  --data-dir=${ETCD_DATA_DIR} \\
  --wal-dir=${ETCD_WAL_DIR} \\
  --name=##NODE_NAME## \\
  --cert-file=/etc/etcd/cert/etcd.pem \\
  --key-file=/etc/etcd/cert/etcd-key.pem \\
  --trusted-ca-file=/etc/kubernetes/cert/ca.pem \\
  --peer-cert-file=/etc/etcd/cert/etcd.pem \\
  --peer-key-file=/etc/etcd/cert/etcd-key.pem \\
  --peer-trusted-ca-file=/etc/kubernetes/cert/ca.pem \\
  --peer-client-cert-auth \\
  --client-cert-auth \\
  --listen-peer-urls=https://##NODE_IP##:2380 \\
  --initial-advertise-peer-urls=https://##NODE_IP##:2380 \\
  --listen-client-urls=https://##NODE_IP##:2379,http://127.0.0.1:2379 \\
  --advertise-client-urls=https://##NODE_IP##:2379 \\
  --initial-cluster-token=etcd-cluster-0 \\
  --initial-cluster=${ETCD_NODES} \\
  --initial-cluster-state=new \\
  --auto-compaction-mode=periodic \\
  --auto-compaction-retention=1 \\
  --max-request-bytes=33554432 \\
  --quota-backend-bytes=6442450944 \\
  --heartbeat-interval=250 \\
  --election-timeout=2000
Restart=on-failure
RestartSec=5
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target
EOF
  • WorkingDirectory--data-dir:指定工作目录和数据目录为 ${ETCD_DATA_DIR},需在启动服务前创建这个目录;
  • --wal-dir:指定 wal 目录,为了提高性能,一般使用 SSD 或者和 --data-dir 不同的磁盘;
  • --name:指定节点名称,当 --initial-cluster-state 值为 new 时,--name 的参数值必须位于 --initial-cluster 列表中;
  • --cert-file--key-file:etcd server 与 client 通信时使用的证书和私钥;
  • --trusted-ca-file:签名 client 证书的 CA 证书,用于验证 client 证书;
  • --peer-cert-file--peer-key-file:etcd 与 peer 通信使用的证书和私钥;
  • --peer-trusted-ca-file:签名 peer 证书的 CA 证书,用于验证 peer 证书;

为各节点创建和分发 etcd systemd unit 文件

替换模板文件中的变量,为各节点创建 systemd unit 文件:

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for (( i=0; i < 3; i++ ))
  do
    sed -e "s/##NODE_NAME##/${NODE_NAMES[i]}/" -e "s/##NODE_IP##/${NODE_IPS[i]}/" etcd.service.template > etcd-${NODE_IPS[i]}.service 
  done
ls *.service
  • NODE_NAMES 和 NODE_IPS 为相同长度的 bash 数组,分别为节点名称和对应的 IP;

分发生成的 systemd unit 文件:

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
  do
    echo ">>> ${node_ip}"
    scp etcd-${node_ip}.service root@${node_ip}:/etc/systemd/system/etcd.service
  done

启动 etcd 服务

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
  do
    echo ">>> ${node_ip}"
    ssh root@${node_ip} "mkdir -p ${ETCD_DATA_DIR} ${ETCD_WAL_DIR}"
    ssh root@${node_ip} "systemctl daemon-reload && systemctl enable etcd && systemctl restart etcd " &
  done
  • 必须先创建 etcd 数据目录和工作目录;
  • etcd 进程首次启动时会等待其它节点的 etcd 加入集群,命令 systemctl start etcd 会卡住一段时间,为正常现象;

检查启动结果

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
  do
    echo ">>> ${node_ip}"
    ssh root@${node_ip} "systemctl status etcd|grep Active"
  done

确保状态为 active (running),否则查看日志,确认原因:

journalctl -u etcd

验证服务状态

部署完 etcd 集群后,在任一 etcd 节点上执行如下命令:

cd /opt/k8s/work
source /opt/k8s/bin/environment.sh
for node_ip in ${NODE_IPS[@]}
  do
    echo ">>> ${node_ip}"
    /opt/k8s/bin/etcdctl \
    --endpoints=https://${node_ip}:2379 \
    --cacert=/etc/kubernetes/cert/ca.pem \
    --cert=/etc/etcd/cert/etcd.pem \
    --key=/etc/etcd/cert/etcd-key.pem endpoint health
  done
  • 3.4.3 版本的 etcd/etcdctl 默认启用了 V3 API,所以执行 etcdctl 命令时不需要再指定环境变量 ETCDCTL_API=3
  • 从 K8S 1.13 开始,不再支持 v2 版本的 etcd;

预期输出:

>>> 172.27.138.251
https://172.27.138.251:2379 is healthy: successfully committed proposal: took = 2.756451ms
>>> 172.27.137.229
https://172.27.137.229:2379 is healthy: successfully committed proposal: took = 2.025018ms
>>> 172.27.138.239
https://172.27.138.239:2379 is healthy: successfully committed proposal: took = 2.335097ms

输出均为 healthy 时表示集群服务正常。

查看当前的 leader

source /opt/k8s/bin/environment.sh
/opt/k8s/bin/etcdctl \
  -w table --cacert=/etc/kubernetes/cert/ca.pem \
  --cert=/etc/etcd/cert/etcd.pem \
  --key=/etc/etcd/cert/etcd-key.pem \
  --endpoints=${ETCD_ENDPOINTS} endpoint status 

输出:

+-----------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+
|          ENDPOINT           |        ID        | VERSION | DB SIZE | IS LEADER | IS LEARNER | RAFT TERM | RAFT INDEX | RAFT APPLIED INDEX | ERRORS |
+-----------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+
| https://172.27.138.251:2379 | 4250b255e93e0076 |   3.4.3 |   20 kB |     false |      false |         2 |          8 |                  8 |        |
| https://172.27.137.229:2379 | b3d912e6166f1213 |   3.4.3 |   20 kB |      true |      false |         2 |          8 |                  8 |        |
| https://172.27.138.239:2379 | 8a4d4a2904de8446 |   3.4.3 |   20 kB |     false |      false |         2 |          8 |                  8 |        |
+-----------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+
  • 可见,当前的 leader 为 172.27.138.229。