137 lines
5.2 KiB
Markdown
137 lines
5.2 KiB
Markdown
# 创建高可用 etcd 集群
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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`test-001.jimmysong.io`、`test-002.jimmysong.io`、`test-003.jimmysong.io`：
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+ test-001.jimmysong.io：172.20.0.113
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+ test-002.jimmysong.io：172.20.0.114
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+ test-003.jimmysong.io：172.20.0.115
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## TLS 认证文件
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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
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``` bash
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cp ca.pem kubernetes-key.pem kubernetes.pem /etc/kubernetes/ssl
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```
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+ 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；
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## 下载二进制文件
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到 `https://github.com/coreos/etcd/releases` 页面下载最新版本的二进制文件
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``` bash
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wget https://github.com/coreos/etcd/releases/download/v3.1.5/etcd-v3.1.5-linux-amd64.tar.gz
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tar -xvf etcd-v3.1.5-linux-amd64.tar.gz
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mv etcd-v3.1.5-linux-amd64/etcd* /usr/local/bin
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```
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或者直接使用yum命令安装：
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```bash
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yum install etcd
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```
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若使用yum安装，默认etcd命令将在`/usr/bin`目录下，注意修改下面`的etcd.service`文件中的启动命令地址为`/usr/bin/etcd`。
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## 创建 etcd 的 systemd unit 文件
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在/usr/lib/systemd/system/目录下创建文件etcd.service，内容如下。注意替换IP地址为你自己的etcd集群的主机IP。
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``` bash
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[Unit]
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Description=Etcd Server
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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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Documentation=https://github.com/coreos
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[Service]
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Type=notify
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WorkingDirectory=/var/lib/etcd/
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EnvironmentFile=-/etc/etcd/etcd.conf
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ExecStart=/usr/local/bin/etcd \
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--name ${ETCD_NAME} \
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--cert-file=/etc/kubernetes/ssl/kubernetes.pem \
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--key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
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--peer-cert-file=/etc/kubernetes/ssl/kubernetes.pem \
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--peer-key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
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--trusted-ca-file=/etc/kubernetes/ssl/ca.pem \
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--peer-trusted-ca-file=/etc/kubernetes/ssl/ca.pem \
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--initial-advertise-peer-urls ${ETCD_INITIAL_ADVERTISE_PEER_URLS} \
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--listen-peer-urls ${ETCD_LISTEN_PEER_URLS} \
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--listen-client-urls ${ETCD_LISTEN_CLIENT_URLS},http://127.0.0.1:2379 \
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--advertise-client-urls ${ETCD_ADVERTISE_CLIENT_URLS} \
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--initial-cluster-token ${ETCD_INITIAL_CLUSTER_TOKEN} \
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--initial-cluster infra1=https://172.20.0.113:2380,infra2=https://172.20.0.114:2380,infra3=https://172.20.0.115:2380 \
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--initial-cluster-state new \
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--data-dir=${ETCD_DATA_DIR}
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Restart=on-failure
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RestartSec=5
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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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+ 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个目录，否则启动服务的时候会报错“Failed at step CHDIR spawning /usr/bin/etcd: No such file or directory”；
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+ 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）；
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+ 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IP**，否则证书校验会出错；
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+ `--initial-cluster-state` 值为 `new` 时，`--name` 的参数值必须位于 `--initial-cluster` 列表中；
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完整 unit 文件见：[etcd.service](../systemd/etcd.service)
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环境变量配置文件`/etc/etcd/etcd.conf`。
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```ini
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# [member]
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ETCD_NAME=infra1
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ETCD_DATA_DIR="/var/lib/etcd"
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ETCD_LISTEN_PEER_URLS="https://172.20.0.113:2380"
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ETCD_LISTEN_CLIENT_URLS="https://172.20.0.113:2379"
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#[cluster]
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ETCD_INITIAL_ADVERTISE_PEER_URLS="https://172.20.0.113:2380"
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ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster"
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ETCD_ADVERTISE_CLIENT_URLS="https://172.20.0.113:2379"
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```
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这是172.20.0.113节点的配置，其他两个etcd节点只要将上面的IP地址改成相应节点的IP地址即可。ETCD_NAME换成对应节点的infra1/2/3。
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## 启动 etcd 服务
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``` bash
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mv etcd.service /usr/lib/systemd/system/
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systemctl daemon-reload
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systemctl enable etcd
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systemctl start etcd
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systemctl status etcd
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```
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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。
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## 验证服务
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在任一 kubernetes master 机器上执行如下命令：
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``` bash
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$ etcdctl \
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--ca-file=/etc/kubernetes/ssl/ca.pem \
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--cert-file=/etc/kubernetes/ssl/kubernetes.pem \
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--key-file=/etc/kubernetes/ssl/kubernetes-key.pem \
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cluster-health
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2017-04-11 15:17:09.082250 I | warning: ignoring ServerName for user-provided CA for backwards compatibility is deprecated
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2017-04-11 15:17:09.083681 I | warning: ignoring ServerName for user-provided CA for backwards compatibility is deprecated
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member 9a2ec640d25672e5 is healthy: got healthy result from https://172.20.0.115:2379
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member bc6f27ae3be34308 is healthy: got healthy result from https://172.20.0.114:2379
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member e5c92ea26c4edba0 is healthy: got healthy result from https://172.20.0.113:2379
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cluster is healthy
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```
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结果最后一行为 `cluster is healthy` 时表示集群服务正常。
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## 更多资料
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关于如何在etcd中查看kubernetes的数据，请参考[使用etcdctl访问kuberentes数据](../guide/using-etcdctl-to-access-kubernetes-data.md)。
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