Etcd v3备份与恢复

ETCD 简介

ETCD 是用于共享配置和服务发现的分布式，一致性的KV存储系统。ETCD是CoreOS公司发起的一个开源项目，授权协议为Apache。

ETCD 使用场景

ETCD 有很多使用场景，包括但不限于：

配置管理
服务注册于发现
选主
应用调度
分布式队列
分布式锁

ETCD 存储 k8s 所有数据信息

ETCD 是k8s集群极为重要的一块服务，存储了集群所有的数据信息。同理，如果发生灾难或者 etcd 的数据丢失，都会影响集群数据的恢复。所以，本文重点讲如何备份和恢复数据。

ETCD 一些查询操作

查看集群状态

$ ETCDCTL_API=3 etcdctl --cacert=/opt/kubernetes/ssl/ca.pem --cert=/opt/kubernetes/ssl/server.pem --key=/opt/kubernetes/ssl/server-key.pem --endpoints=https://192.168.1.36:2379,https://192.168.1.37:2379,https://192.168.1.38:2379 endpoint health
https://192.168.1.36:2379 is healthy: successfully committed proposal: took = 1.698385mshttps://192.168.1.37:2379 is healthy: successfully committed proposal: took = 1.577913mshttps://192.168.1.38:2379 is healthy: successfully committed proposal: took = 5.616079ms

获取某个 key 信息

$ ETCDCTL_API=3 etcdctl --cacert=/opt/kubernetes/ssl/ca.pem --cert=/opt/kubernetes/ssl/server.pem --key=/opt/kubernetes/ssl/server-key.pem --endpoints=https://192.168.1.36:2379,https://192.168.1.37:2379,https://192.168.1.38:2379 get /registry/apiregistration.k8s.io/apiservices/v1.apps

获取 etcd 版本信息

$ ETCDCTL_API=3 etcdctl --cacert=/opt/kubernetes/ssl/ca.pem --cert=/opt/kubernetes/ssl/server.pem --key=/opt/kubernetes/ssl/server-key.pem --endpoints=https://192.168.1.36:2379,https://192.168.1.37:2379,https://192.168.1.38:2379 version

获取 ETCD 所有的 key

$ ETCDCTL_API=3 etcdctl --cacert=/opt/kubernetes/ssl/ca.pem --cert=/opt/kubernetes/ssl/server.pem --key=/opt/kubernetes/ssl/server-key.pem --endpoints=https://192.168.1.36:2379,https://192.168.1.37:2379,https://192.168.1.38:2379 get / --prefix --keys-only

环境

k8s-master1	192.168.1.36
k8s-master2	192.168.1.37
k8s-master3	192.168.1.38

ETCD version 3.2.12
Kubernetes version v1.15.6 二进制安装

备份

注意：ETCD 不同的版本的 etcdctl 命令不一样，但大致差不多，本文备份使用 napshot save , 每次备份一个节点就行。

命令备份（k8s-master1 机器上备份）：

$ ETCDCTL_API=3 etcdctl --cacert=/opt/kubernetes/ssl/ca.pem --cert=/opt/kubernetes/ssl/server.pem --key=/opt/kubernetes/ssl/server-key.pem --endpoints=https://192.168.1.36:2379 snapshot save /data/etcd_backup_dir/etcd-snapshot-`date +%Y%m%d`.db

备份脚本（k8s-master1 机器上备份）：

#!/usr/bin/env bash
date;
CACERT="/opt/kubernetes/ssl/ca.pem"CERT="/opt/kubernetes/ssl/server.pem"EKY="/opt/kubernetes/ssl/server-key.pem"ENDPOINTS="192.168.1.36:2379"
ETCDCTL_API=3 etcdctl \--cacert="${CACERT}" --cert="${CERT}" --key="${EKY}" \--endpoints=${ENDPOINTS} \snapshot save /data/etcd_backup_dir/etcd-snapshot-`date +%Y%m%d`.db
# 备份保留30天find /data/etcd_backup_dir/ -name *.db -mtime +30 -exec rm -f {} \;

恢复

准备工作

停止所有 Master 上 kube-apiserver 服务

$ systemctl stop kube-apiserver
# 确认 kube-apiserver 服务是否停止$ ps -ef | grep kube-apiserver

停止集群中所有 ETCD 服务
```
$ systemctl stop etcd
```

移除所有 ETCD 存储目录下数据

$ mv /var/lib/etcd/default.etcd /var/lib/etcd/default.etcd.bak

拷贝 ETCD 备份快照

# 从 k8s-master1 机器上拷贝备份$ scp /data/etcd_backup_dir/etcd-snapshot-20191222.db root@k8s-master2:/data/etcd_backup_dir/$ scp /data/etcd_backup_dir/etcd-snapshot-20191222.db root@k8s-master3:/data/etcd_backup_dir/

恢复备份

# k8s-master1 机器上操作$ ETCDCTL_API=3 etcdctl snapshot restore /data/etcd_backup_dir/etcd-snapshot-20191222.db \  --name etcd-0 \  --initial-cluster "etcd-0=https://192.168.1.36:2380,etcd-1=https://192.168.1.37:2380,etcd-2=https://192.168.1.38:2380" \  --initial-cluster-token etcd-cluster \  --initial-advertise-peer-urls https://192.168.1.36:2380 \  --data-dir=/var/lib/etcd/default.etcd# k8s-master2 机器上操作$ ETCDCTL_API=3 etcdctl snapshot restore /data/etcd_backup_dir/etcd-snapshot-20191222.db \  --name etcd-1 \  --initial-cluster "etcd-0=https://192.168.1.36:2380,etcd-1=https://192.168.1.37:2380,etcd-2=https://192.168.1.38:2380"  \  --initial-cluster-token etcd-cluster \  --initial-advertise-peer-urls https://192.168.1.37:2380 \  --data-dir=/var/lib/etcd/default.etcd# k8s-master3 机器上操作$ ETCDCTL_API=3 etcdctl snapshot restore /data/etcd_backup_dir/etcd-snapshot-20191222.db \  --name etcd-2 \  --initial-cluster "etcd-0=https://192.168.1.36:2380,etcd-1=https://192.168.1.37:2380,etcd-2=https://192.168.1.38:2380"  \  --initial-cluster-token etcd-cluster \  --initial-advertise-peer-urls https://192.168.1.38:2380 \  --data-dir=/var/lib/etcd/default.etcd

上面三台 ETCD 都恢复完成后，依次登陆三台机器启动 ETCD

$ systemctl start etcd

三台 ETCD 启动完成，检查 ETCD 集群状态

$ ETCDCTL_API=3 etcdctl --cacert=/opt/kubernetes/ssl/ca.pem --cert=/opt/kubernetes/ssl/server.pem --key=/opt/kubernetes/ssl/server-key.pem --endpoints=https://192.168.1.36:2379,https://192.168.1.37:2379,https://192.168.1.38:2379 endpoint health

三台 ETCD 全部健康，分别到每台 Master 启动 kube-apiserver

$ systemctl start kube-apiserver

检查 Kubernetes 集群是否恢复正常

$ kubectl get cs

总结

Kubernetes 集群备份主要是备份 ETCD 集群。而恢复时，主要考虑恢复整个顺序：

停止kube-apiserver --> 停止ETCD --> 恢复数据 --> 启动ETCD --> 启动kube-apiserve