Kubernetes 集群灾备环境部署的问题，这篇文章全告诉你了~
etcd 是 kubernetes 集群极为重要的一块服务，存储了kubernetes集群所有的数据信息，如 Namespace、Pod、Service、路由等状态信息。如果 etcd 集群-发生灾难或者 etcd 集群数据丢失，都会影响k8s集群数据的恢复。因此，通过备份 etcd 数据来实现kubernetes 集群的灾备环境十分重要。
一、etcd集群备份
etcd 不同版本的 etcdctl 命令不一样，但大致差不多，这里备份使用 napshot save 进行快照备份。
需要注意几点：
备份操作在 etcd 集群的其中一个节点执行就可以。
这里使用的是 etcd v3 的 api，因为从 k8s 1.13 开始，k8s 不再支持 v2 版本的 etcd，即 k8s 的集群数据都存在了 v3 版本的 etcd 中。故备份的数据也只备份了使用 v3 添加的 etcd 数据，v2 添加的 etcd 数据是没有做备份的。
本案例使用的是二进制部署的 k8s v1.18.6 + Calico 容器环境（下面命令中的”ETCDCTL_API=3 etcdctl” 等同于 “etcdctl”）
1）开始备份之前，先来查看下etcd数据
etcd 数据目录[root@k8s-master01 ~]# cat /opt/k8s/bin/environment.sh |grep "ETCD_DATA_DIR="export ETCD_DATA_DIR="/data/k8s/etcd/data"
etcd WAL 目录[root@k8s-master01 ~]# cat /opt/k8s/bin/environment.sh |grep "ETCD_WAL_DIR="export ETCD_WAL_DIR="/data/k8s/etcd/wal"
[root@k8s-master01 ~]# ls /data/k8s/etcd/data/member[root@k8s-master01 ~]# ls /data/k8s/etcd/data/member/snap[root@k8s-master01 ~]# ls /data/k8s/etcd/wal/0000000000000000-0000000000000000.wal .tmp
2）执行etcd集群数据备份
在etcd集群的其中一个节点执行备份操作，然后将备份文件拷贝到其他节点上。
先在etcd集群的每个节点上创建备份目录
# mkdir -p /data/etcd_backup_dir
在 etcd 集群其中个一个节点（这里在k8s-master01）上执行备份：
[root@k8s-master01 ~]# ETCDCTL_API=3 etcdctl --cacert=/etc/kubernetes/cert/ca.pem --cert=/etc/etcd/cert/etcd.pem --key=/etc/etcd/cert/etcd-key.pem --endpoints=https://172.16.60.231:2379 snapshot save /data/etcd_backup_dir/etcd-snapshot-`date +%Y%m%d`.db
将备份文件拷贝到其他的 etcd 节点
[root@k8s-master01 ~]# rsync -e "ssh -p22" -avpgolr /data/etcd_backup_dir/etcd-snapshot-20200820.db root@k8s-master02:/data/etcd_backup_dir/[root@k8s-master01 ~]# rsync -e "ssh -p22" -avpgolr /data/etcd_backup_dir/etcd-snapshot-20200820.db root@k8s-master03:/data/etcd_backup_dir/
可以将上面 k8s-master01 节点的 etcd 备份命令放在脚本里，结合 crontab 进行定时备份：
[root@k8s-master01 ~]# cat /data/etcd_backup_dir/etcd_backup.sh
date;CACERT="/etc/kubernetes/cert/ca.pem"CERT="/etc/etcd/cert/etcd.pem"EKY="/etc/etcd/cert/etcd-key.pem"ENDPOINTS="172.16.60.231:2379"
ETCDCTL_API=3 /opt/k8s/bin/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 {} \;
# 同步到其他两个etcd节点/bin/rsync -e "ssh -p5522" -avpgolr --delete /data/etcd_backup_dir/ root@k8s-master02:/data/etcd_backup_dir//bin/rsync -e "ssh -p5522" -avpgolr --delete /data/etcd_backup_dir/ root@k8s-master03:/data/etcd_backup_dir/设置 crontab 定时备份任务，每天凌晨5点执行备份：
[root@k8s-master01 ~]# chmod 755 /data/etcd_backup_dir/etcd_backup.sh[root@k8s-master01 ~]# crontab -l#etcd集群数据备份 5 * * * /bin/bash -x /data/etcd_backup_dir/etcd_backup.sh > /dev/null 2>&1
二、etcd 集群恢复
etcd 集群备份操作只需要在其中的一个etcd节点上完成，然后将备份文件拷贝到其他节点。
但etcd集群恢复操作必须要所有的etcd节点上完成！
1）模拟 etcd 集群数据丢失
删除三个etcd集群节点的data数据 (或者直接删除data目录)
# rm -rf /data/k8s/etcd/data/*
查看 k8s 集群状态：
[root@k8s-master01 ~]# kubectl get csNAME STATUS MESSAGE ERRORetcd-2 Unhealthy Get https://172.16.60.233:2379/health: dial tcp 172.16.60.233:2379: connect: connection refusedetcd-1 Unhealthy Get https://172.16.60.232:2379/health: dial tcp 172.16.60.232:2379: connect: connection refusedetcd- Unhealthy Get https://172.16.60.231:2379/health: dial tcp 172.16.60.231:2379: connect: connection refusedscheduler Healthy okcontroller-manager Healthy ok
由于此时 etcd 集群的三个节点服务还在，过一会儿查看集群状态恢复正常：
[root@k8s-master01 ~]# kubectl get csNAME STATUS MESSAGE ERRORcontroller-manager Healthy okscheduler Healthy oketcd- Healthy {"health":"true"}etcd-2 Healthy {"health":"true"}etcd-1 Healthy {"health":"true"}
[root@k8s-master01 ~]# ETCDCTL_API=3 etcdctl --endpoints="https://172.16.60.231:2379,https://172.16.60.232:2379,https://172.16.60.233:2379" --cert=/etc/etcd/cert/etcd.pem --key=/etc/etcd/cert/etcd-key.pem --cacert=/etc/kubernetes/cert/ca.pem endpoint healthhttps://172.16.60.231:2379 is healthy: successfully committed proposal: took = 9.918673mshttps://172.16.60.233:2379 is healthy: successfully committed proposal: took = 10.985279mshttps://172.16.60.232:2379 is healthy: successfully committed proposal: took = 13.422545ms
[root@k8s-master01 ~]# ETCDCTL_API=3 etcdctl --endpoints="https://172.16.60.231:2379,https://172.16.60.232:2379,https://172.16.60.233:2379" --cert=/etc/etcd/cert/etcd.pem --key=/etc/etcd/cert/etcd-key.pem --cacert=/etc/kubernetes/cert/ca.pem member list --write-out=table+------------------+---------+------------+----------------------------+----------------------------+------------+| ID | STATUS | NAME | PEER ADDRS | CLIENT ADDRS | IS LEARNER |+------------------+---------+------------+----------------------------+----------------------------+------------+| 1d1d7edbba38c293 | started | k8s-etcd03 | https://172.16.60.233:2380 | https://172.16.60.233:2379 | false || 4c0cfad24e92e45f | started | k8s-etcd02 | https://172.16.60.232:2380 | https://172.16.60.232:2379 | false || 79cf4f0a8c3da54b | started | k8s-etcd01 | https://172.16.60.231:2380 | https://172.16.60.231:2379 | false |+------------------+---------+------------+----------------------------+----------------------------+------------+
如上发现，etcd集群三个节点的leader都是false，即没有选主。此时需要重启三个节点的etcd服务：
# systemctl restart etcd
重启后，再次查看发现etcd集群已经选主成功，集群状态正
[root@k8s-master01 ~]# ETCDCTL_API=3 etcdctl -w table --cacert=/etc/kubernetes/cert/ca.pem --cert=/etc/etcd/cert/etcd.pem --key=/etc/etcd/cert/etcd-key.pem --endpoints="https://172.16.60.231:2379,https://172.16.60.232:2379,https://172.16.60.233:2379" endpoint status+----------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+| ENDPOINT | ID | VERSION | DB SIZE | IS LEADER | IS LEARNER | RAFT TERM | RAFT INDEX | RAFT APPLIED INDEX | ERRORS |+----------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+| https://172.16.60.231:2379 | 79cf4f0a8c3da54b | 3.4.9 | 1.6 MB | true | false | 5 | 24658 | 24658 | || https://172.16.60.232:2379 | 4c0cfad24e92e45f | 3.4.9 | 1.6 MB | false | false | 5 | 24658 | 24658 | || https://172.16.60.233:2379 | 1d1d7edbba38c293 | 3.4.9 | 1.7 MB | false | false | 5 | 24658 | 24658 | |+----------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+
但是，k8s集群数据其实已经丢失了。namespace命名空间下的pod等资源都没有了。此时就需要通过etcd集群备份文件来恢复，即通过上面的etcd集群快照文件恢复。
[root@k8s-master01 ~]# kubectl get nsNAME STATUS AGEdefault Active 9m47skube-node-lease Active 9m39skube-public Active 9m39skube-system Active 9m47s[root@k8s-master01 ~]# kubectl get pods -n kube-systemNo resources found in kube-system namespace.[root@k8s-master01 ~]# kubectl get pods --all-namespacesNo resources found
2）etcd 集群数据恢复，即 kubernetes 集群数据恢复
在 etcd 数据恢复之前，先依次关闭所有 master 节点的 kube-aposerver 服务，所有etcd 节点的 etcd 服务：
# systemctl stop kube-apiserver# systemctl stop etcd
特别注意：在进行 etcd 集群数据恢复之前，一定要先将所有 etcd 节点的 data 和 wal 旧工作目录删掉，这里指的是/data/k8s/etcd/data文件夹跟/data/k8s/etcd/wal文件夹，可能会导致恢复失败（恢复命令执行时报错数据目录已存在）。
# rm -rf /data/k8s/etcd/data && rm -rf /data/k8s/etcd/wal
在每个etcd节点执行恢复操作：
172.16.60.231节点-------------------------------------------------------ETCDCTL_API=3 etcdctl \--name=k8s-etcd01 \--endpoints="https://172.16.60.231:2379" \--cert=/etc/etcd/cert/etcd.pem \--key=/etc/etcd/cert/etcd-key.pem \--cacert=/etc/kubernetes/cert/ca.pem \--initial-cluster-token=etcd-cluster- \--initial-advertise-peer-urls=https://172.16.60.231:2380 \--initial-cluster=k8s-etcd01=https://172.16.60.231:2380,k8s-etcd02=https://172.16.60.232:2380,k8s-etcd03=https://192.168.137.233:2380 \--data-dir=/data/k8s/etcd/data \--wal-dir=/data/k8s/etcd/wal \snapshot restore /data/etcd_backup_dir/etcd-snapshot-20200820.db
172.16.60.232节点-------------------------------------------------------ETCDCTL_API=3 etcdctl \--name=k8s-etcd02 \--endpoints="https://172.16.60.232:2379" \--cert=/etc/etcd/cert/etcd.pem \--key=/etc/etcd/cert/etcd-key.pem \--cacert=/etc/kubernetes/cert/ca.pem \--initial-cluster-token=etcd-cluster- \--initial-advertise-peer-urls=https://172.16.60.232:2380 \--initial-cluster=k8s-etcd01=https://172.16.60.231:2380,k8s-etcd02=https://172.16.60.232:2380,k8s-etcd03=https://192.168.137.233:2380 \--data-dir=/data/k8s/etcd/data \--wal-dir=/data/k8s/etcd/wal \snapshot restore /data/etcd_backup_dir/etcd-snapshot-20200820.db
192.168.137.233节点-------------------------------------------------------ETCDCTL_API=3 etcdctl \--name=k8s-etcd03 \--endpoints="https://192.168.137.233:2379" \--cert=/etc/etcd/cert/etcd.pem \--key=/etc/etcd/cert/etcd-key.pem \--cacert=/etc/kubernetes/cert/ca.pem \--initial-cluster-token=etcd-cluster- \--initial-advertise-peer-urls=https://192.168.137.233:2380 \--initial-cluster=k8s-etcd01=https://172.16.60.231:2380,k8s-etcd02=https://172.16.60.232:2380,k8s-etcd03=https://192.168.137.233:2380 \--data-dir=/data/k8s/etcd/data \--wal-dir=/data/k8s/etcd/wal \snapshot restore /data/etcd_backup_dir/etcd-snapshot-20200820.db
依次启动所有etcd节点的etcd服务：
# systemctl start etcd# systemctl status etcd
检查 ETCD 集群状态（如下，发现etcd集群里已经成功选主了）
[root@k8s-master01 ~]# ETCDCTL_API=3 etcdctl --endpoints="https://172.16.60.231:2379,https://172.16.60.232:2379,https://172.16.60.233:2379" --cert=/etc/etcd/cert/etcd.pem --key=/etc/etcd/cert/etcd-key.pem --cacert=/etc/kubernetes/cert/ca.pem endpoint healthhttps://172.16.60.232:2379 is healthy: successfully committed proposal: took = 12.837393mshttps://172.16.60.233:2379 is healthy: successfully committed proposal: took = 13.306671mshttps://172.16.60.231:2379 is healthy: successfully committed proposal: took = 13.602805ms
[root@k8s-master01 ~]# ETCDCTL_API=3 etcdctl -w table --cacert=/etc/kubernetes/cert/ca.pem --cert=/etc/etcd/cert/etcd.pem --key=/etc/etcd/cert/etcd-key.pem --endpoints="https://172.16.60.231:2379,https://172.16.60.232:2379,https://172.16.60.233:2379" endpoint status+----------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+| ENDPOINT | ID | VERSION | DB SIZE | IS LEADER | IS LEARNER | RAFT TERM | RAFT INDEX | RAFT APPLIED INDEX | ERRORS |+----------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+| https://172.16.60.231:2379 | 79cf4f0a8c3da54b | 3.4.9 | 9.0 MB | false | false | 2 | 13 | 13 | || https://172.16.60.232:2379 | 4c0cfad24e92e45f | 3.4.9 | 9.0 MB | true | false | 2 | 13 | 13 | || https://172.16.60.233:2379 | 5f70664d346a6ebd | 3.4.9 | 9.0 MB | false | false | 2 | 13 | 13 | |+----------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+
再依次启动所有master节点的kube-apiserver服务：
# systemctl start kube-apiserver# systemctl status kube-apiserver
查看kubernetes集群状态：
[root@k8s-master01 ~]# kubectl get csNAME STATUS MESSAGE ERRORcontroller-manager Healthy okscheduler Healthy oketcd-2 Unhealthy HTTP probe failed with statuscode: 503etcd-1 Unhealthy HTTP probe failed with statuscode: 503etcd-0 Unhealthy HTTP probe failed with statuscode: 503
由于etcd服务刚重启，需要多刷几次状态就会正常：[root@k8s-master01 ~]# kubectl get csNAME STATUS MESSAGE ERRORcontroller-manager Healthy okscheduler Healthy oketcd-2 Healthy {"health":"true"}etcd- Healthy {"health":"true"}etcd-1 Healthy {"health":"true"}
查看kubernetes的资源情况：
[root@k8s-master01 ~]# kubectl get nsNAME STATUS AGEdefault Active 7d4hkevin Active 5d18hkube-node-lease Active 7d4hkube-public Active 7d4hkube-system Active 7d4h
[root@k8s-master01 ~]# kubectl get pods --all-namespacesNAMESPACE NAME READY STATUS RESTARTS AGEdefault dnsutils-ds-22q87 /1 ContainerCreating 171 7d3hdefault dnsutils-ds-bp8tm /1 ContainerCreating 138 5d18hdefault dnsutils-ds-bzzqg /1 ContainerCreating 138 5d18hdefault dnsutils-ds-jcvng 1/1 Running 171 7d3hdefault dnsutils-ds-xrl2x /1 ContainerCreating 138 5d18hdefault dnsutils-ds-zjg5l 1/1 Running 7d3hdefault kevin-t-84cdd49d65-ck47f /1 ContainerCreating 2d2hdefault nginx-ds-98rm2 1/1 Running 2 7d3hdefault nginx-ds-bbx68 1/1 Running 7d3hdefault nginx-ds-kfctv /1 ContainerCreating 1 5d18hdefault nginx-ds-mdcd9 /1 ContainerCreating 1 5d18hdefault nginx-ds-ngqcm 1/1 Running 7d3hdefault nginx-ds-tpcxs /1 ContainerCreating 1 5d18hkevin nginx-ingress-controller-797ffb479-vrq6w /1 ContainerCreating 5d18hkevin test-nginx-7d4f96b486-qd4fl /1 ContainerCreating 2d1hkevin test-nginx-7d4f96b486-qfddd /1 Running 2d1hkube-system calico-kube-controllers-578894d4cd-9rp4c 1/1 Running 1 7d3hkube-system calico-node-d7wq8 /1 PodInitializing 1 7d3h
在etcd集群数据恢复后，pod容器也会慢慢恢复到running状态。至此，kubernetes整个集群已经通过etcd备份数据恢复了。
三、后总结
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
特别注意：
备份 ETCD 集群时，只需要备份一个 ETCD 数据，然后同步到其他节点上。
恢复 ETCD 数据时，拿其中一个节点的备份数据恢复即可。
来源：https://www.cnblogs.com/kevingrace/p/14616824.html
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