kubernetes备份和恢复

备份etcd数据

首先由于ETCD有三个备份，并且会同步，所以您只需要在一台master机器上执行ETCD备份即可。

另外在运行下列命令前，确保当前机器的kube-apiserver是运行的。

ps -ef|grep kube-apiserver执行备份

export ETCD_SERVERS=$(ps -ef|grep apiserver|grep -Eo "etcd servers=.*2379"|awk -F= '{print $NF}')
mkdir -p /var/lib/etcd_backup/
export ETCDCTL_API=3 
etcdctl snapshot --endpoints=$ETCD_SERVERS --cacert=/etc/kubernetes/ssl/ca.pem --cert=/etc/kubernetes/ssl/etcd.pem --key=/etc/kubernetes/ssl/etcd-key.pem save /var/lib/etcd_backup/backup_$(date "+%Y%m%d%H%M%S").db 
Snapshot saved at /var/lib/etcd_backup/backup_20180107172459.db

执行完成后，您可以在/var/lib/etcd_backup中找到备份的snapshot

[root@iZwz95q64qi83o88y9lq4cZ etcd_backup]# cd /var/lib/etcd_backup/
[root@iZwz95q64qi83o88y9lq4cZ etcd_backup]# ls
backup_20180107172459.db
[root@iZwz95q64qi83o88y9lq4cZ etcd_backup]# du -sh backup_20180107172459.db
8.0M    backup_20180107172459.db

利用ETCD的备份恢复Kubernetes集群

首先需要分别停掉三台Master机器的kube-apiserver，确保kube-apiserver已经停止了,执行下列命令返回值为0

ps -ef|grep kube-api|grep -v grep |wc -l
0

分别在三台Master节点上，停止ETCD服务

service etcd stop

移除ETCD数据目录

mv /var/lib/etcd/data.etcd /var/lib/etcd/data.etcd_bak

分别在各个节点恢复数据,首先需要拷贝数据到每个master节点，假设备份数据存在于/var/lib/etcd_backup/backup_20180107172459.db

scp /var/lib/etcd_backup/backup_20180107172459.db root@master1:/var/lib/etcd_backup/
scp /var/lib/etcd_backup/backup_20180107172459.db root@master2:/var/lib/etcd_backup/
scp /var/lib/etcd_backup/backup_20180107172459.db root@master3:/var/lib/etcd_backup/

执行恢复命令

set -x
export ETCD_NAME=$(cat /usr/lib/systemd/system/etcd.service|grep ExecStart|grep -Eo "name.*-name-[0-9].*--client"|awk '{print $2}')
export ETCD_CLUSTER=$(cat /usr/lib/systemd/system/etcd.service|grep ExecStart|grep -Eo "initial-cluster.*--initial"|awk '{print $2}')
export ETCD_INITIAL_CLUSTER_TOKEN=$(cat /usr/lib/systemd/system/etcd.service|grep ExecStart|grep -Eo "initial-cluster-token.*"|awk '{print $2}')
export ETCD_INITIAL_ADVERTISE_PEER_URLS=$(cat /usr/lib/systemd/system/etcd.service|grep ExecStart|grep -Eo "initial-advertise-peer-urls.*--listen-peer"|awk '{print $2}')
ETCDCTL_API=3 etcdctl snapshot --cacert=/etc/kubernetes/ssl/ca.pem --cert=/etc/kubernetes/ssl/etcd.pem --key=/etc/kubernetes/ssl/etcd-client-key.pem restore /var/lib/etcd_backup/backup_20180107172459.db  --name $ETCD_NAME  --data-dir /var/lib/etcd/data.etcd  --initial-cluster $ETCD_CLUSTER  --initial-cluster-token $ETCD_INITIAL_CLUSTER_TOKEN  --initial-advertise-peer-urls $ETCD_INITIAL_ADVERTISE_PEER_URLS 
chown -R etcd:etcd /var/lib/etcd/data.etcd

分别在三个master节点启动ETCD，并且通过service命令确认启动成功

# service etcd start
# service etcd status

# export ETCD_SERVERS=$(cat /etc/kubernetes/manifests-backups/kube-apiserver.yaml |grep etcd-server|awk -F= '{print $2}')
ETCDCTL_API=3 etcdctl endpoint health --endpoints=$ETCD_SERVERS  --cacert=/etc/kubernetes/ssl/ca.pem --cert=/etc/kubernetes/ssl/etcd-client.pem --key=/etc/kubernetes/ssl/etcd-key.pem 
https://192.168.250.198:2379 is healthy: successfully committed proposal: took = 2.238886ms 
https://192.168.250.196:2379 is healthy: successfully committed proposal: took = 3.390819ms 
https://192.168.250.197:2379 is healthy: successfully committed proposal: took = 2.925103ms

检查集群是否恢复正常，可以看到集群已经正常启动了。之前部署的应用也还在。

# kubectl get cs
NAME                 STATUS    MESSAGE              ERROR
controller-manager   Healthy   ok
scheduler            Healthy   ok
etcd-0               Healthy   {"health": "true"}
etcd-2               Healthy   {"health": "true"}
etcd-1               Healthy   {"health": "true"}

Kubernetes的备份主要是通过ETCD的备份完成的。而恢复时，主要考虑的是整个顺序：停止kube-apiserver，停止ETCD，恢复数据，启动ETCD，启动kube-apiserver。