kubernetes的备份和恢复

运行生产级别的Kubernetes集群，无论您的集群运行的多稳定，定期备份是未雨绸缪，一定要做的工作。
Kubernetes集群的运行状态都保存在ETCD中，为了确保您生产环境的稳定性。建议您定期备份。下面为您介绍如何对阿里云容器服务Kubernetes进行备份和恢复。

1. 如何在备份阿里云容器服务Kubernetes的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
root      2063  2047  1 1月05 ?       00:41:01 kube-apiserver 

执行备份命令

export ETCD_SERVERS=$(ps -ef|grep apiserver|grep -Eo "etcd-servers=.*2379"|awk -F= '{print $NF}')
mkdir -p /var/lib/etcd_backup/
ETCDCTL_API=3 etcdctl snapshot --endpoints=$ETCD_SERVERS --cacert=/var/lib/etcd/cert/ca.pem --cert=/var/lib/etcd/cert/etcd-client.pem --key=/var/lib/etcd/cert/etcd-client-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

2. 利用ETCD的备份恢复Kubernetes集群

2.1 首先需要分别停掉三台Master机器的kube-apiserver，

mkdir -p /etc/kubernetes/manifests-backups
mv /etc/kubernetes/manifests/kube-apiserver.yaml /etc/kubernetes/manifests-backups/

2.2 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

2.3 分别在三台Master节点上，停止ETCD服务

service etcd stop

2.4 确保ETCD停止成功

ps -ef|grep etcd|grep -v etcd|wc -l
0

2.5 移除ETCD数据目录

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

2.6 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=/var/lib/etcd/cert/ca.pem --cert=/var/lib/etcd/cert/etcd-client.pem --key=/var/lib/etcd/cert/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

2.7 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

2.8 检查ETCD的健康

# 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=/var/lib/etcd/cert/ca.pem --cert=/var/lib/etcd/cert/etcd-client.pem --key=/var/lib/etcd/cert/etcd-client-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

2.9 如果ETCD是健康的，就到每台Master上恢复kube-apiserver

# mv /etc/kubernetes/manifests-backups/kube-apiserver.yaml /etc/kubernetes/manifests/

2.10 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"}
# kubectl get no
NAME                                 STATUS    ROLES     AGE       VERSION
cn-shenzhen.i-wz90xxpi51k2u51t5y0p   Ready     master    44d       v1.8.4
cn-shenzhen.i-wz93236e8pccdscwz3ha   Ready     master    44d       v1.8.4
cn-shenzhen.i-wz953xx6qnlzdi6vo2aa   Ready     <none>    44d       v1.8.4
cn-shenzhen.i-wz953xx6qnlzdi6vo2ab   Ready     <none>    44d       v1.8.4
kubectl get deploy
NAME      DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
nginx     1         1         1            1           23d

总结：

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。欢迎您使用阿里云容器服务Kubernetes集群。

注意：该方案仅适用于同一个集群的元数据备份和恢复，并不适用不同集群之间的迁移(migration)。

阿里云容器服务提供了托管的Kubernetes集群支持，了解更多阿里云容器服务内容， 请访问https://www.aliyun.com/product/containerservice