[TOC]

0x00 前言简述

描述:在 Kubernetes 集群中所有操作的资源数据都是存储在 etcd 数据库上, 所以防止集群节点瘫痪未正常工作或在集群迁移时,以及在出现异常的情况下能尽快的恢复集群数据,则我们需要定期针对etcd集群数据进行相应的容灾操作。

在K8S集群中或者Docker环境中,我们可以非常方便的针对 etcd 数据进行备份,通我们常在一个节点上对 etcd 做快照就能够实现etcd数据的备份,其快照文件包含所有 Kubernetes 状态和关键信息, 有了etcd集群数据备份后,例如在灾难场景(例如丢失所有控制平面节点)下也能快速恢复 Kubernetes 集群,Boss再也不同担心系统起不来呢。


0x01 环境准备

1.安装的二进制 etcdctl

描述: etcdctl 二进制文件可以在 github.com/coreos/etcd/releases 选择对应的版本下载,例如可以执行以下 install_etcdctl.sh 的脚本,修改其中的版本信息。

install_etcdctl.sh

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#!/bin/bash
# Author: WeiyiGeek
# Description: etcd 与 etcdctl 下载安装
ETCD_VER=v3.5.5
ETCD_DIR=etcd-download
DOWNLOAD_URL=https://github.com/coreos/etcd/releases/download

# Download
mkdir ${ETCD_DIR}
cd ${ETCD_DIR}
wget ${DOWNLOAD_URL}/${ETCD_VER}/etcd-${ETCD_VER}-linux-amd64.tar.gz
tar -xzvf etcd-${ETCD_VER}-linux-amd64.tar.gz

# Install
cd etcd-${ETCD_VER}-linux-amd64
cp etcdctl /usr/local/bin/

验证安装:

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$ etcdctl version
etcdctl version: 3.5.5
API version: 3.5


2.拉取带有 etcdctl 的 Docker 镜像

操作流程:

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# 镜像拉取与容器创建。
docker run --rm \
-v /data/backup:/backup \
-v /etc/kubernetes/pki/etcd:/etc/kubernetes/pki/etcd \
--env ETCDCTL_API=3 \
registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.5.1-0 \
/bin/sh -c "etcdctl version"

安装验证:

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3.5.1-0: Pulling from google_containers/etcd
e8614d09b7be: Pull complete
45b6afb4a92f: Pull complete
.......
Digest: sha256:64b9ea357325d5db9f8a723dcf503b5a449177b17ac87d69481e126bb724c263
Status: Downloaded newer image for registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.5.1-0
etcdctl version: 3.5.1
API version: 3.5


3.Kubernetes 使用 etcdctl 镜像创建Pod

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# 镜像拉取
crictl pull registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.5.5-0

# Pod 创建以及安装验证
$ kubectl run etcdctl --image=registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.5.5-0 --command -- /usr/local/bin/etcdctl version
$ kubectl logs -f etcdctl
etcdctl version: 3.5.5
API version: 3.5
$ kubectl delete pod etcdctl


0x02 备份实践

1.使用二进制安装 etcdctl 客户端工具

温馨提示: 如果是单节点 Kubernetes 我们只需要对其的 etcd 数据库进行快照备份, 如果是多主多从的集群,我们则需依次备份多个 master 节点中 etcd,防止在备份时etc数据被更改!

此处实践环境为多master高可用集群节点, 即三主节点、四从工作节点,若你对K8s集群不了解或者项搭建高可用集群的朋友,关注 WeiyiGeek 公众号回复【Kubernetes学习之路汇总】即可获得学习资料:
https://www.weiyigeek.top/wechat.html?key=Kubernetes学习之路汇总

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$ kubectl get node
NAME STATUS ROLES AGE VERSION
weiyigeek-107 Ready control-plane,master 279d v1.23.1
weiyigeek-108 Ready control-plane,master 278d v1.23.1
weiyigeek-109 Ready control-plane,master 278d v1.23.1
weiyigeek-223 Ready work 278d v1.23.1
weiyigeek-224 Ready work 278d v1.23.1
weiyigeek-225 Ready work 279d v1.23.1
weiyigeek-226 Ready work 118d v1.23.1


操作流程:

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# 1.创建etcd快照备份目录
$ mkdir -pv /backup

# 2.查看etcd证书
$ ls /etc/kubernetes/pki/etcd/
ca.crt ca.key healthcheck-client.crt healthcheck-client.key peer.crt peer.key server.crt server.key

# 3.查看 etcd 地址以及服务
$ kubectl get pod -n kube-system -o wide | grep "etcd"
etcd-weiyigeek-107 1/1 Running 1 279d 192.168.12.107 weiyigeek-107 <none><none>
etcd-weiyigeek-108 1/1 Running 0 278d 192.168.12.108 weiyigeek-108 <none><none>
etcd-weiyigeek-109 1/1 Running 0 278d 192.168.12.109 weiyigeek-109 <none><none>

# 4.此时在 107、 108 、109 主节点上查看你监听情况
$ netstat -ano | grep "107:2379"
tcp 0 0 192.168.12.107:2379 0.0.0.0:* LISTEN off (0.00/0/0)
$ netstat -ano | grep "108:2379"
tcp 0 0 192.168.12.108:2379 0.0.0.0:* LISTEN off (0.00/0/0)
$ netstat -ano | grep "109:2379"
tcp 0 0 192.168.12.109:2379 0.0.0.0:* LISTEN off (0.00/0/0)

# 5. 使用etcdctl客户端工具依次备份节点中的数据
$ etcdctl --endpoints=https://10.20.176.212:2379 \
--cacert=/etc/kubernetes/pki/etcd/ca.crt \
--cert=/etc/kubernetes/pki/etcd/healthcheck-client.crt \
--key=/etc/kubernetes/pki/etcd/healthcheck-client.key \
snapshot save /backup/etcd-snapshot.db
{"level":"info","ts":"2022-10-23T16:32:26.020+0800","caller":"snapshot/v3_snapshot.go:65","msg":"created temporary db file","path":"/backup/etcd-snapshot.db.part"}
{"level":"info","ts":"2022-10-23T16:32:26.034+0800","logger":"client","caller":"v3/maintenance.go:211","msg":"opened snapshot stream; downloading"}
{"level":"info","ts":"2022-10-23T16:32:26.034+0800","caller":"snapshot/v3_snapshot.go:73","msg":"fetching snapshot","endpoint":"https://10.20.176.212:2379"}
{"level":"info","ts":"2022-10-23T16:32:26.871+0800","logger":"client","caller":"v3/maintenance.go:219","msg":"completed snapshot read; closing"}
{"level":"info","ts":"2022-10-23T16:32:26.946+0800","caller":"snapshot/v3_snapshot.go:88","msg":"fetched snapshot","endpoint":"https://10.20.176.212:2379","size":"112 MB","took":"now"}
{"level":"info","ts":"2022-10-23T16:32:26.946+0800","caller":"snapshot/v3_snapshot.go:97","msg":"saved","path":"/backup/etcd-snapshot.db"}
Snapshot saved at /backup/etcd-snapshot.db

通过etcdctl查询Kubernetes中etcd数据,由于Kubernetes使用etcd v3版本的API,而且etcd 集群中默认使用tls认证,所以先配置几个环境变量。

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# 1.环境变量
export ETCDCTL_API=3
export ETCDCTL_CACERT=/etc/kubernetes/pki/etcd/ca.crt
export ETCDCTL_CERT=/etc/kubernetes/pki/etcd/peer.crt
export ETCDCTL_KEY=/etc/kubernetes/pki/etcd/peer.key

# 2.查询集群中所有的key列表
# –-prefix:表示查找所有以/registry为前缀的key
# --keys-only=true:表示只给出key不给出value
etcdctl --endpoints=https://10.20.176.212:2379 get /registry --prefix --keys-only=true | head -n 1
/registry/apiextensions.k8s.io/customresourcedefinitions/bgpconfigurations.crd.projectcalico.org

# 3.查询某个key的值
# -–keys-only=false : 表示要给出value,该参数默认值即为false,
# -w=json :表示输出json格式
etcdctl --endpoints=https://10.20.176.212:2379 get /registry/namespaces/default --prefix --keys-only=false -w=json | python3 -m json.tool

etcdctl --endpoints=https://10.20.176.212:2379 get /registry/namespaces/default --prefix --keys-only=false -w=json | python3 -m json.tool
{
"header": {
"cluster_id": 11404821125176160774,
"member_id": 7099450421952911102,
"revision": 30240109,
"raft_term": 3
},
"kvs": [
{
"key": "L3JlZ2lzdHJ5L25hbWVzcGFjZXMvZGVmYXVsdA==",
"create_revision": 192,
"mod_revision": 192,
"version": 1,
"value": "azhzAAoPCg.......XNwYWNlEGgAiAA=="
}
],
"count": 1
}

# 4.其 Key / Value 都是采用 base64 编码
echo -e "L3JlZ2lzdHJ5L25hbWVzcGFjZXMvZGVmYXVsdA==" | base64 -d
echo -e "azhzAAoPCgJ2MRIJTmFtZXNwYWNlEogCCu0BCgdkZWZhdWx0EgAaACIAKiQ5ZDQyYmYxMy03OGM0LTQ4NzQtOThiYy05NjNlMDg1MDYyZjYyADgAQggIo8yllQYQAFomChtrdWJlcm5ldGVzLmlvL21ldGFkYXRhLm5hbWUSB2RlZmF1bHR6AIoBfQoOa3ViZS1hcGlzZXJ2ZXISBlVwZGF0ZRoCdjEiCAijzKWVBhAAMghGaWVsZHNWMTpJCkd7ImY6bWV0YWRhdGEiOnsiZjpsYWJlbHMiOnsiLiI6e30sImY6a3ViZXJuZXRlcy5pby9tZXRhZGF0YS5uYW1lIjp7fX19fUIAEgwKCmt1YmVybmV0ZXMaCAoGQWN0aXZlGgAiAA==" | base64 -d

# 5.实际上述value编码解码后的的内容如下:
$ kubectl get ns default -o yaml
apiVersion: v1
kind: Namespace
metadata:
creationTimestamp: "2022-06-15T04:54:59Z"
labels:
kubernetes.io/metadata.name: default
name: default
resourceVersion: "192"
uid: 9d42bf13-78c4-4874-98bc-963e085062f6
spec:
finalizers:
- kubernetes
status:
phase: Active

# 5.Pod 资源信息查看
etcdctl --endpoints=https://10.20.176.212:2379 get /registry/pods/default --prefix --keys-only=true
# /registry/pods/default/nfs-dev-nfs-subdir-external-provisioner-cf7684f8b-fzl9h
# /registry/pods/default/nfs-local-nfs-subdir-external-provisioner-6f97d44bb8-424tk

etcdctl --endpoints=https://10.20.176.212:2379 get /registry/pods/default --prefix --keys-only=true -w=json | python3 -m json.tool
{
"header": {
"cluster_id": 11404821125176160774,
"member_id": 7099450421952911102,
"revision": 30442415,
"raft_term": 3
},
"kvs": [
{ # 实际上该编码是 /registry/pods/default/nfs-dev-nfs-subdir-external-provisioner-cf7684f8b-fzl9h
"key": "L3JlZ2lzdHJ5L3BvZHMvZGVmYXVsdC9uZnMtZGV2LW5mcy1zdWJkaXItZXh0ZXJuYWwtcHJvdmlzaW9uZXItY2Y3Njg0ZjhiLWZ6bDlo",
"create_revision": 5510865,
"mod_revision": 5510883,
"version": 5
},
{
"key": "L3JlZ2lzdHJ5L3BvZHMvZGVmYXVsdC9uZnMtbG9jYWwtbmZzLXN1YmRpci1leHRlcm5hbC1wcm92aXNpb25lci02Zjk3ZDQ0YmI4LTQyNHRr",
"create_revision": 5510967,
"mod_revision": 5510987,
"version": 5
}
],
"count": 2
}


2.使用Docker镜像安装 etcdctl 客户端工具

描述: 在装有Docker环境的机器,我们可以非常方便的备份K8s集群中的etcd数据库,此处我已经安装好了Docker,若有不了解Docker或者需要搭建Docker环境中童鞋。

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# 1.Docker 实践环境
$ docker version
Client: Docker Engine - Community
Version 20.10.3
.......
Server: Docker Engine - Community
Engine:
Version: 20.10.3

# 2.etcd 备份文件存储的目录
$ mkdir -vp /backup

# 3.执行docker创建容器,在备份数据库后便删除该容器。
$ docker run --rm \
-v /backup:/backup \
-v /etc/kubernetes/pki/etcd:/etc/kubernetes/pki/etcd \
--env ETCDCTL_API=3 \
registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.5.1-0 \
/bin/sh -c "etcdctl --endpoints=https://192.168.12.107:2379 \
--cacert=/etc/kubernetes/pki/etcd/ca.crt \
--key=/etc/kubernetes/pki/etcd/healthcheck-client.key \
--cert=/etc/kubernetes/pki/etcd/healthcheck-client.crt \
snapshot save /backup/etcd-snapshot.db"
# {"level":"info","ts":1666515535.63076,"caller":"snapshot/v3_snapshot.go:68","msg":"created temporary db file","path":"/backup/etcd-snapshot.db.part"}
# {"level":"info","ts":1666515535.6411893,"logger":"client","caller":"v3/maintenance.go:211","msg":"opened snapshot stream; downloading"}
# {"level":"info","ts":1666515535.6419039,"caller":"snapshot/v3_snapshot.go:76","msg":"fetching snapshot","endpoint":"https://192.168.12.107:2379"}
# {"level":"info","ts":1666515535.9170482,"logger":"client","caller":"v3/maintenance.go:219","msg":"completed snapshot read; closing"}
# {"level":"info","ts":1666515535.931862,"caller":"snapshot/v3_snapshot.go:91","msg":"fetched snapshot","endpoint":"https://192.168.12.107:2379","size":"9.0 MB","took":"now"}
# {"level":"info","ts":1666515535.9322069,"caller":"snapshot/v3_snapshot.go:100","msg":"saved","path":"/backup/etcd-snapshot.db"}
Snapshot saved at /backup/etcd-snapshot.db

# 4.查看备份的etcd快照文件
ls -alh /backup/etcd-snapshot.db
-rw------- 1 root root 8.6M Oct 23 16:58 /backup/etcd-snapshot.db

使用 Docker 容器查看 k8s 集群中的etcd数据库中的数据。

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$ docker run --rm \
-v /backup:/backup \
-v /etc/kubernetes/pki/etcd:/etc/kubernetes/pki/etcd \
--env ETCDCTL_API=3 \
--env ETCDCTL_CACERT=/etc/kubernetes/pki/etcd/ca.crt \
--env ETCDCTL_CERT=/etc/kubernetes/pki/etcd/peer.crt \
--env ETCDCTL_KEY=/etc/kubernetes/pki/etcd/peer.key \
registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.5.1-0 \
/bin/sh -c "etcdctl --endpoints=https://192.168.12.107:2379 get /registry/namespaces/default -w=json"

执行结果:

WeiyiGeek.Docker容器查询Kubernetes集群中etcd数据库中k/v示例图


3.在kubernetes集群中快速创建pod进行手动备份

准备一个Pod资源清单并部署

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cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
name: etcd-backup
labels:
tool: backup
spec:
containers:
- name: redis
image: registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.5.5-0
imagePullPolicy: IfNotPresent
command:
- sh
- -c
- "etcd"
env:
- name: ETCDCTL_API
value: "3"
- name: ETCDCTL_CACERT
value: "/etc/kubernetes/pki/etcd/ca.crt"
- name: ETCDCTL_CERT
value: "/etc/kubernetes/pki/etcd/healthcheck-client.crt"
- name: ETCDCTL_KEY
value: "/etc/kubernetes/pki/etcd/healthcheck-client.key"
volumeMounts:
- name: "pki"
mountPath: "/etc/kubernetes"
- name: "backup"
mountPath: "/backup"
volumes:
- name: pki
hostPath:
path: "/etc/kubernetes" # 证书目录
type: "DirectoryOrCreate"
- name: "backup"
hostPath:
path: "/storage/dev/backup" # 数据备份目录
type: "DirectoryOrCreate"
restartPolicy: Never
nodeSelector:
node-role.kubernetes.io/master: "" # 绑定在主节点中
EOF
pod/etcd-backup created


进入到该Pod终端之中执行相应的备份命令

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~$ kubectl exec -it etcd-backup sh
# 快照备份
sh-5.1# export RAND=$RANDOM
sh-5.1# etcdctl --endpoints=https://192.168.12.107:2379 snapshot save /backup/etcd-107-${RAND}-snapshot.db
sh-5.1# etcdctl --endpoints=https://192.168.12.108:2379 snapshot save /backup/etcd-108-${RAND}-snapshot.db
Snapshot saved at /backup/etcd-108-32616-snapshot.db
sh-5.1# etcdctl --endpoints=https://192.168.12.109:2379 snapshot save /backup/etcd-109-${RAND}-snapshot.db

# etcd 节点成员
sh-5.1# etcdctl member list --endpoints=https://192.168.12.107:2379 --endpoints=https://192.168.12.108:2379 --endpoints=https://192.168.12.109:2379

2db31a5d67ec1034, started, weiyigeek-108, https://192.168.12.108:2380, https://192.168.12.108:2379, false
42efe7cca897d765, started, weiyigeek-109, https://192.168.12.109:2380, https://192.168.12.109:2379, false
471323846709334f, started, weiyigeek-107, https://192.168.12.107:2380, https://192.168.12.107:2379, false


# etcd 节点健康信息
sh-5.1# etcdctl endpoint health --endpoints=https://192.168.12.107:2379 --endpoints=https://192.168.12.108:2379 --endpoints=https://192.168.12.109:2379

https://192.168.12.107:2379 is healthy: successfully committed proposal: took = 11.930331ms
https://192.168.12.109:2379 is healthy: successfully committed proposal: took = 11.930993ms
https://192.168.12.108:2379 is healthy: successfully committed proposal: took = 109.515933ms


# etcd 节点状态及空间占用信息
sh-5.1# etcdctl endpoint status --endpoints=https://192.168.12.107:2379 --endpoints=https://192.168.12.108:2379 --endpoints=https://192.168.12.109:2379

https://192.168.12.107:2379, 471323846709334f, 3.5.1, 9.2 MB, false, false, 4, 71464830, 71464830,
https://192.168.12.108:2379, 2db31a5d67ec1034, 3.5.1, 9.2 MB, false, false, 4, 71464830, 71464830,
https://192.168.12.109:2379, 42efe7cca897d765, 3.5.1, 9.2 MB, true, false, 4, 71464830, 71464830, # 此处为主

至此,手动备份etcd集群数据快照完毕!


4.在kubernetes集群中使用CronJob资源控制器进行定时备份

首先准备一个cronJob资源清单:

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cat > etcd-database-backup.yaml <<'EOF'
apiVersion: batch/v1
kind: CronJob
metadata:
name: etcd-database-backup
annotations:
descript: "etcd数据库定时备份"
spec:
schedule: "*/5 * * * *" # 表示每5分钟运行一次
jobTemplate:
spec:
template:
spec:
containers:
- name: etcdctl
image: registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.5.5-0
env:
- name: ETCDCTL_API
value: "3"
- name: ETCDCTL_CACERT
value: "/etc/kubernetes/pki/etcd/ca.crt"
- name: ETCDCTL_CERT
value: "/etc/kubernetes/pki/etcd/healthcheck-client.crt"
- name: ETCDCTL_KEY
value: "/etc/kubernetes/pki/etcd/healthcheck-client.key"
command:
- /bin/sh
- -c
- |
export RAND=$RANDOM
etcdctl --endpoints=https://192.168.12.107:2379 snapshot save /backup/etcd-107-${RAND}-snapshot.db
etcdctl --endpoints=https://192.168.12.108:2379 snapshot save /backup/etcd-108-${RAND}-snapshot.db
etcdctl --endpoints=https://192.168.12.109:2379 snapshot save /backup/etcd-109-${RAND}-snapshot.db
volumeMounts:
- name: "pki"
mountPath: "/etc/kubernetes"
- name: "backup"
mountPath: "/backup"
imagePullPolicy: IfNotPresent
volumes:
- name: "pki"
hostPath:
path: "/etc/kubernetes"
type: "DirectoryOrCreate"
- name: "backup"
hostPath:
path: "/storage/dev/backup" # 数据备份目录
type: "DirectoryOrCreate"
nodeSelector: # 将Pod绑定在主节点之中,否则只能将相关证书放在各个节点能访问的nfs共享存储中
node-role.kubernetes.io/master: ""
restartPolicy: Never
EOF

创建cronjob资源清单:

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kubectl apply -f etcd-database-backup.yaml
# cronjob.batch/etcd-database-backup created

查看创建的cronjob资源及其集群etcd备份:

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NAME                                 SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE
cronjob.batch/etcd-database-backup */5 * * * * False 0 21s 14m

NAME READY STATUS RESTARTS AGE
pod/etcd-database-backup-27776740-rhzkk 0/1 Completed 0 21s

查看定时Pod日志以及备份文件:

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kubectl logs -f pod/etcd-database-backup-27776740-rhzkk
Snapshot saved at /backup/etcd-107-25615-snapshot.db
Snapshot saved at /backup/etcd-108-25615-snapshot.db
Snapshot saved at /backup/etcd-109-25615-snapshot.db


$ ls -lt # 显示最新备份的文件按照时间排序
total 25M
-rw------- 1 root root 8.6M Oct 24 21:12 etcd-107-25615-snapshot.db
-rw------- 1 root root 7.1M Oct 24 21:12 etcd-108-25615-snapshot.db
-rw------- 1 root root 8.8M Oct 24 21:12 etcd-109-25615-snapshot.db

至此集群中的etcd快照数据备份完毕!


0x02 恢复实践

1.单master节点恢复

描述: 当单master集群节点资源清单数据丢失时,我们可采用如下方式进行快速恢复数据。

操作流程:

温馨提示: 如果是单节点的k8S集群则使用如下命令恢复

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 mv /etc/kubernetes/manifests/ /etc/kubernetes/manifests-backup/
mv /var/lib/etcd /var/lib/etcd.bak

ETCDCTL_API=3 etcdctl snapshot restore /backup/etcd-212-32616-snapshot.db --data-dir=/var/lib/etcd/ --endpoints=https://10.20.176.212:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt --cert=/etc/kubernetes/pki/etcd/peer.crt --key=/etc/kubernetes/pki/etcd/peer.key

2.多master节点恢复

1.温馨提示,此处的集群etcd数据库是安装在Kubernetes集群之中的,并非外部独立安装部署的。

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$ kubectl get pod -n kube-system  etcd-devtest-master-212 etcd-devtest-master-213 etcd-devtest-master-214
NAME READY STATUS RESTARTS AGE
etcd-devtest-master-212 1/1 Running 3 134d
etcd-devtest-master-213 1/1 Running 0 134d
etcd-devtest-master-214 1/1 Running 0 134d

2.前面我们提到过,在进行恢复前需要查看 etcd 集群当前成员以及监控状态。

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# etcd 集群成员列表
ETCDCTL_API=3 etcdctl member list --endpoints=https://10.20.176.212:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt --cert=/etc/kubernetes/pki/etcd/peer.crt --key=/etc/kubernetes/pki/etcd/peer.key
6286508b550016fe, started, devtest-master-212, https://10.20.176.212:2380, https://10.20.176.212:2379, false
9dd15f852caf8e05, started, devtest-master-214, https://10.20.176.214:2380, https://10.20.176.214:2379, false
e0f23bd90b7c7c0d, started, devtest-master-213, https://10.20.176.213:2380, https://10.20.176.213:2379, false

# etcd 集群节点状态查看主从节点
ETCDCTL_API=3 etcdctl endpoint status --endpoints=https://10.20.176.212:2379 --endpoints=https://10.20.176.213:2379 --endpoints=https://10.20.176.214:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt --cert=/etc/kubernetes/pki/etcd/peer.crt --key=/etc/kubernetes/pki/etcd/peer.key --write-out table

# etcd 集群节点健康信息筛选出不健康的节点
ETCDCTL_API=3 etcdctl endpoint health --endpoints=https://10.20.176.212:2379 --endpoints=https://10.20.176.213:2379 --endpoints=https://10.20.176.214:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt --cert=/etc/kubernetes/pki/etcd/peer.crt --key=/etc/kubernetes/pki/etcd/peer.key
https://10.20.176.212:2379 is healthy: successfully committed proposal: took = 14.686875ms
https://10.20.176.214:2379 is healthy: successfully committed proposal: took = 16.201187ms
https://10.20.176.213:2379 is healthy: successfully committed proposal: took = 18.962462ms

3.停掉所有Master机器的kube-apiserver和etcd ,然后在利用备份进行恢复该节点的etcd数据。

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mv /etc/kubernetes/manifests/ /etc/kubernetes/manifests-backup/

# 在该节点上删除 /var/lib/etcd
mv /var/lib/etcd /var/lib/etcd.bak

# 利用快照进行恢复,注意etcd集群中可以用同一份snapshot恢复。
ETCDCTL_API=3 etcdctl snapshot restore /backup/etcd-212-32616-snapshot.db --data-dir=/var/lib/etcd --name=devtest-master-212 --cacert=/etc/kubernetes/pki/etcd/ca.crt --cert=/etc/kubernetes/pki/etcd/peer.crt --key=/etc/kubernetes/pki/etcd/peer.key --initial-cluster-token=etcd-cluster-0 --initial-cluster=devtest-master-212=https://10.20.176.212:2380,devtest-master-213=https://10.20.176.213:2380,devtest-master-214=https://10.20.176.214:2380 --initial-advertise-peer-urls=https://10.20.176.212:2380

温馨提示: 当节点加入控制平面 control-plane 后为 API Server、Controller Manager 和 Scheduler 生成静态Pod配置清单,主机上的kubelet服务会监视 /etc/kubernetes/manifests目录中的配置清单的创建、变动和删除等状态变动,并根据变动完成Pod创建、更新或删除操作。因此,这两个阶段创建生成的各配置清单将会启动Master组件的相关Pod

4.然后启动 etcd 和 apiserver 并查看 pods是否恢复正常。

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# 查看 etcd pod
$ kubectl get pod -n kube-system -l component=etcd

# 查看组件健康状态
$ kubectl get componentstatuses
Warning: v1 ComponentStatus is deprecated in v1.19+
NAME STATUS MESSAGE ERROR
scheduler Healthy ok
controller-manager Healthy ok
etcd-0 Healthy {"health":"true","reason":""}

3.K8S集群中etcd数据库节点数据不一致问题解决实践

发现etcd数据不一致,执行kubectl get pod -n xxx获取的信息资源不一样, etcdctl 直接查询了 etcd 集群状态和集群数据,返回结果显示 3 个节点状态都正常,且 RaftIndex 一致,观察 etcd 的日志也并未发现报错信息,唯一可疑的地方是 3 个节点的 dbsize 差别较大

etcd 数据不一致 ?

由于从 kube-apiserver 的日志中同样无法提取出能够帮助解决问题的有用信息,起初我们只能猜测可能是 kube-apiserver 的缓存更新异常导致的。正当我们要从这个切入点去解决问题时,该同事反馈了一个更诡异的问题——自己新创建的 Pod,通过 kubectl查询 Pod 列表,突然消失了!纳尼?这是什么骚操作?经过我们多次测试查询发现,通过 kubectl 来 list pod 列表,该 pod 有时候能查到,有时候查不到。那么问题来了,K8s api 的 list 操作是没有缓存的,数据是 kube-apiserver 直接从 etcd 拉取返回给客户端的,难道是 etcd 本身出了问题?

众所周知,etcd 本身是一个强一致性的 KV 存储,在写操作成功的情况下,两次读请求不应该读取到不一样的数据。怀着不信邪的态度,我们通过 etcdctl 直接查询了 etcd 集群状态和集群数据,返回结果显示 3 个节点状态都正常,且 RaftIndex 一致,观察 etcd 的日志也并未发现报错信息,唯一可疑的地方是 3 个节点的 dbsize 差别较大。接着,我们又将 client 访问的 endpoint 指定为不同节点地址来查询每个节点的 key 的数量,结果发现 3 个节点返回的 key 的数量不一致,甚至两个不同节点上 Key 的数量差最大可达到几千!而直接通过 etcdctl 查询刚才创建的 Pod,发现访问某些 endpoint 能够查询到该 pod,而访问其他 endpoint 则查不到。至此,基本可以确定 etcd 集群的节点之间确实存在数据不一致现象。

ETCDCTL_API=3 etcdctl endpoint status –endpoints=https://192.168.12.108:2379 –endpoints=https://192.168.12.107:2379 –endpoints=https://192.168.12.109:2379 –cacert=/etc/kubernetes/pki/etcd/ca.crt –cert=/etc/kubernetes/pki/etcd/peer.crt –key=/etc/kubernetes/pki/etcd/peer.key

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https://192.168.12.108:2379, 2db31a5d67ec1034, 3.5.1, 7.4 MB, false, false, 4, 72288139, 72288139,
https://192.168.12.107:2379, 471323846709334f, 3.5.1, 9.0 MB, false, false, 4, 72288139, 72288139,
https://192.168.12.109:2379, 42efe7cca897d765, 3.5.1, 9.2 MB, true, false, 4, 72288139, 72288139,

root@weiyigeek-107:~# ETCDCTL_API=3 etcdctl get / –prefix –keys-only –endpoints=https://192.168.12.107:2379 –cacert=/etc/kubernetes/pki/etcd/ca.crt –cert=/etc/kubernetes/pki/etcd/peer.crt –key=/etc/kubernetes/pki/etcd/peer.key | wc -l
1620

root@weiyigeek-107:~# ETCDCTL_API=3 etcdctl get / –prefix –keys-only –endpoints=https://192.168.12.108:2379 –cacert=/etc/kubernetes/pki/etcd/ca.crt –cert=/etc/kubernetes/pki/etcd/peer.crt –key=/etc/kubernetes/pki/etcd/peer.key | wc -l
1620

root@weiyigeek-107:~# ETCDCTL_API=3 etcdctl get / –prefix –keys-only –endpoints=https://192.168.12.109:2379 –cacert=/etc/kubernetes/pki/etcd/ca.crt –cert=/etc/kubernetes/pki/etcd/peer.crt –key=/etc/kubernetes/pki/etcd/peer.key | wc -l
1620

l
+—————————–+——————+———+———+———–+———–+————+
| ENDPOINT | ID | VERSION | DB SIZE | IS LEADER | RAFT TERM | RAFT INDEX |
+—————————–+——————+———+———+———–+———–+————+
| https://192.168.12.108:2379 | 2db31a5d67ec1034 | 3.5.1 | 7.4 MB | false | 4 | 72291872 |
| https://192.168.12.107:2379 | 471323846709334f | 3.5.1 | 9.0 MB | false | 4 | 72291872 |
| https://192.168.12.109:2379 | 42efe7cca897d765 | 3.5.1 | 9.2 MB | true | 4 | 72291872 |
+—————————–+——————+———+———+———–+———–+————+

ETCDCTL_API=3 etcdctl endpoint status –endpoints=https://192.168.12.107:2379 –endpoints=https://192.168.12.108:2379 –endpoints=https://192.168.12.109:2379 –write-out table
+—————————–+——————+———+———+———–+————+———–+————+——————–+——–+
| ENDPOINT | ID | VERSION | DB SIZE | IS LEADER | IS LEARNER | RAFT TERM | RAFT INDEX | RAFT APPLIED INDEX | ERRORS |
+—————————–+——————+———+———+———–+————+———–+————+——————–+——–+
| https://192.168.12.107:2379 | 471323846709334f | 3.5.1 | 9.0 MB | false | false | 4 | 72292452 | 72292452 | |
| https://192.168.12.108:2379 | 2db31a5d67ec1034 | 3.5.1 | 7.4 MB | false | false | 4 | 72292452 | 72292452 | |
| https://192.168.12.109:2379 | 42efe7cca897d765 | 3.5.1 | 9.2 MB | true | false | 4 | 72292452 | 72292452 | |
+—————————–+——————+———+———+———–+————+———–+————+——————–+——–+