此版本的NFS为单点,仅为练习使用,生产环境建议使用cephfs的卷类型,避免单点。或者通过keepalived加Sersync的方案对NFS作容灾处理即可用于生产环境。当然,对于开发或测试环境,方便起见,直接使用单点的NFS加mongodb statefulSet方案是最为清晰简便的。
mongodb集群部署分两种情况,一是只部署副本机制,不使用分片,另一种情况是使用分片集群。使用分片的情况下会略复杂,但基本部署方法和只部署副本的方法是差不多的,只不过是多了一些角色。这里只介绍部署副本集群到k8s集群。
部署前提:一个高可用k8s集群和NFS storage class。
主机名 | 业务概述 |
---|---|
k8s-register-node | harbor私服 |
lb-node-1 | nginx负载、helm |
lb-node-2 | nginx负载 |
k8s-master-1 | k8s master(controlplane,worker,etcd) |
k8s-master-2 | k8s master(controlplane,worker,etcd) |
k8s-master-3 | k8s master(controlplane,worker,etcd) |
k8s-storage-3 | NFS-Server |
部署一主一从一仲裁的集群,可以看出,因为NFS服务只有一个,因此这里是存在单点故障的,除此单点外,mongodb本身的服务具有高可用,副本机制如下图:
如上图,共部署三个副本,其中有一个仲裁节点,此节点并不保存数据。主节点负责读写,从节点通过Raft协议同步数据, 可作读节点。
mongodb副本集必须有3个以上成员,且成员个数必须为奇数。主备节点存储数据,仲裁节点不存储数据。客户端同时连接主节点与备节点,不连接仲裁节点。 仲裁节点是一种特殊的节点,它本身并不存储数据,主要的作用是决定哪一个备节点在主节点挂掉之后提升为主节点,所以客户端不需要连接此节点。
每个服务器都必须有keyFile文件,且该keyFile文件必须相同,各服务器才能正常交互。
openssl rand -base64 756 > /home/kmning/mongodb/mongodb.key
PV我们直接使用NFS storage class的动态制备,因此我们定义好statefulset和Service就可以把mongodb集群安装好,最后手动初始化集群即可。
下面的kefile内容即是上面生成的mongodb.key对应的内容。
mongodb-statefulset.yaml
---
apiVersion: v1
kind: ConfigMap
metadata:
name: mongodb-rs-cm
data:
keyfile: |
上面生成的keyfile内容
mongod_rs.conf: |+
systemLog:
destination: file
logAppend: true
path: /data/mongod.log
storage:
dbPath: /data
journal:
enabled: true
directoryPerDB: true
wiredTiger:
engineConfig:
cacheSizeGB: 4
directoryForIndexes: true
processManagement:
fork: true
timeZoneInfo: /usr/share/zoneinfo
pidFilePath: /data/mongod.pid
net:
port: 27017
bindIp: 0.0.0.0
maxIncomingConnections: 5000
security:
keyFile: /data/configdb/keyfile
authorization: enabled
replication:
oplogSizeMB: 5120
replSetName: trunkingReplSet
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: mongodb-rs
spec:
serviceName: mongodb-rs
replicas: 3
selector:
matchLabels:
app: mongodb-rs
template:
metadata:
labels:
app: mongodb-rs
spec:
containers:
- name: mongo
image: k8s-register-node.com:443/mongo:4.4.10
ports:
- containerPort: 27017
name: mongo-pod-port
command: ["sh"]
args:
- "-c"
- |
set -ex
mongod --config /data/configdb/mongod_rs.conf
sleep infinity
env:
- name: POD_IP
valueFrom:
fieldRef:
fieldPath: status.podIP
volumeMounts:
- name: conf
mountPath: /data/configdb
readOnly: false
- name: data
mountPath: /data
readOnly: false
volumes:
- name: conf
configMap:
name: mongodb-rs-cm
defaultMode: 0600
volumeClaimTemplates:
- metadata:
name: data
spec:
accessModes: ["ReadWriteOnce"]
resources:
requests:
storage: 300Gi
storageClassName: managed-nfs-storage
configmap也一同建立,这里以默认的namespace进行的部署,实际情况因选择自己的namespace。 这里要注意,keyfile权限设置600否则无法启动mongod。 fork如果配置true的话,在启动命令后我写了sleep infinity,否则容器立马会退出。
注意上面,configmap相当于定义了一个keyfile文件和一个mongod_rs.conf配置文件,在mongod_rs.conf配置文件中直接使用keyfile,然后在StatefulSet中对副本模板定义时直接挂载了mongod_rs.conf中定义的数据目录和配置文件目录,这样一来k8s就可以利用这些配置文件和副本状态集模板定义构建StatefulSet,而存储的PV则交给了NFS的storage Class。
注意上面的keyfile内容定义,以一行的形式保存,不能有tab。
安装上面的statefuleSet
kmning@k8s-master-1:~/mongodb$ kubectl create -f mongodb-statefulset.yaml
configmap/mongodb-rs-cm created
statefulset.apps/mongodb-rs created
查看状态
kmning@k8s-master-1:~/mongodb$ kubectl get pods
NAME READY STATUS RESTARTS AGE
mongodb-rs-0 1/1 Running 0 4m26s
mongodb-rs-1 1/1 Running 0 4m1s
mongodb-rs-2 1/1 Running 0 3m35s
可见,三个pod正在有序创建完成,再查看一下PV即可发现,三块PV和PVC由NFS的storage class给我们动态制备了。
kmning@k8s-master-1:~/mongodb$ kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-14d12757-c32e-4e26-857e-7e6fb22c637f 10Gi RWX Delete Bound default/data-nacos-0 managed-nfs-storage 6d6h
pvc-50a5d0e7-0ae1-41a3-ae43-29c8279da460 300Gi RWO Delete Bound default/data-mongodb-rs-2 managed-nfs-storage 3m6s
pvc-a213fa79-bf84-465d-b7ee-fe9a2713d329 300Gi RWO Delete Bound default/data-mongodb-rs-0 managed-nfs-storage 3m57s
pvc-b9629010-ce4b-4c04-83fb-ee2feae32040 300Gi RWO Delete Bound default/data-mongodb-rs-1 managed-nfs-storage 3m31s
pvc-bb1beed7-5303-4fea-9bc1-4b1c3f762b18 10Gi RWX Delete Bound default/data-nacos-2 managed-nfs-storage 6d6h
pvc-cb9de849-bfaa-4c42-9328-c90831336c68 10Gi RWX Delete Bound default/data-nacos-1 managed-nfs-storage 6d6h
kmning@k8s-master-1:~/mongodb$ kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
data-mongodb-rs-0 Bound pvc-a213fa79-bf84-465d-b7ee-fe9a2713d329 300Gi RWO managed-nfs-storage 3m54s
data-mongodb-rs-1 Bound pvc-b9629010-ce4b-4c04-83fb-ee2feae32040 300Gi RWO managed-nfs-storage 3m28s
data-mongodb-rs-2 Bound pvc-50a5d0e7-0ae1-41a3-ae43-29c8279da460 300Gi RWO managed-nfs-storage 3m2s
data-nacos-0 Bound pvc-14d12757-c32e-4e26-857e-7e6fb22c637f 10Gi RWX managed-nfs-storage 6d6h
data-nacos-1 Bound pvc-cb9de849-bfaa-4c42-9328-c90831336c68 10Gi RWX managed-nfs-storage 6d6h
data-nacos-2 Bound pvc-bb1beed7-5303-4fea-9bc1-4b1c3f762b18 10Gi RWX managed-nfs-storage 6d6h
上面已经成功创建了mongodb的statefulset对应的三个Pod,但目前外部尚不可访问,先创建一个ClusterIP类型的Service,用以达到被其他pod访问的目的。
mongod-svc.yml
apiVersion: v1
kind: Service
metadata:
name: mongodb-rs
namespace: default
spec:
ports:
- port: 27017
protocol: TCP
targetPort: mongo-pod-port
selector:
app: mongodb-rs
type: ClusterIP
注意上面的service name要和StatefulSet中定义的serviceName对应起来。另外 ,targetPort我使用了mongodb定义的port的名称,这样一来,即使后端的mongodb端口更换了,Service也不用修改。
创建
euht@k8s-master-1:~/mongodb$ kubectl create -f mongod-svc.yml
service/mongodb-rs created
创建后k8s就给这个Service分配了集群IP,查看如
kmning@k8s-master-1:~/mongodb$ kubectl get svc mongodb-rs -o yaml
apiVersion: v1
kind: Service
metadata:
creationTimestamp: "2023-04-27T02:20:58Z"
name: mongodb-rs
namespace: default
resourceVersion: "3746349"
uid: 758812a2-9d5c-457f-ab91-264fafbf9998
spec:
clusterIP: 10.43.149.68
clusterIPs:
- 10.43.149.68
internalTrafficPolicy: Cluster
ipFamilies:
- IPv4
ipFamilyPolicy: SingleStack
ports:
- port: 27017
protocol: TCP
targetPort: mongo-pod-port
selector:
app: mongodb-rs
sessionAffinity: None
type: ClusterIP
status:
loadBalancer: {}
然后,在k8s集群内,我们都可以利用集群IP 10.43.232.149去访问到后端mongodb的pod。
kmning@k8s-master-1:~/mongodb$ kubectl describe svc mongodb-rs
Name: mongodb-rs
Namespace: default
Labels:
Annotations:
Selector: app=mongodb-rs
Type: ClusterIP
IP Family Policy: SingleStack
IP Families: IPv4
IP: 10.43.149.68
IPs: 10.43.149.68
Port: 27017/TCP
TargetPort: mongo-pod-port/TCP
Endpoints: 10.42.0.33:27017,10.42.2.36:27017,10.42.4.13:27017
Session Affinity: None
Events:
可以看到,这个集群IP后面拥有三个Endpoints,对应三个mongodb pod。
现在我们可以通过域名的方式来设置replica set,也不用关心pod会变化的ip地址了。 域名为:$(podname).$(service name).$(namespace).svc.cluster.local
可以进行一次验证,mongodb-rs-0通过域名连接mongodb-rs-2
kmning@k8s-master-1:~/mongodb$ kubectl exec -it mongodb-rs-0 -- mongo mongodb-rs-2.mongodb-rs.default.svc.cluster.local
MongoDB shell version v4.4.10
connecting to: mongodb://mongodb-rs-2.mongodb-rs.default.svc.cluster.local:27017/test?compressors=disabled&gssapiServiceName=mongodb
Implicit session: session { "id" : UUID("64c8e67e-50ca-480a-ab5d-473b291239b2") }
MongoDB server version: 4.4.10
Welcome to the MongoDB shell.
For interactive help, type "help".
For more comprehensive documentation, see
https://docs.mongodb.com/
Questions? Try the MongoDB Developer Community Forums
https://community.mongodb.com
>
可以看出,正常连接。事实上通过域名连接,k8s会先通过dns服务查找到集群IP,然后通过Service找到Pod对应的IP,然后再进行连接。后续mongodb的pod实例怎么变,此域名都不会变,这样一来用域名设置的有状态配置就不会因为pod的IP改变而变得不可用。
上面已经搭建好mongodb的各个副本,但它们之间尚未有联系,随便登录一个副本进行初始化以建立副本集。
可以登录任何的一个副本进行设置,注意host字段要使用服务域名,因为statefulset的pod的域名是稳定不会变的。
kubectl exec -it mongodb-rs-0 -- mongo
初始化
use admin;
rs.initiate(
{
_id: "yourReplSet",
members: [
{ _id : 0, host : "mongodb-rs-0.mongodb-rs.default.svc.cluster.local:27017",priority: 50 },
{ _id : 1, host : "mongodb-rs-1.mongodb-rs.default.svc.cluster.local:27017" ,priority: 60},
{ _id : 2, host : "mongodb-rs-2.mongodb-rs.default.svc.cluster.local:27017",arbiterOnly: true }
]
}
)
查看状态
rs.status();
yourReplSet:SECONDARY> rs.status();
{
"set" : "yourReplSet",
"date" : ISODate("2023-04-26T10:13:56.173Z"),
"myState" : 2,
"term" : NumberLong(2),
"syncSourceHost" : "mongodb-rs-1.mongodb-rs.default.svc.cluster.local:27017",
"syncSourceId" : 1,
"heartbeatIntervalMillis" : NumberLong(2000),
"majorityVoteCount" : 2,
"writeMajorityCount" : 2,
"votingMembersCount" : 3,
"writableVotingMembersCount" : 2,
"optimes" : {
"lastCommittedOpTime" : {
"ts" : Timestamp(1682504019, 1),
"t" : NumberLong(2)
},
"lastCommittedWallTime" : ISODate("2023-04-26T10:13:39.160Z"),
"readConcernMajorityOpTime" : {
"ts" : Timestamp(1682504019, 1),
"t" : NumberLong(2)
},
"readConcernMajorityWallTime" : ISODate("2023-04-26T10:13:39.160Z"),
"appliedOpTime" : {
"ts" : Timestamp(1682504019, 1),
"t" : NumberLong(2)
},
"durableOpTime" : {
"ts" : Timestamp(1682504019, 1),
"t" : NumberLong(2)
},
"lastAppliedWallTime" : ISODate("2023-04-26T10:13:39.160Z"),
"lastDurableWallTime" : ISODate("2023-04-26T10:13:39.160Z")
},
"lastStableRecoveryTimestamp" : Timestamp(1682503991, 4),
"electionParticipantMetrics" : {
"votedForCandidate" : true,
"electionTerm" : NumberLong(2),
"lastVoteDate" : ISODate("2023-04-26T10:13:22.875Z"),
"electionCandidateMemberId" : 1,
"voteReason" : "",
"lastAppliedOpTimeAtElection" : {
"ts" : Timestamp(1682503992, 1),
"t" : NumberLong(1)
},
"maxAppliedOpTimeInSet" : {
"ts" : Timestamp(1682503992, 1),
"t" : NumberLong(1)
},
"priorityAtElection" : 50,
"newTermStartDate" : ISODate("2023-04-26T10:13:09.158Z"),
"newTermAppliedDate" : ISODate("2023-04-26T10:13:23.890Z")
},
"members" : [
{
"_id" : 0,
"name" : "mongodb-rs-0.mongodb-rs.default.svc.cluster.local:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 3246,
"optime" : {
"ts" : Timestamp(1682504019, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2023-04-26T10:13:39Z"),
"syncSourceHost" : "mongodb-rs-1.mongodb-rs.default.svc.cluster.local:27017",
"syncSourceId" : 1,
"infoMessage" : "",
"configVersion" : 1,
"configTerm" : 2,
"self" : true,
"lastHeartbeatMessage" : ""
},
{
"_id" : 1,
"name" : "mongodb-rs-1.mongodb-rs.default.svc.cluster.local:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 55,
"optime" : {
"ts" : Timestamp(1682504019, 1),
"t" : NumberLong(2)
},
"optimeDurable" : {
"ts" : Timestamp(1682504019, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2023-04-26T10:13:39Z"),
"optimeDurableDate" : ISODate("2023-04-26T10:13:39Z"),
"lastHeartbeat" : ISODate("2023-04-26T10:13:55.921Z"),
"lastHeartbeatRecv" : ISODate("2023-04-26T10:13:54.904Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"electionTime" : Timestamp(1682503992, 2),
"electionDate" : ISODate("2023-04-26T10:13:12Z"),
"configVersion" : 1,
"configTerm" : 2
},
{
"_id" : 2,
"name" : "mongodb-rs-2.mongodb-rs.default.svc.cluster.local:27017",
"health" : 1,
"state" : 7,
"stateStr" : "ARBITER",
"uptime" : 55,
"lastHeartbeat" : ISODate("2023-04-26T10:13:55.922Z"),
"lastHeartbeatRecv" : ISODate("2023-04-26T10:13:54.932Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"configVersion" : 1,
"configTerm" : 2
}
],
"ok" : 1,
"$clusterTime" : {
"clusterTime" : Timestamp(1682504019, 1),
"signature" : {
"hash" : BinData(0,"KM4OLkjcMxpk7RqlTC2omtRQ0pY="),
"keyId" : NumberLong("7226299616734478340")
}
},
"operationTime" : Timestamp(1682504019, 1)
}
可见,副本集群已成功在k8s上运行。