k8s实践16:使用job控制器备份Mysql容器pod数据库

job配置和简易测试

1.job简单介绍

job也是种控制器,k8s有两种类型的控制器,一种是服务类控制器,比如deployment,deamonset,replicaset等等.一种是工作任务类控制器,job和cronjon就是工作任务类控制器.

job的简易参数介绍

spec.template格式同Pod
RestartPolicy仅支持Never或OnFailure
单个Pod时，默认Pod成功运行后Job即结束.
spec.completions标志Job结束需要成功运行的Pod个数,默认为1,可以理解pod运行的总数.
spec.parallelism标志并行运行的Pod的个数,默认为1,可以理解为同时运行的Pod数量.
spec.activeDeadlineSeconds标志失败Pod的重试最大时间,超过这个时间不会继续重试.
spec.backoffLimit: 指定job失败后进行重试的次数.

2.job简易实例

[root@k8s-node1 job]#cat job1.yaml 
apiVersion: batch/v1
kind: Job
metadata:
  name: pi
spec:
  template:
    metadata:
      name: pi
    spec:
      containers:
      - name: pi
        image: perl
        command: ["perl",  "-Mbignum=bpi", "-wle", "print bpi(2000)"]
      restartPolicy: Never

[root@k8s-node1 job]# kubectl get job
NAME   COMPLETIONS   DURATION   AGE
pi     1/1           8m37s      15m
[root@k8s-node1 job]# kubectl get pod
NAME                             READY   STATUS      RESTARTS   AGE
busybox                          1/1     Running     76         28d
mysql-7c9cbfcdf8-hxlrm           1/1     Running     7          22d
mysql-t-54666b579c-7m5rv         1/1     Running     11         26d
mysql-test-647b8db96b-qdxw6      1/1     Running     10         23d
pi-5gtpz                         0/1     Completed   0          15m
wordpress-pod-74c47cd8dd-dlzvc   1/1     Running     7          22d
[root@k8s-node1 job]# kubectl logs pi-5gtpz
3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989380952572010654858632788659361533818279682303019520353018529689957736225994138912497217752834791315155748572424541506959508295331168617278558890750983817546374649393192550604009277016711390098488240128583616035637076601047101819429555961989467678374494482553797747268471040475346462080466842590694912933136770289891521047521620569660240580381501935112533824300355876402474964732639141992726042699227967823547816360093417216412199245863150302861829745557067498385054945885869269956909272107975093029553211653449872027559602364806654991198818347977535663698074265425278625518184175746728909777727938000816470600161452491921732172147723501414419735685481613611573525521334757418494684385233239073941433345477624168625189835694855620992192221842725502542568876717904946016534668049886272327917860857843838279679766814541009538837863609506800642251252051173929848960841284886269456042419652850222106611863067442786220391949450471237137869609563643719172874677646575739624138908658326459958133904780275901
[root@k8s-node1 job]#

修改配置文件,加上参数测试

[root@k8s-node1 job]# cat job1.yaml 
apiVersion: batch/v1
kind: Job
metadata:
  name: pi
spec:
  completions: 3
  parallelism: 2
  template:
    metadata:
      name: pi
    spec:
      containers:
      - name: pi
        image: perl
        command: ["perl",  "-Mbignum=bpi", "-wle", "print bpi(2000)"]
      restartPolicy: Never

spec.parallelism参数设置了2,因此开始就启动了两个pod

[root@k8s-node1 job]# kubectl get pod
NAME                             READY   STATUS              RESTARTS   AGE
busybox                          1/1     Running             76         28d
mysql-7c9cbfcdf8-hxlrm           1/1     Running             7          22d
mysql-t-54666b579c-7m5rv         1/1     Running             11         26d
mysql-test-647b8db96b-qdxw6      1/1     Running             10         23d
pi-jjpm4                         0/1     ContainerCreating   0          4s
pi-xffsz                         0/1     ContainerCreating   0          4s
wordpress-pod-74c47cd8dd-dlzvc   1/1     Running             7          22d

[root@k8s-node1 job]# kubectl get pod
NAME                             READY   STATUS      RESTARTS   AGE
busybox                          1/1     Running     76         28d
mysql-7c9cbfcdf8-hxlrm           1/1     Running     7          22d
mysql-t-54666b579c-7m5rv         1/1     Running     11         26d
mysql-test-647b8db96b-qdxw6      1/1     Running     10         23d
pi-c4qxs                         0/1     Completed   0          43s
pi-jjpm4                         0/1     Completed   0          55s
pi-xffsz                         0/1     Completed   0          55s
wordpress-pod-74c47cd8dd-dlzvc   1/1     Running     7          22d

3.job备份mysql容器数据库

job在什么场景使用呢?

比如数据库备份

最简单的示例,参考见下:

思路是启用一个job,使用的镜像是mysql:5.7(注意密码必须设置),然后执行命令mysqldump --host=mysql-test -uroot -ppassword --databases t1 >t1.sql.备份MySQL容器pod主机名为mysql-test的数据库(注意mysql-test是svc的名字).

[root@k8s-node1 job]# kubectl get svc,pod
NAME                 TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)         AGE
service/httpd-svc    NodePort    10.254.125.1     <none>        80:8400/TCP     31d
service/kubernetes   ClusterIP   10.254.0.1       <none>        443/TCP         45d
service/mysql        ClusterIP   10.254.209.23    <none>        3306/TCP        23d
service/mysql-t      ClusterIP   10.254.177.63    <none>        3306/TCP        27d
service/mysql-test   ClusterIP   10.254.177.188   <none>        3306/TCP        24d
service/wordpress    NodePort    10.254.88.118    <none>        8080:8425/TCP   23d
NAME                                 READY   STATUS      RESTARTS   AGE
pod/busybox                          1/1     Running     92         29d
pod/mysql-7c9cbfcdf8-hxlrm           1/1     Running     17         23d
pod/mysql-dump-jw5zh                 0/1     Completed   0          80s
pod/mysql-t-54666b579c-7m5rv         1/1     Running     21         27d
pod/mysql-test-647b8db96b-qdxw6      1/1     Running     19         24d
pod/t1-55f6c78557-6xxwd              1/1     Running     0          17m
pod/t2-7f459d454c-wk2zb              1/1     Running     0          17m
pod/wordpress-pod-74c47cd8dd-dlzvc   1/1     Running     12         23d

[root@k8s-node1 job]# cat job2.yaml 
apiVersion: batch/v1
kind: Job
metadata:
  name: mysql-dump
spec:
  template:
    metadata:
      name: mysql-dump
    spec:
      containers:
      - name: mysql-dump
        image: mysql:5.7
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: abc123
        command: ["/bin/sh","-c","mysqldump --host=mysql-test -uroot -ppassword --databases t1 >t1.sql"]
      restartPolicy: Never

测试执行成功.见下:

[root@k8s-node1 storage]# kubectl get job
NAME         COMPLETIONS   DURATION   AGE
mysql-dump   1/1           2s         28m

[root@k8s-node1 storage]# kubectl get pod
NAME                                      READY   STATUS              RESTARTS   AGE
busybox                                   1/1     Running             81         29d
mysql-7c9cbfcdf8-hxlrm                    1/1     Running             7          22d
mysql-dump-p4wn7                          0/1     Completed           0          28m
mysql-t-54666b579c-7m5rv                  1/1     Running             11         27d
mysql-test-647b8db96b-qdxw6               1/1     Running             10         23d
nfs-client-provisioner-5bd47b7669-lzv6j   0/1     ContainerCreating   0          6m38s
wordpress-pod-74c47cd8dd-dlzvc            1/1     Running             7          22d

完美点的示例,把备份的数据解耦出来,加上pvc.

配置pv和pvc,参考见下:

[root@k8s-node1 storage]# cat job-pv1.yaml 
apiVersion: v1
kind: PersistentVolume
metadata:
  name: jobpv1
spec:
  capacity:
    storage: 100Mi
  accessModes:
    - ReadWriteMany
  persistentVolumeReclaimPolicy: Retain
  storageClassName: nfs
  nfs:
    path: /mnt/data/jobpv1
    server: 192.168.174.130
[root@k8s-node1 storage]# kubectl apply -f job-pv1.yaml 
persistentvolume/jobpv1 created
[root@k8s-node1 storage]# kubectl get pv
NAME        CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                STORAGECLASS   REASON   AGE
jobpv1      100Mi      RWX            Retain           Available                        nfs                     7s

pvc

[root@k8s-node1 storage]# cat job-pvc1.yaml 
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
   name: jobpvc1
spec:
   accessModes:
     - ReadWriteMany
   resources:
     requests:
       storage: 100Mi
   storageClassName: nfs
[root@k8s-node1 storage]# kubectl apply -f job-pvc1.yaml 
persistentvolumeclaim/jobpvc1 created
[root@k8s-node1 storage]# kubectl get pvc
NAME         STATUS   VOLUME      CAPACITY   ACCESS MODES   STORAGECLASS   AGE
jobpvc1      Bound    jobpv1      100Mi      RWX            nfs            4s

把pvc使用到job上

[root@k8s-node1 job]# cat job2.yaml 
apiVersion: batch/v1
kind: Job
metadata:
  name: mysql-dump
spec:
  template:
    metadata:
      name: mysql-dump
    spec:
      containers:
      - name: mysql-dump
        image: mysql:5.7
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: abc123
        command: ["/bin/sh","-c","mysqldump --host=mysql-test -uroot -ppassword --databases t1 >/mnt/t1.sql"]
        volumeMounts:
          - name: job-pvc
            mountPath: "/mnt"
      restartPolicy: Never
      volumes:
        - name: job-pvc
          persistentVolumeClaim:
            claimName: jobpvc1

[root@k8s-node1 job]# kubectl apply -f job2.yaml 
job.batch/mysql-dump created
[root@k8s-node1 job]# kubectl get pod
NAME                             READY   STATUS      RESTARTS   AGE
busybox                          1/1     Running     92         29d
mysql-7c9cbfcdf8-hxlrm           1/1     Running     17         23d
mysql-dump-jw5zh                 0/1     Completed   0          3s
mysql-t-54666b579c-7m5rv         1/1     Running     21         27d
mysql-test-647b8db96b-qdxw6      1/1     Running     19         24d
t1-55f6c78557-6xxwd              1/1     Running     0          16m
t2-7f459d454c-wk2zb              1/1     Running     0          15m
wordpress-pod-74c47cd8dd-dlzvc   1/1     Running     12         23d

可以去保存pvc的目录下查看,数据已经备份成功,见下

[root@k8s-node3 jobpv1]# pwd
/mnt/data/jobpv1
[root@k8s-node3 jobpv1]# ls
t1.sql

4.使用cronjob备份

上面用job备份只是一次性执行结束,对于很多备份是需要持续性备份操作的,持续性备份操作,k8s有cronjob.

就用上面的示例修改,未完待续.

来源：51CTO

作者：am2012

链接：https://blog.51cto.com/goome/2460337

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