cron - 在 Openshift 上的应用程序中运行 cron 作业的最佳实践？

Question

我想对部署在 Openshift 中的 postgres 数据库运行一个简单的备份。运行 cron 作业的最佳实践是什么？由于 systemd 在容器上不可用并且只能通过 hack 启用，我宁愿使用“更清洁”的方法。除了 cronie 或 systemd 计时器单元，还有哪些选项？似乎可以在 earlier 中启用 cron Openshift 版本，但 Openshift v4.x 不再支持此功能，文档仅提及 Kubernetes Cron Jobs 对象。

Answer 1

这是我使用的:

• 具有相同镜像的专用 Pod(确保 db dump 客户端可用)和用于备份的 PVC 挂载
• 带有备份脚本的 ConfigMap
• 经常运行该 pod 的 Cronjob

以下是一些示例 list :

PVC:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: database-bkp
  namespace: database
    annotations:
    volume.beta.kubernetes.io/storage-class: "storage-class-name"
spec:
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 1Gi

CM:

apiVersion: v1
kind: ConfigMap
metadata:
  name: psqldump
  namespace: database
  labels:
    job-name: db-backup
data:
  psqldump.sh: |
    #!/bin/bash
    DBS=$(psql -xl |awk /^Name/'{print $NF}')
    for DB in ${DBS}; do
      SCHEMAS=$(psql -d ${DB} -xc "\dn" |awk /^Name/'{print $NF}')
      for SCHEMA in ${SCHEMAS}; do
        echo "Dumping database '${DB}' from Schema '${SCHEMA}' into ${BACKUPDIR}/${PGHOST}_${SCHEMA}_${DB}_${ENVMNT}_$(date -I).sql"
        pg_dump -n "${SCHEMA}" ${DB} > ${BACKUPDIR}/${PGHOST}_${SCHEMA}_${DB}_${ENVMNT}_$(date -I).sql
      done
    done
    echo "Deleting dumps older than ${RETENTION} days"
    find ${BACKUPDIR} -name "*.sql" -mtime +${RETENTION} -exec rm -rf {} \;

CronJob:

apiVersion: v1
kind: Template
metadata:
  name: postgres-backup
  namespace: database
objects:
- kind: CronJob
  apiVersion: batch/v1beta1
  metadata:
    name: postgres-backup
    namespace: database
  spec:
    schedule: "0 3 * * *"
    successfulJobsHistoryLimit: 1
    jobTemplate:
      spec:
        template:
          metadata:
            namespace: database
          spec:
            containers:
            - name: postgres-dbbackup
              image: "postgres:11"
              env:
              - name: PGHOST
                value: "${_PGHOST}"
              - name: PGUSER
                value: "${_PGUSER}"
              - name: RETENTION
                value: "${_RETENTION}"
              - name: BACKUPDIR
                value: "${_BACKUPDIR}"
              command: ["/bin/bash", "-c", "/usr/local/bin/psqldump.sh"]
              volumeMounts:
              - mountPath: /usr/local/bin
                name: psqldump-volume
              - mountPath: /backup
                name: backup-volume
            volumes:
              - name: psqldump-volume
                configMap:
                  name: psqldump
                  defaultMode: 0755
              - name: backup-volume
                persistentVolumeClaim:
                  claimName: database-bkp
            restartPolicy: Never
parameters:
  - name: _PGHOST
    value: postgres
  - name: _PGUSER
    value: postgres
  - name: _RETENTION
    value: "30"
  - name: _BACKUPDIR
    value: "/backup"

PGHOST 是数据库的 pod 名称。如果您有专门的备份用户和密码，请相应地导出环境变量 PGUSER 和 PGPASS