Document the steps to create a cronjob to run bkps

ref: #818
[noissue]

docs/backup_and_restore/cronjob.md

@@ -0,0 +1,102 @@
+# Scheduling Backups
+
+The current version of Pulp Operator does not provide a way to automate the periodic execution of the backups. The following steps can be used as **an example** of how to create a [k8s Cronjob](https://kubernetes.io/docs/concepts/workloads/controllers/cron-jobs/) to schedule the backup execution.
+
+* create a configmap with the `PulpBackup CR` definition (check the [backup section](/pulp_operator/backup_and_restore/config_running/#backup) for more information on `PulpBackup CR` fields configuration):
+```yaml
+$ kubectl apply -f- <<EOF
+apiVersion: v1
+data:
+  pulp_backup.yaml: |
+    apiVersion: repo-manager.pulpproject.org/v1beta2
+    kind: PulpBackup
+    metadata:
+      name: pulpbackup
+    spec:
+      deployment_name: pulp
+      backup_storage_class: standard
+kind: ConfigMap
+metadata:
+  name: pulpbackup-cr
+EOF
+```
+
+* for this example, we will create a new `ServiceAccount` that will be used by `Cronjob` pods. It is not a required step, you can skip it if your environment already has a `ServiceAccount` with the permissions to modify `PulpBackup` resources:
+```yaml
+$ kubectl apply -f-<<EOF
+---
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: pulpbackup
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: pulpbackup
+rules:
+- apiGroups: ["repo-manager.pulpproject.org"]
+  resources: ["pulpbackups"]
+  verbs: ["get", "watch", "list","create","patch","update","delete"]
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: pulpbackup
+subjects:
+- kind: ServiceAccount
+  name: pulpbackup
+roleRef:
+  kind: Role
+  name: pulpbackup
+  apiGroup: rbac.authorization.k8s.io
+EOF
+```
+
+* create the `k8s Cronjob` to run the backups:
+```yaml
+$ kubectl apply -f-<<EOF
+apiVersion: batch/v1
+kind: CronJob
+metadata:
+  name: pulpbackup
+spec:
+  schedule: "00 2 * * *"
+  successfulJobsHistoryLimit: 1
+  failedJobsHistoryLimit: 1
+  jobTemplate:
+    spec:
+      template:
+        spec:
+          containers:
+          - name: bkp
+            image: bitnami/kubectl:latest
+            imagePullPolicy: IfNotPresent
+            volumeMounts:
+            - name: pulpbackup-cr
+              mountPath: /tmp/pulp_backup.yaml
+              subPath: pulp_backup.yaml
+            command:
+            - /bin/sh
+            - -c
+            args:
+            - "kubectl apply -f /tmp/pulp_backup.yaml && kubectl wait --for condition=BackupComplete --timeout=600s -f /tmp/pulp_backup.yaml ; kubectl delete -f /tmp/pulp_backup.yaml"
+          restartPolicy: Never
+          serviceAccountName: pulpbackup
+          volumes:
+          - name: pulpbackup-cr
+            configMap:
+              name: pulpbackup-cr
+EOF
+```
+
+In this example, the job:
+
+* will be triggered every day at *2:00 AM* (`schedule: 00 2 * * *`)
+* will keep `1` successful and/or `1` failed job (`successfulJobsHistoryLimit: 1, failedJobsHistoryLimit: 1`)
+* will be considered failed if the backup does not finish in `10minutes` (`--timeout=600s`)
+* will run with the previously created *pulpbackup* `ServiceAccount` (`serviceAccountName: pulpbackup`)
+
+
+!!! note
+    Don't forget to rotate the backup files from time to time to avoid filling up the storage.

mkdocs.yml

@@ -60,6 +60,7 @@ nav:
   - Backup and Restore:
       - Overview: backup_and_restore/overview.md
       - Configuring and Running: backup_and_restore/config_running.md
+      - Scheduling backups: backup_and_restore/cronjob.md
   - Changelog: CHANGES.md
   - FAQ: faq.md
   - Troubleshooting: