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Database Scheduled Snapshots

This tutorial will show you how to use KubeDB to take scheduled snapshot of a MongoDB database.

Before You Begin

At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using Minikube.
Now, install KubeDB cli on your workstation and KubeDB operator in your cluster following the steps here.
StorageClass is required to run KubeDB. Check the available StorageClass in cluster.
To keep things isolated, this tutorial uses a separate namespace called demo throughout this tutorial. Run the following command to prepare your cluster for this tutorial:
```
$ kubectl create ns demo
namespace/demo created
```

Note: The yaml files used in this tutorial are stored in docs/examples/mongodb folder in GitHub repository kubedb/docs.

Scheduled Backups

KubeDB supports taking periodic backups for a database using a cron expression. KubeDB operator will launch a Job periodically that runs the mongodump command and uploads the output bson file to various cloud providers S3, GCS, Azure, OpenStack Swift and/or locally mounted volumes using osm.

In this tutorial, snapshots will be stored in a Google Cloud Storage (GCS) bucket. To do so, a secret is needed that has the following 2 keys:

Key	Description
`GOOGLE_PROJECT_ID`	`Required`. Google Cloud project ID
`GOOGLE_SERVICE_ACCOUNT_JSON_KEY`	`Required`. Google Cloud service account json key

$ echo -n '<your-project-id>' > GOOGLE_PROJECT_ID
$ mv downloaded-sa-json.key > GOOGLE_SERVICE_ACCOUNT_JSON_KEY
$ kubectl create secret generic mg-snap-secret -n demo \
    --from-file=./GOOGLE_PROJECT_ID \
    --from-file=./GOOGLE_SERVICE_ACCOUNT_JSON_KEY
secret "mg-snap-secret" created

$ kubectl get secret mg-snap-secret -n demo -o yaml
apiVersion: v1
data:
  GOOGLE_PROJECT_ID: PHlvdXItcHJvamVjdC1pZD4=
  GOOGLE_SERVICE_ACCOUNT_JSON_KEY: ewogICJ0eXBlIjogInNlcnZpY2VfYWNjb3V...9tIgp9Cg==
kind: Secret
metadata:
  creationTimestamp: 2018-02-02T10:02:09Z
  name: mg-snap-secret
  namespace: demo
  resourceVersion: "48679"
  selfLink: /api/v1/namespaces/demo/secrets/mg-snap-secret
  uid: 220a7c60-0800-11e8-946f-080027c05a6e
type: Opaque

To learn how to configure other storage destinations for Snapshots, please visit here. Now, create the MongoDB object with scheduled snapshot.

apiVersion: kubedb.com/v1alpha1
kind: MongoDB
metadata:
  name: mgo-scheduled
  namespace: demo
spec:
  version: "3.4-v3"
  storage:
    storageClassName: "standard"
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
  backupSchedule:
    cronExpression: "@every 1m"
    storageSecretName: mg-snap-secret
    gcs:
      bucket: kubedb-qa

$ kubedb create -f https://github.com/kubedb/docs/raw/v0.13.0-rc.0/docs/examples/mongodb/snapshot/demo-4.yaml
mongodb.kubedb.com/mgo-scheduled created

It is also possible to add backup scheduler to an existing MongoDB. You just have to edit the MongoDB CRD and add below spec:

$ kubedb edit mg {db-name} -n demo
spec:
  backupSchedule:
    cronExpression: '@every 1m'
    gcs:
      bucket: kubedb-qa
    storageSecretName: mg-snap-secret

Once the spec.backupSchedule is added, KubeDB operator will create a new Snapshot object on each tick of the cron expression. This triggers KubeDB operator to create a Job as it would for any regular instant backup process. You can see the snapshots as they are created using kubedb get snap command.

$ kubedb get snap -n demo
NAME                            DATABASENAME    STATUS      AGE
mgo-scheduled-20180924-112630   mgo-scheduled   Succeeded   3m
mgo-scheduled-20180924-112741   mgo-scheduled   Succeeded   2m
mgo-scheduled-20180924-112841   mgo-scheduled   Succeeded   1m
mgo-scheduled-20180924-112941   mgo-scheduled   Running     8s

you should see the output of the mongodump command for each snapshot stored in the GCS bucket.

snapshot-console

From the above image, you can see that the snapshot output is stored in a folder called {bucket}/kubedb/{namespace}/{mongodb-object}/{snapshot}/.

Remove Scheduler

To remove scheduler, edit the MongoDB object to remove spec.backupSchedule section.

$ kubedb edit mg mgo-scheduled -n demo
apiVersion: kubedb.com/v1alpha1
kind: MongoDB
metadata:
  name: mgo-scheduled
  namespace: demo
  ...
spec:
# backupSchedule:
#   cronExpression: '@every 1m'
#   gcs:
#     bucket: kubedb-qa
#   storageSecretName: mg-snap-secret
  databaseSecret:
    secretName: mgo-scheduled-auth
  storage:
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
    storageClassName: standard
  version: 3.4-v3
status:
  creationTime: 2018-02-02T10:46:18Z
  phase: Running

Customizing `backupSchedule`

You can customize pod template spec and volume claim spec for the backup jobs by customizing backupSchedule section.

Some common customization examples are shown below:

Specify PVC Template:

Backup jobs use temporary storage to hold dump files before it can be uploaded to cloud backend. By default, KubeDB reads storage specification from spec.storage section of database crd and creates a PVC with similar specification for backup job. However, if you want to specify a custom PVC template, you can do it through spec.backupSchedule.podVolumeClaimSpec field. This is particularly helpful when you want to use different storageclass for backup jobs and the database.

apiVersion: kubedb.com/v1alpha1
kind: MongoDB
metadata:
  name: mgo-scheduled
  namespace: demo
spec:
  version: "3.4-v3"
  storage:
    storageClassName: "standard"
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
  backupSchedule:
    cronExpression: "@every 1m"
    storageSecretName: mg-snap-secret
    gcs:
      bucket: kubedb
    podVolumeClaimSpec:
      storageClassName: "standard"
      accessModes:
      - ReadWriteOnce
      resources:
        requests:
          storage: 1Gi # make sure size is larger or equal than your database size

Specify Resources for Backup Jobs:

You can specify resources for backup jobs through spec.backupSchedule.podTemplate.spec.resources field.

apiVersion: kubedb.com/v1alpha1
kind: MongoDB
metadata:
  name: mgo-scheduled
  namespace: demo
spec:
  version: "3.4-v3"
  storage:
    storageClassName: "standard"
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
  backupSchedule:
    cronExpression: "@every 1m"
    storageSecretName: mg-snap-secret
    gcs:
      bucket: kubedb
    podTemplate:
      spec:
        resources:
          requests:
            memory: "64Mi"
            cpu: "250m"
          limits:
            memory: "128Mi"
            cpu: "500m"

Provide Annotations for Backup Jobs:

If you need to add some annotations to backup jobs, you can specify those in spec.backupSchedule.podTemplate.controller.annotations. You can also specify annotations for the pod created by backup jobs in spec.backupSchedule.podTemplate.annotations field.

apiVersion: kubedb.com/v1alpha1
kind: MongoDB
metadata:
  name: mgo-scheduled
  namespace: demo
spec:
  version: "3.4-v3"
  storage:
    storageClassName: "standard"
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
  backupSchedule:
    cronExpression: "@every 1m"
    storageSecretName: mg-snap-secret
    gcs:
      bucket: kubedb
    podTemplate:
      annotations:
        passMe: ToBackupJobPod
      controller:
        annotations:
          passMe: ToBackupJob

Pass Arguments to Backup Jobs:

KubeDB allows users to pass extra arguments for backup jobs. You can provide these arguments via spec.backupSchedule.podTemplate.spec.args field of a Snapshot crd.

apiVersion: kubedb.com/v1alpha1
kind: MongoDB
metadata:
  name: mgo-scheduled
  namespace: demo
spec:
  version: "3.4-v3"
  storage:
    storageClassName: "standard"
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
  backupSchedule:
    cronExpression: "@every 1m"
    storageSecretName: mg-snap-secret
    gcs:
      bucket: kubedb
    podTemplate:
      spec:
        args:
        - --extra-args-to-backup-command

Cleaning up

To cleanup the Kubernetes resources created by this tutorial, run:

kubectl patch -n demo mg/mgo-scheduled -p '{"spec":{"terminationPolicy":"WipeOut"}}' --type="merge"
kubectl delete -n demo mg/mgo-scheduled

kubectl patch -n demo drmn/mgo-scheduled -p '{"spec":{"wipeOut":true}}' --type="merge"
kubectl delete -n demo drmn/mgo-scheduled

kubectl delete ns demo

Next Steps

See the list of supported storage providers for snapshots here.
Initialize MongoDB with Script.
Initialize MongoDB with Snapshot.
Monitor your MongoDB database with KubeDB using out-of-the-box CoreOS Prometheus Operator.
Monitor your MongoDB database with KubeDB using out-of-the-box builtin-Prometheus.
Use private Docker registry to deploy MongoDB with KubeDB.
Detail concepts of MongoDB object.
Detail concepts of MongoDBVersion object.
Want to hack on KubeDB? Check our contribution guidelines.

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