Even microservices where thought to be used as stateless services, the requirement to persist the data is growing exponentially. Kubernetes and OpenShift facilitate this through persistent volumes and persistent volume claims.

We can use multiple volume plugins to automatically provision these volumes on different storage backends, giving users a way to request those resources without having any knowledge of the underlying infrastructure. This is really cool from a user/developer point of view, but the groups that take care of the PaaS environment would need to implement some backup strategies for the critical data.

If you use EBS for persistent_storage, this post may be useful, as will show you how to create Kubernetes Cron Jobs in OpenShift to automatically create snapshots from the EBS volumes in AWS.

The following repository has all the required components to allow you to perform this operation.

The cronjob-aws-ocp-snap.yaml template creates several objects in OpenShift.

• A custom BuildConfig that will create the required container to run the job from
• A custom ClusterRole that defines the proper permissions to query PVCs in the Cluster
• A ServiceAccount we will use with ‘aws cli’ to perform the snapshots
• A ClusterRoleBinding that maps the ServiceAccount to the ClusterRole
• A CronJob to run the snapshots on a schedule
• A Secret to store the ‘aws cli’ required credentials and config to connect to your AWS account

To deploy this template, run the following:

1. Create a project in which to host your jobs.

   $ oc new-project <project>
   

   ``

2. Instantiate the template

   $ oc process -f cronjob-aws-ocp-snap.yaml \
     -p NAMESPACE="<project name from previous step>" \
     -p AWS_ACCESS_KEY_ID="AWS Access Key ID (base64 format)" \
     -p AWS_SECRET_ACCESS_KEY="WS Secret Access Key ID (base64 format)" \
       -p AWS_REGION="AWS Region where EBS objects reside (base64 format)" \
       -p NSPACE="Namespace where Persistent Volumes are defined (can be ALL)" \
       -p VOL="Persistent Volume Claim name (can be ALL)" \
       | oc create -f-
   

   ``

You should get a CronJob configured in your project:

$ oc get cronjob
NAME                                       SCHEDULE      SUSPEND   ACTIVE    LAST-SCHEDULE
cronjob-ebs-snaphost                       00 23 * * *   False     0         Thu, 23 Nov 2017 23:00:00 +0000

And you will see Jobs coming in the schedule you selected:

$ oc get jobs
NAME                                                  DESIRED   SUCCESSFUL   AGE
cronjob-ebs-snaphost-1511448600                       1         1            21h
cronjob-ebs-snaphost-1511451060                       1         1            20h
cronjob-ebs-snaphost-1511478000                       1         1            13h

If everything works as expected, you would see how the snaphots were created on your Pods' logs:

$ oc logs cronjob-ebs-snaphost-1511478000-lbf67
gogs-data            Bound     pvc-291b545e-bd52-11e7-8ca3-022931080584   10Gi      RWO       gp2       24d
gogs-postgres-data   Bound     pvc-291c0ccc-bd52-11e7-8ca3-022931080584   5Gi       RWO       gp2       24d
jenkins              Bound     pvc-5013abae-b989-11e7-bca0-022931080584   1Gi       RWO       gp2       29d
Creating snapshot for EBS volume  vol-07671c0b8789108a5
{
    "Description": "Automted Snapshot by aws-ocp-snap",
    "Encrypted": false,
    "VolumeId": "vol-07671c0b8789108a5",
    "State": "pending",
    "VolumeSize": 10,
    "StartTime": "2017-11-23T23:00:18.000Z",
    "Progress": "",
    "OwnerId": "715326621454",
    "SnapshotId": "snap-0af5d0fa731641b9f"
}
Creating snapshot for EBS volume  vol-0bde15d87eb1c720c
{
    "Description": "Automted Snapshot by aws-ocp-snap",
    "Encrypted": false,
    "VolumeId": "vol-0bde15d87eb1c720c",
    "State": "pending",
    "VolumeSize": 5,
    "StartTime": "2017-11-23T23:00:18.000Z",
    "Progress": "",
    "OwnerId": "715326621454",
    "SnapshotId": "snap-0750eb9656549568e"
}
Creating snapshot for EBS volume  vol-0264af5d8dffc6b86
{
    "Description": "Automted Snapshot by aws-ocp-snap",
    "Encrypted": false,
    "VolumeId": "vol-0264af5d8dffc6b86",
    "State": "pending",
    "VolumeSize": 1,
    "StartTime": "2017-11-23T23:00:19.000Z",
    "Progress": "",
    "OwnerId": "715326621454",
    "SnapshotId": "snap-0a86551ca6657c328"
}

You should see same info in your AWS console:

Enjoy!