======================
Rsync Database Example
======================

The following example will use the Rsync replication method to periodically
replicate a MySQL database.

First, create the destination Namespace and deploy the ReplicationDestination
object.

.. code:: console

   $ kubectl create ns dest
   $ kubectl create -n dest -f dest.yaml

The ReplicationDestination has the following configuration:

.. code:: yaml

   ---
   apiVersion: volsync.backube/v1alpha1
   kind: ReplicationDestination
   metadata:
     name: database-destination
   spec:
     rsync:
       serviceType: LoadBalancer
       copyMethod: Snapshot
       capacity: 2Gi
       accessModes: [ReadWriteOnce]
       storageClassName: standard-csi
       volumeSnapshotClassName: csi-gce-pd-vsc

A LoadBalancer Service is created by VolSync which will be used by the
ReplicationSource to connect to the destination. Record the service IP address
as it will be used in the ReplicationSource configuration. :ref:`(More
information on LoadBalancer vs ClusterIP) <RsyncServiceExplanation>`

.. code:: console

   $ kubectl get replicationdestination database-destination -n dest --template={{.status.rsync.address}}
   34.133.219.189

Now it is time to deploy our database.

.. code:: console

   $ kubectl create ns source
   $ kubectl create -n source -f examples/source-database

Verify the database is running.

.. code:: console

   $ kubectl get pods -n source
   NAME                    READY   STATUS    RESTARTS   AGE
   mysql-8b9c5c8d8-24w6g   1/1     Running   0          17s

Now create the ReplicationSource items. First, we need the ssh
secret from the destination namespace. :ref:`(SSH Secret copying details) <RsyncKeyCopy>`

.. code:: console

   # Retrieve the Secret from the destination cluster
   $ kubectl get secret -n dest volsync-rsync-dest-src-database-destination -o yaml > /tmp/secret.yaml

   # Remove unnecessary fields
   $ vi /tmp/secret.yaml
   # ^^^ change the namespace to "source"
   # ^^^ remove the owner reference (.metadata.ownerReferences)

   # Insert the Secret into the source cluster
   $ kubectl create -f /tmp/secret.yaml

Using the IP address that relates to the ReplicationDestination that was
recorded earlier. Create a ReplicationSource object:

.. code:: yaml

   ---
   apiVersion: volsync.backube/v1alpha1
   kind: ReplicationSource
   metadata:
     name: database-source
     namespace: source
   spec:
     sourcePVC: mysql-pv-claim
     trigger:
       # Replicate every 5 minutes
       schedule: "*/5 * * * *"
     rsync:
       # The name of the Secret we just created
       sshKeys: volsync-rsync-dest-src-database-destination
       # The LoadBalancer address from the ReplicationDestination
       address: 34.133.219.189
       copyMethod: Clone

Note: You may need to change the ``copyMethod`` to ``Snapshot`` and specify both
a ``storageClassName`` and ``volumeSnapshotClassName``, depending on your CSI
driver's capabilities.

Once the ReplicationSource is created, the initial synchronization should begin.
To verify the replication has completed describe the Replication source.

.. code:: console

   $ kubectl describe ReplicationSource -n source database-source

From the output, the success of the replication can be seen by the following
lines:

.. code:: bash

   Status:
     Conditions:
       Last Transition Time:  2023-08-03T16:07:35Z
       Message:               Reconcile complete
       Reason:                ReconcileComplete
       Status:                True
       Type:                  Reconciled
     Last Sync Duration:      4.511334577s
     Last Sync Time:          2023-08-03T16:09:04Z
     Next Sync Time:          2023-08-03T16:10:00Z

We will modify the source database by creating an additional database in the
mysql pod running in the source namespace.

.. code:: console

   $ kubectl exec --stdin --tty -n source $(kubectl get pods -n source | grep mysql | awk '{print $1}') -- /bin/bash
   $ mysql -u root -p$MYSQL_ROOT_PASSWORD
   > show databases;
   +--------------------+
   | Database           |
   +--------------------+
   | information_schema |
   | mysql              |
   | performance_schema |
   | sys                |
   +--------------------+
   4 rows in set (0.00 sec)


   > create database synced;
   > exit
   $ exit

During the next synchronization iteration, these updates will be replicated to
the destination.

Now the mysql database will be deployed to the destination namespace which will use the
data that has been replicated.

First we need to wait for the next synchronization iteration to complete so the
changes made above to add a new database will be replicated to the destination.

.. code:: console

   $ kubectl get replicationdestination database-destination -n dest --template={{.status.lastSyncTime}}
   2023-08-03T16:29:01Z

When the above has been updated to a newer time as in the example above, then we can proceed to create the
Deployment, Service, PVC, and Secret.

The PVC uses the VolSync volume populator feature and sets the ReplicationDestination
as its dataSourceRef. This will populate the PVC with the latest snapshot contents from the ReplicationDestination.

.. code:: console

   $ kubectl create -n dest -f examples/destination-database/

Validate that the mysql pod is running within the environment.

.. code:: console

   $ kubectl get pods -n dest
   NAME                                           READY   STATUS    RESTARTS   AGE
   mysql-8b9c5c8d8-v6tg6                          1/1     Running   0          38m

Connect to the mysql pod and list the databases to verify the synced database
exists.

.. code:: console

   $ kubectl exec --stdin --tty -n dest $(kubectl get pods -n dest | grep mysql | awk '{print $1}') -- /bin/bash
   $ mysql -u root -p$MYSQL_ROOT_PASSWORD
   > show databases;
   +--------------------+
   | Database           |
   +--------------------+
   | information_schema |
   | mysql              |
   | performance_schema |
   | synced             |
   | sys                |
   +--------------------+
   5 rows in set (0.00 sec)