Backup and Restore PostgreSQL database using Stash

Stash 0.9.0+ supports backup and restoration of PostgreSQL databases. This guide will show you how you can backup and restore your PostgreSQL database with Stash.

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.
• Install Stash in your cluster following the steps here.
• Install PostgreSQL addon for Stash following the steps here
• Install KubeDB in your cluster following the steps here. This step is optional. You can deploy your database using any method you want. We are using KubeDB because KubeDB simplifies many of the difficult or tedious management tasks of running a production grade databases on private and public clouds.
• If you are not familiar with how Stash backup and restore PostgreSQL databases, please check the following guide here:

You have to be familiar with following custom resources:

• AppBinding
• Function
• Task
• BackupConfiguration
• RestoreSession

To keep things isolated, we are going to use a separate namespace called demo throughout this tutorial. Create demo namespace if you haven’t created yet.

$ kubectl create ns demo
namespace/demo created

Note: YAML files used in this tutorial are stored here.

Backup PostgreSQL

This section will demonstrate how to backup PostgreSQL database. Here, we are going to deploy a PostgreSQL database using KubeDB. Then, we are going to backup this database into a GCS bucket. Finally, we are going to restore the backed up data into another PostgreSQL database.

Deploy Sample PostgresQL Database

Let’s deploy a sample PostgreSQL database and insert some data into it.

Create Postgres CRD:

Below is the YAML of a sample Postgres crd that we are going to create for this tutorial:

apiVersion: kubedb.com/v1alpha1
kind: Postgres
metadata:
  name: sample-postgres
  namespace: demo
spec:
  version: "10.14"
  storageType: Durable
  storage:
    storageClassName: "standard"
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
  terminationPolicy: Delete

Create the above Postgres crd,

$ kubectl apply -f https://github.com/stashed/postgres/raw/10.14.0-v4/docs/examples/backup/postgres.yaml
postgres.kubedb.com/sample-postgres created

KubeDB will deploy a PostgreSQL database according to the above specification. It will also create the necessary secrets and services to access the database.

Let’s check if the database is ready to use,

$ kubectl get pg -n demo sample-postgres
NAME              VERSION      STATUS    AGE
sample-postgres   10.14        Running   3m11s

The database is Running. Verify that KubeDB has created a Secret and a Service for this database using the following commands,

$ kubectl get secret -n demo -l=kubedb.com/name=sample-postgres
NAME                   TYPE     DATA   AGE
sample-postgres-auth   Opaque   2      27h

$ kubectl get service -n demo -l=kubedb.com/name=sample-postgres
NAME                       TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
sample-postgres            ClusterIP   10.106.147.155   <none>        5432/TCP   22h
sample-postgres-replicas   ClusterIP   10.96.231.122    <none>        5432/TCP   22h

Here, we have to use service sample-postgres and secret sample-postgres-auth to connect with the database. KubeDB creates an AppBinding crd that holds the necessary information to connect with the database.

Verify AppBinding:

Verify that the AppBinding has been created successfully using the following command,

$ kubectl get appbindings -n demo
NAME              AGE
sample-postgres   20m

Let’s check the YAML of the above AppBinding,

$ kubectl get appbindings -n demo sample-postgres -o yaml

apiVersion: appcatalog.appscode.com/v1alpha1
kind: AppBinding
metadata:
  creationTimestamp: "2019-09-25T12:18:54Z"
  generation: 1
  labels:
    app.kubernetes.io/component: database
    app.kubernetes.io/instance: sample-postgres
    app.kubernetes.io/managed-by: kubedb.com
    app.kubernetes.io/name: postgres
    app.kubernetes.io/version: 10.14
    kubedb.com/kind: Postgres
    kubedb.com/name: sample-postgres
  name: sample-postgres
  namespace: demo
spec:
  clientConfig:
    service:
      name: sample-postgres
      path: /
      port: 5432
      query: sslmode=disable
      scheme: postgresql
  secret:
    name: sample-postgres-auth
  type: kubedb.com/postgres
  version: "10.14"

Stash uses the AppBinding crd to connect with the target database. It requires the following two fields to set in AppBinding’s Spec section.

• spec.clientConfig.service.name specifies the name of the service that connects to the database.
• spec.secret specifies the name of the secret that holds necessary credentials to access the database.
• spec.type specifies the types of the app that this AppBinding is pointing to. KubeDB generated AppBinding follows the following format: <app group>/<app resource type>.

Creating AppBinding Manually:

If you deploy PostgreSQL database without KubeDB, you have to create the AppBinding crd manually in the same namespace as the service and secret of the database.

The following YAML shows a minimal AppBinding specification that you have to create if you deploy PostgreSQL database without KubeDB.

apiVersion: appcatalog.appscode.com/v1alpha1
kind: AppBinding
metadata:
  name: my-custom-appbinding
  namespace: my-database-namespace
spec:
  clientConfig:
    service:
      name: my-database-service
      port: 5432
      scheme: postgresql
  secret:
    name: my-database-credentials-secret
  # type field is optional. you can keep it empty.
  # if you keep it empty then the value of TARGET_APP_RESOURCE variable
  # will be set to "appbinding" during auto-backup.
  type: postgres

Insert Sample Data:

Now, we are going to exec into the database pod and create some sample data. At first, find out the database pod using the following command,

$ kubectl get pods -n demo --selector="kubedb.com/name=sample-postgres"
NAME                READY   STATUS    RESTARTS   AGE
sample-postgres-0   1/1     Running   0          8m58s

Now, let’s exec into the pod and create a table,

$ kubectl exec -it -n demo sample-postgres-0 sh
# login as "postgres" superuser.
/ # psql -U postgres
psql (10.14)
Type "help" for help.

# list available databases
postgres=# \l
                                 List of databases
   Name    |  Owner   | Encoding |  Collate   |   Ctype    |   Access privileges
-----------+----------+----------+------------+------------+-----------------------
 postgres  | postgres | UTF8     | en_US.utf8 | en_US.utf8 |
 template0 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
(3 rows)

# connect to "postgres" database
postgres=# \c postgres
You are now connected to database "postgres" as user "postgres".

# create a table
postgres=# CREATE TABLE COMPANY( NAME TEXT NOT NULL, EMPLOYEE INT NOT NULL);
CREATE TABLE

# list tables
postgres=# \d
          List of relations
 Schema |  Name   | Type  |  Owner
--------+---------+-------+----------
 public | company | table | postgres
(1 row)

# quit from the database
postgres=# \q

# exit from the pod
/ # exit

Now, we are ready to backup this sample database.

Prepare Backend

We are going to store our backed up data into a GCS bucket. At first, we need to create a secret with GCS credentials then we need to create a Repository crd. If you want to use a different backend, please read the respective backend configuration doc from here.

Create Storage Secret:

Let’s create a secret called gcs-secret with access credentials to our desired GCS bucket,

$ echo -n 'changeit' > RESTIC_PASSWORD
$ echo -n '<your-project-id>' > GOOGLE_PROJECT_ID
$ cat downloaded-sa-json.key > GOOGLE_SERVICE_ACCOUNT_JSON_KEY
$ kubectl create secret generic -n demo gcs-secret \
    --from-file=./RESTIC_PASSWORD \
    --from-file=./GOOGLE_PROJECT_ID \
    --from-file=./GOOGLE_SERVICE_ACCOUNT_JSON_KEY
secret/gcs-secret created

Create Repository:

Now, crete a Repository using this secret. Below is the YAML of Repository crd we are going to create,

apiVersion: stash.appscode.com/v1alpha1
kind: Repository
metadata:
  name: gcs-repo
  namespace: demo
spec:
  backend:
    gcs:
      bucket: appscode-qa
      prefix: /demo/postgres/sample-postgres
    storageSecretName: gcs-secret

Let’s create the Repository we have shown above,

$ kubectl apply -f https://github.com/stashed/postgres/raw/10.14.0-v4/docs/examples/backup/repository.yaml
repository.stash.appscode.com/gcs-repo created

Now, we are ready to backup our database to our desired backend.

Backup

We have to create a BackupConfiguration targeting respective AppBinding crd of our desired database. Stash will create a CronJob to periodically backup the database.

Create BackupConfiguration:

Below is the YAML for BackupConfiguration crd to backup the sample-postgres database we have deployed earlier.,

apiVersion: stash.appscode.com/v1beta1
kind: BackupConfiguration
metadata:
  name: sample-postgres-backup
  namespace: demo
spec:
  schedule: "*/5 * * * *"
  task:
    name: postgres-backup-10.14.0-v4
  repository:
    name: gcs-repo
  target:
    ref:
      apiVersion: appcatalog.appscode.com/v1alpha1
      kind: AppBinding
      name: sample-postgres
  retentionPolicy:
    keepLast: 5
    prune: true

Here,

• spec.schedule specifies that we want to backup the database at 5 minutes interval.
• spec.task.name specifies the name of the task crd that specifies the necessary Function and their execution order to backup a PostgreSQL database.
• spec.repository.name specifies the name of the Repository crd the holds the backend information where the backed up data will be stored.
• spec.target.ref refers to the AppBinding crd that was created for sample-postgres database.
• spec.retentionPolicy specifies the policy to follow for cleaning old snapshots.

Let’s create the BackupConfiguration crd we have shown above,

$ kubectl apply -f https://github.com/stashed/postgres/raw/10.14.0-v4/docs/examples/backup/backupconfiguration.yaml
backupconfiguration.stash.appscode.com/sample-postgres-backup created

Verify CronJob:

If everything goes well, Stash will create a CronJob with the schedule specified in spec.schedule field of BackupConfiguration crd.

Verify that the CronJob has been created using the following command,

$ kubectl get cronjob -n demo
NAME                     SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE
sample-postgres-backup   */5 * * * *   False     0        <none>          61s

Wait for BackupSession:

The sample-postgres-backup CronJob will trigger a backup on each scheduled slot by creating a BackupSession crd.

Wait for a schedule to appear. Run the following command to watch BackupSession crd,

$ watch -n 1 kubectl get backupsession -n demo -l=stash.appscode.com/backup-configuration=sample-postgres-backup

Every 1.0s: kubectl get backupsession -n demo  -l=stash.appscode.com/backup-configuration=sample-postgres-backup           workstation: Thu Aug  1 18:29:19 2019

NAME                                INVOKER-TYPE          INVOKER-NAME             PHASE       AGE
sample-postgres-backup-1560350521   BackupConfiguration   sample-postgres-backup   Succeeded   5m45s

We can see above that the backup session has succeeded. Now, we are going to verify that the backed up data has been stored in the backend.

Note: Backup CronJob creates BackupSession crds with the following label stash.appscode.com/backup-configuration=<BackupConfiguration crd name>. We can use this label to watch only the BackupSession of our desired BackupConfiguration.

Verify Backup:

Once a backup is complete, Stash will update the respective Repository crd to reflect the backup completion. Check that the repository gcs-repo has been updated by the following command,

$ kubectl get repository -n demo gcs-repo
NAME       INTEGRITY   SIZE        SNAPSHOT-COUNT   LAST-SUCCESSFUL-BACKUP   AGE
gcs-repo   true        3.441 KiB   1                31s                      17m

Now, if we navigate to the GCS bucket, we are going to see backed up data has been stored in demo/postgres/sample-postgres directory as specified by spec.backend.gcs.prefix field of Repository crd.

Note: Stash keeps all the backed up data encrypted. So, data in the backend will not make any sense until they are decrypted.

Restore PostgreSQL

Now, we are going to restore the database from the backup we have taken in the previous section. We are going to deploy a new database and initialize it from the backup.

Stop Taking Backup of the Old Database:

At first, let’s stop taking any further backup of the old database so that no backup is taken during the restore process. We are going to pause the BackupConfiguration crd that we had created to backup the sample-postgres database. Then, Stash will stop taking any further backup for this database.

Let’s pause the sample-postgres-backup BackupConfiguration,

$ kubectl patch backupconfiguration -n demo sample-postgres-backup --type="merge" --patch='{"spec": {"paused": true}}'
backupconfiguration.stash.appscode.com/sample-postgres-backup patched

Now, wait for a moment. Stash will pause the BackupConfiguration. Verify that the BackupConfiguration has been paused,

$ kubectl get backupconfiguration -n demo sample-postgres-backup
NAME                    TASK                        SCHEDULE      PAUSED   AGE
sample-postgres-backup  postgres-backup-10.14.0-v4      */5 * * * *   true     26m

Notice the PAUSED column. Value true for this field means that the BackupConfiguration has been paused.

Deploy Restored Database:

Now, we have to deploy the restored database similarly as we have deployed the original sample-psotgres database. However, this time there will be the following differences:

• We have to use the same secret that was used in the original database. We are going to specify it using spec.databaseSecret field.
• We have to specify spec.init section to tell KubeDB that we are going to use Stash to initialize this database from backup. KubeDB will keep the database phase to Initializing until Stash finishes its initialization.

Below is the YAML for Postgres crd we are going deploy to initialize from backup,

apiVersion: kubedb.com/v1alpha1
kind: Postgres
metadata:
  name: restored-postgres
  namespace: demo
spec:
  version: "10.14"
  storageType: Durable
  databaseSecret:
    secretName: sample-postgres-auth # use same secret as original the database
  storage:
    storageClassName: "standard"
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
  init:
    stashRestoreSession:
      name: sample-postgres-restore
  terminationPolicy: Delete

Here,

• spec.databaseSecret.secretName specifies the name of the database secret of the original database. You must use the same secret in the restored database. Otherwise, the restore process will fail.
• spec.init.stashRestoreSession.name specifies the RestoreSession crd name that we are going to use to restore this database.

Let’s create the above database,

$ kubectl apply -f https://github.com/stashed/postgres/raw/10.14.0-v4/docs/examples/restore/restored-postgres.yaml
postgres.kubedb.com/restored-postgres created

If you check the database status, you will see it is stuck in Initializing state.

$ kubectl get pg -n demo restored-postgres
NAME                VERSION      STATUS         AGE
restored-postgres   10.14        Initializing   3m21s

Create RestoreSession:

Now, we need to create a RestoreSession crd pointing to the AppBinding for this restored database.

Check AppBinding has been created for the restored-postgres database using the following command,

$ kubectl get appbindings -n demo restored-postgres
NAME                AGE
restored-postgres   9m59s

If you are not using KubeDB to deploy database, create the AppBinding manually.

Below is the YAML for the RestoreSession crd that we are going to create to restore backed up data into restored-postgres database.

apiVersion: stash.appscode.com/v1beta1
kind: RestoreSession
metadata:
  name: sample-postgres-restore
  namespace: demo
  labels:
    kubedb.com/kind: Postgres # this label is mandatory if you are using KubeDB to deploy the database.
spec:
  task:
    name: postgres-restore-10.14.0-v4
  repository:
    name: gcs-repo
  target:
    ref:
      apiVersion: appcatalog.appscode.com/v1alpha1
      kind: AppBinding
      name: restored-postgres
  rules:
    - snapshots: [latest]

Here,

• metadata.labels specifies a kubedb.com/kind: Postgres label that is used by KubeDB to watch this RestoreSession.
• spec.task.name specifies the name of the Task crd that specifies the Functions and their execution order to restore a PostgreSQL database.
• spec.repository.name specifies the Repository crd that holds the backend information where our backed up data has been stored.
• spec.target.ref refers to the AppBinding crd for the restored-postgres database where the backed up data will be restored.
• spec.rules specifies that we are restoring from the latest backup snapshot of the original database.

Warning: Label kubedb.com/kind: Postgres is mandatory if you are using KubeDB to deploy the database. Otherwise, the database will be stuck in Initializing state.

Let’s create the RestoreSession crd we have shown above,

$ kubectl apply -f https://github.com/stashed/postgres/raw/10.14.0-v4/docs/examples/restore/restoresession.yaml
restoresession.stash.appscode.com/sample-postgres-restore created

Once, you have created the RestoreSession crd, Stash will create a restore job. We can watch the RestoreSession phase to check if the restore process has succeeded or not.

Run the following command to watch RestoreSession phase,

$ watch -n 1 kubectl get restoresession -n demo sample-postgres-restore

Every 1.0s: kubectl get restoresession -n demo sample-postgres-restore           workstation: Thu Aug  1 18:29:19 2019
NAME                      REPOSITORY-NAME   PHASE       AGE
sample-postgres-restore   gcs-repo          Succeeded   2m4s

So, we can see from the output of the above command that the restore process succeeded.

Verify Restored Data:

In this section, we are going to verify that the desired data has been restored successfully. We are going to connect to the database and check whether the table we had created in the original database is restored or not.

At first, check if the database has gone into Running state by the following command,

$ kubectl get pg -n demo restored-postgres
NAME                VERSION      STATUS    AGE
restored-postgres   10.14        Running   2m16s

Now, find out the database pod by the following command,

$ kubectl get pods -n demo --selector="kubedb.com/name=restored-postgres"
NAME                  READY   STATUS    RESTARTS   AGE
restored-postgres-0   1/1     Running   0          3m15s

Now, exec into the database pod and list available tables,

$ kubectl exec -it -n demo restored-postgres-0 sh
# login as "postgres" superuser.
/ # psql -U postgres
psql (10.14)
Type "help" for help.

# list available databases
postgres=# \l
                                 List of databases
   Name    |  Owner   | Encoding |  Collate   |   Ctype    |   Access privileges
-----------+----------+----------+------------+------------+-----------------------
 postgres  | postgres | UTF8     | en_US.utf8 | en_US.utf8 |
 template0 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
(3 rows)

# connect to "postgres" database
postgres=# \c postgres
You are now connected to database "postgres" as user "postgres".

# check the table we had created in the original database has been restored here
postgres=# \d
          List of relations
 Schema |  Name   | Type  |  Owner
--------+---------+-------+----------
 public | company | table | postgres
(1 row)

# quit from the database
postgres=# \q

# exit from the pod
/ # exit

So, from the above output, we can see the table company that we had created in the original database sample-postgres is restored in the restored database restored-postgres.

Cleanup

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

kubectl delete backupconfiguration -n demo sample-postgres-backup
kubectl delete restoresession -n demo sample-postgres-restore
kubectl delete pg -n demo restored-postgres
kubectl delete pg -n demo sample-postgres