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Example DB as a Service

This demo will showcase Sveltos' ability to dynamically provision PostgreSQL databases on demand.

By simply labeling a managed cluster with postgres=required, Sveltos will automatically deploy a dedicated PostgreSQL database within the services managed cluster. This database will then be made accessible to the requesting cluster, ensuring seamless integration and data access.

Note

This tutorial assumes that each managed cluster is in a different namespace.

Lab Setup

A Civo cluster serves as the management cluster. Another Civo cluster, labeled type=services, is dedicated to automatic Postgres DB deployment by Sveltos.

Postgres DB will be deployed using Cloudnative-pg.

Sveltos: Deploy Cloudnative-pg

Step 1: Install Sveltos on Management Cluster

For this tutorial, we will install Sveltos in the management cluster. Sveltos installation details can be found here.

helm install cert-manager jetstack/cert-manager --namespace cert-manager --create-namespace --version v1.16.1 --set crds.enabled=true
helm install projectsveltos projectsveltos/projectsveltos -n projectsveltos --create-namespace

Add the label type=mgmt to the management cluster:

kubectl label sveltoscluster -n mgmt mgmt type=mgmt

Granting Extra RBAC

For this demo, Sveltos needs to be granted extra permission:

kubectl patch clusterrole addon-controller-role-extra -p '{
  "rules": [
    {               
      "apiGroups": [
        ""
      ],            
      "resources": [ 
        "configmaps",
        "secrets"
      ],        
      "verbs": [
        "*"
      ]
    }
  ]
}'

Step 2: Register Clusters with Sveltos

Using Civo UI, download the Kubeconfigs, then:

kubectl create ns managed-services
sveltosctl register cluster --namespace=managed-services --cluster=cluster --kubeconfig=<managed cluster kubeconfig> --labels=type=services

Verify clusters were successfully registered:

kubectl get sveltoscluster -A --show-labels
NAMESPACE          NAME      READY   VERSION        LABELS
mgmt               mgmt      true    v1.29.2+k3s1   projectsveltos.io/k8s-version=v1.29.2,sveltos-agent=present,type=mgmt
managed-services   cluster   true    v1.29.8+k3s1   projectsveltos.io/k8s-version=v1.29.8,sveltos-agent=present,type=services

Step 3: Deploy cloudnative-pg

Following ClusterProfile will deploy Cloudnative-pg in the managed cluster with label type=services

kubectl apply -f https://raw.githubusercontent.com/projectsveltos/sveltos/main/docs/assets/cloudnative-pg.yaml

Verify resources were deployed

sveltosctl show addons        
+--------------------------+---------------+-------------+------+---------+--------------------------------+----------------------------+
|         CLUSTER          | RESOURCE TYPE |  NAMESPACE  | NAME | VERSION |              TIME              |          PROFILES          |
+--------------------------+---------------+-------------+------+---------+--------------------------------+----------------------------+
| managed-services/cluster | helm chart    | cnpg-system | cnpg | 0.22.1  | 2024-10-25 15:47:54 +0200 CEST | ClusterProfile/deploy-cnpg |
+--------------------------+---------------+-------------+------+---------+--------------------------------+----------------------------+

Sveltos: Deploy Cloudnative-pg

Step 4: Instruct Sveltos to automatically deploy Postgres DB

Following configuration will instruct Sveltos to watch for managed cluster with labels postgres=required. Anytime such a cluster is detect, Sveltos will:

  1. Create a Postgres Cluster instance in the managed cluster with label type:services. DB will be exposed via a LoadBalancer service.
  2. Fetch credentials to access the DB.
  3. fetch the LoadBalancer service external ip: port
kubectl apply -f https://raw.githubusercontent.com/projectsveltos/sveltos/main/docs/assets/auto-deploy-postgres-cluster.yaml
kubectl apply -f https://raw.githubusercontent.com/projectsveltos/sveltos/main/docs/assets/fetch-postgres-data.yaml

Step 5: Onboard a new managed cluster

Whenever a new managed cluster is registered with Sveltos and labeled with 'postgres=required', Sveltos will initiate the deployment of a new Postgres database on the 'type=services' cluster. Once deployed, Sveltos will gather the essential connection information, including credentials, external IP address, and port number, for this newly created Postgres instance.

Here we created a new Civo cluster and registered with Sveltos:

kubectl create ns coke
sveltosctl register cluster --namespace=coke --cluster=my-app --kubeconfig=<managed cluster kubeconfig> --labels=postgres=required

Verify Sveltos deployed the Postgres Cluster and fetched the info necessary to connect:

kubectl get secret -n coke
NAME                         TYPE     DATA   AGE
pg-credentials          Opaque   2      0s

The Secret Data section contains:

data:
  password: bTloaW9UYUFBdVE1cFBQY1QzWGN6RDF2R3JUYzF5d3NVRTcwUTJQQXVUaTNucEZhRVdEYXpsZ1pmcnAzYWZwdg==
  user: dG9kbw==

kubectl get configmap -n coke                         
NAME                        DATA   AGE
...
pg-loadbalancer-data   2      58s

The ConfigMap Data section contains:

data:
  external-ip: 212.2.242.242
  port: "5432"

Step 6: Deploy an application that access the Postgres DB

Sveltos can now be used to deploy a Job in the coke cluster. This Job will access the Postgres DB in the services cluster.

This Job is expressed as a template and will be deployed by Sveltos in any cluster with label type=app.

kubectl apply -f https://raw.githubusercontent.com/projectsveltos/sveltos/main/docs/assets/job-to-create-table.yaml

kubectl label sveltoscluster -n coke my-app type=app

Step 7: Add another managed cluster

Here we created yet another Civo cluster and registered with Sveltos1. As result:

  1. Sveltos deployed a new Postgres DB in the services cluster;
  2. Fetched the credentials and external-ip:port info to access the cluster;
  3. Deployed a Job in the pepsi cluster that creates a table in the DB.

Multi-tenancy scenario

For multi-tenant clusters with a database per tenant, see this tutorial.

  1. kubectl create ns pepsi
sveltosctl register cluster --namespace=pepsi --cluster=cluster --kubeconfig=<managed cluster kubeconfig> --labels=postgres=required,type=app
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