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Connecting Scaleway Managed Databases to Kubernetes Kapsule clusters

This guide explains how to set up and connect a Scaleway Managed Database for PostgreSQL or MySQL with a Scaleway Kubernetes Kapsule cluster.

We will walk you through the entire process using both the Scaleway CLI and Terraform approaches.

Before you start

To complete the actions presented below, you must have:

Method 1 - Using the Scaleway CLI

First, install the Scaleway CLI, and use scw init to set your API key and scw config set region par1 to set the default region (e.g. Paris).

Creating a Private Network

Create a Private Network that both your Kubernetes cluster and database will use:

scw vpc private-network create name=kube-db-network
Note

Note the Private Network ID from the output for later use.

Creating a Managed Database Instance

  1. Run the following command to create a Managed PostgreSQL (or MySQL) Database Instance:

    scw rdb instance create \
name=my-kube-database \
node-type=db-dev-s \
engine=PostgreSQL-15 \
is-ha-cluster=true \
user-name=admin \
password=StrongP@ssw0rd123 \
region=fr-par

    This creates a high-availability PostgreSQL 15 database with a public endpoint.

    Important

    At this point the database is exposed to the Internet.

  2. Add the Private Network endpoint to the database:

    scw rdb endpoint create \
<database-instance-id> \
private-network.private-network-id=<private-network-id> \
private-network.enable-ipam=true region-fr-par

  3. Get the Insance details and look for the public endpoint ID under the "Endpoints" section.

    scw rdb instance get <database-instance-id>

  4. Remove the public endpoint to ensure the database is only reachable from the Private Network and no longer exposed to the public Ineternet.

    scw rdb endpoint delete instance-id=<database-instance-id> <public-endpoint-id>

Creating a Kubernetes Kapsule cluster

  1. Run the following Scaleway CLI command to create a Kubernetes Kapsule cluster attached to the same Private Network:

    scw k8s cluster create \
name=my-kube-cluster \
type=kapsule \
version=1.28.2 \
cni=cilium \
pools.0.name=default \
pools.0.node-type=DEV1-M \
pools.0.size=2 \
pools.0.autoscaling=true \
pools.0.min-size=2 \
pools.0.max-size=5 \
private-network-id=<private-network-id>

  2. Wait for the cluster to be ready, then get the kubeconfig:

    scw k8s kubeconfig install <k8s-cluster-id> region=fr-par

Creating a Kubernetes secret for database credentials

Use kubectl to create a Kubernetes secret to store the database credentials:

kubectl create secret generic db-credentials \
--from-literal=DB_HOST=<private-network-db-hostname> \
--from-literal=DB_PORT=5432 \
--from-literal=DB_NAME=rdb \
--from-literal=DB_USER=admin \
--from-literal=DB_PASSWORD=StrongP@ssw0rd123

Deploying a sample application

  1. Create a Kubernetes deployment that will connect to the database. Save this as db-app.yaml:

    apiVersion: apps/v1
kind: Deployment
metadata:
name: postgres-client
spec:
replicas: 1
selector:
    matchLabels:
    app: postgres-client
template:
    metadata:
    labels:
        app: postgres-client
    spec:
    containers:
    - name: postgres-client
        image: postgres:latest
        command: ["sleep", "infinity"]
        env:
        - name: DB_HOST
        valueFrom:
            secretKeyRef:
            name: db-credentials
            key: DB_HOST
        - name: DB_PORT
        valueFrom:
            secretKeyRef:
            name: db-credentials
            key: DB_PORT
        - name: DB_NAME
        valueFrom:
            secretKeyRef:
            name: db-credentials
            key: DB_NAME
        - name: DB_USER
        valueFrom:
            secretKeyRef:
            name: db-credentials
            key: DB_USER
        - name: DB_PASSWORD
        valueFrom:
            secretKeyRef:
            name: db-credentials
            key: DB_PASSWORD

  2. Apply it to your cluster:

    kubectl apply -f db-app.yaml

  3. Check that your application can connect to the database:

    kubectl logs -f deployment/postgres-client

Method 2 - Using Terraform

For a more infrastructure-as-code approach, you can use Terraform or OpenTofu (open-source Terraform fork) to set up the same resources. Install Terraform and ensure the Scaleway Terraform provider is set up with terraform init -provider=scaleway/scaleway.

Setting-up Terraform files

  1. Create a new directory and set up your files:

    mkdir scaleway-kube-db
cd scaleway-kube-db

  2. Create a providers.tf file:

    terraform {
required_providers {
    scaleway = {
    source  = "scaleway/scaleway"
    version = "~> 2.40"
    }
}
}

provider "scaleway" {
access_key      = var.scaleway_access_key
secret_key      = var.scaleway_secret_key
project_id      = var.project_id
region          = var.region
zone            = var.zone
}

  3. Create a variables.tf file:

    variable "scaleway_access_key" {
description = "Scaleway Access Key"
type        = string
sensitive   = true
}

variable "scaleway_secret_key" {
description = "Scaleway Secret Key"
type        = string
sensitive   = true
}

variable "project_id" {
description = "Scaleway Project ID"
type        = string
}

variable "region" {
description = "Scaleway region (e.g., fr-par)"
type        = string
default     = "fr-par"
}

variable "zone" {
description = "Scaleway zone (e.g., fr-par-1)"
type        = string
default     = "fr-par-1"
}

variable "db_password" {
description = "Password for database user"
type        = string
sensitive   = true
}

variable "db_user" {
description = "Database username"
type        = string
default     = "admin"
}

  4. Create a main.tf file for the infrastructure:

    # Create Private Network
resource "scaleway_vpc_private_network" "private_net" {
name   = "kube-db-network"
region = var.region
}

# Create Managed PostgreSQL Database
resource "scaleway_rdb_instance" "database" {
name          = "my-kube-database"
node_type     = "db-dev-s"
engine        = "PostgreSQL-15"
is_ha_cluster = true
user_name     = var.db_user
password      = var.db_password

private_network {
    pn_id       = scaleway_vpc_private_network.private_net.id
    enable_ipam = true
}
}

# Kubernetes Cluster (Kapsule)
resource "scaleway_k8s_cluster" "kapsule" {
name                     = "my-kube-cluster-${random_id.suffix.hex}" # Make the name unique
version                  = "1.28.2"
cni                      = "cilium"
private_network_id       = scaleway_vpc_private_network.private_net.id
delete_additional_resources = true
}

# Kubernetes Node Pool
resource "scaleway_k8s_pool" "default_pool" {
cluster_id       = scaleway_k8s_cluster.kapsule.id
name            = "default-pool"
node_type       = "DEV1-M"
size            = 2
autoscaling     = true
min_size        = 2
max_size        = 5
autohealing     = true
container_runtime = "containerd"
}

# Generate a random suffix for uniqueness
resource "random_id" "suffix" {
byte_length = 4
}

# Output Database Connection Information
output "db_host" {
value = scaleway_rdb_instance.database.private_network[0].ip
}

output "db_port" {
value = scaleway_rdb_instance.database.db_host_port
}

output "kubeconfig" {
value     = scaleway_k8s_cluster.kapsule.kubeconfig
sensitive = true
}

Creating a terraform.tfvars file

Create a terraform.tfvars file to store your variables securely:

scaleway_access_key = "<your-scaleway-access-key>"
scaleway_secret_key = "<your-scaleway-secret-key>"
project_id          = "<your-scaleway-project-id>"
db_password         = "<your-strong-db-password>"

Applying the Terraform configuration

Initialize and apply the Terraform configuration:

terraform init
terraform apply

After confirming the plan, Terraform will create all the resources and output the database endpoint.

Connecting a real application

Now let's deploy a more realistic application that uses the database. Here's a simple Node.js application with Express and pg (PostgreSQL client):

Creating a Dockerfile for the application

The Dockerfile is used to create a Docker image for your application. Here's a simple example:

# Use the official Node.js 14 image.
# https://hub.docker.com/_/node
FROM node:14

# Create and change to the app directory.
WORKDIR /usr/src/app

# Copy application dependency manifests to the container image.
# A wildcard is used to ensure both package.json AND package-lock.json are copied.
# Copying this separately prevents re-running npm install on every code change.
COPY package*.json ./

# Install production dependencies.
RUN npm install --only=production

# Copy local code to the container image.
COPY . .

# Run the web service on container startup.
CMD [ "node", "app.js" ]

# Expose the port the app runs on
EXPOSE 8080

Creating the application files

You need to create the necessary files for your Node.js application. Here’s a simple app.js and a package.json file as an example:

app.js:

const express = require('express');
const { Pool } = require('pg');
const app = express();

// Get DB credentials from environment variables
const pool = new Pool({
user: process.env.DB_USER, // 'admin'
host: process.env.DB_HOST, // '<private-network-db-hostname>'
database: process.env.DB_NAME, // 'rdb'
password: process.env.DB_PASSWORD, 
port: process.env.DB_PORT, // '5432'
});

app.get('/', async (req, res) => {
try {
    const result = await pool.query('SELECT NOW() as now');
    res.send(result.rows);
} catch (err) {
    console.error(err);
    res.status(500).send(err.toString());
}
});

const PORT = process.env.PORT || 8080;
app.listen(PORT, () => {
console.log(`Server running on port ${PORT}`);
});

package.json:

{
"name": "node-postgres-app",
"version": "1.0.0",
"main": "app.js",
"dependencies": {
    "express": "^4.17.1",
    "pg": "^8.6.0"
}
}

Creating Kubernetes manifests for the application

  1. Ensure the previously created secret is cleared:
kubectl delete secret db-credentials

  1. Recreate the Secret Using kubectl create secret. Run the following command without any base64 encoding:

    kubectl create secret generic db-credentials \
--from-literal=DB_HOST=<private-network-db-hostname> \
--from-literal=DB_PORT=5432 \
--from-literal=DB_NAME=rdb \
--from-literal=DB_USER=admin \
--from-literal=DB_PASSWORD=StrongP@ssw0rd123

    Kubernetes will automatically handle the base64 encoding for you.

  2. Get the secret details:

    kubectl get secret db-credentials -o yaml

  3. Create two main Kubernetes manifests: one for the deployment and one for the service.

    deployment.yaml:

    apiVersion: apps/v1
kind: Deployment
metadata:
name: node-postgres-app
spec:
replicas: 1
selector:
    matchLabels:
    app: node-postgres-app
template:
    metadata:
    labels:
        app: node-postgres-app
    spec:
    containers:
        - name: node-postgres-app
        image: ${YOUR_DOCKER_REGISTRY}/node-postgres-app:latest
        ports:
            - containerPort: 8080
        env:
            - name: DB_HOST
            valueFrom:
                secretKeyRef:
                name: db-credentials
                key: DB_HOST
            - name: DB_PORT
            valueFrom:
                secretKeyRef:
                name: db-credentials
                key: DB_PORT
            - name: DB_NAME
            valueFrom:
                secretKeyRef:
                name: db-credentials
                key: DB_NAME
            - name: DB_USER
            valueFrom:
                secretKeyRef:
                name: db-credentials
                key: DB_USER
            - name: DB_PASSWORD
            valueFrom:
                secretKeyRef:
                name: db-credentials
                key: DB_PASSWORD
---
apiVersion: v1
kind: Secret
metadata:
name: db-credentials
type: Opaque
data:
DB_HOST: <base64-encoded-db-host>
DB_PORT: <base64-encoded-db-port>
DB_NAME: <base64-encoded-db-name>
DB_USER: <base64-encoded-db-user>
DB_PASSWORD: <base64-encoded-db-password>

    service.yaml:

    apiVersion: v1
kind: Service
metadata:
name: node-postgres-app
spec:
type: LoadBalancer
ports:
- port: 80
    targetPort: 8080
selector:
    app: node-postgres-app

Building and pushing the Docker image

Note

Replace ${YOUR_DOCKER_REGISTRY} with your Docker registry (e.g., Docker Hub username).

docker build -t ${YOUR_DOCKER_REGISTRY}/node-postgres-app:latest .
docker push ${YOUR_DOCKER_REGISTRY}/node-postgres-app:latest

Deploying the application to Kubernetes

  1. Apply the Kubernetes manifests:

    kubectl apply -f deployment.yaml
kubectl apply -f service.yaml

  2. Check the service to get the external IP:

    kubectl get service node-postgres-app

  3. Visit the application at the external IP to see it in action. If everything is set up correctly, you should see the current PostgreSQL time displayed when you access the application URL.

Security best practices

Use Private Networks

Always use Private Networks when connecting a Kubernetes cluster to a database. This ensures that database traffic never traverses the public internet, reducing the attack surface significantly.

Implement proper TLS

If you need to use a public endpoint, ensure you're using TLS with certificate verification:

For PostgreSQL, add this to your connection string:

sslmode=verify-full sslrootcert=/path/to/scaleway-ca.pem

Restrict database access with network policies

Implement Kubernetes Network Policies to control which pods can access the database:

Use secrets management

Consider using a secrets management solution like HashiCorp Vault or Kubernetes External Secrets to manage database credentials instead of storing them directly in Kubernetes Secrets.

Regularly rotate credentials

Implement a process to regularly rotate database credentials. This can be automated using tools like Vault or custom operators.

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