How to Deploy PostgreSQL on Kubernetes

Introduction

PostgreSQL is a reliable and robust relational database system featuring ACID-compliant transactions. It is designed to handle workloads of all sizes, making it a good fit for personal use and large-scale deployments such as data warehouses, big data servers, or web services.

Deploying PostgreSQL on Kubernetes creates a scalable and portable PostgreSQL instance, leveraging the good sides of both the RDBMS and the orchestration platform.

This article will show you two methods of deploying PostgreSQL on Kubernetes - using a Helm chart or manually creating your configuration.

Prerequisites

• A Kubernetes cluster with kubectl installed
• Helm 3 installed
• Administrative privileges on your system

Deploy PostgreSQL Using Helm

Helm gives you a quick and easy way to deploy a PostgreSQL instance on your cluster.

Step 1: Add Helm Repository

1. Search Artifact Hub for a PostgreSQL Helm chart that you want to use. Add the chart's repository to your local Helm installation by typing:

helm repo add [repository-name] [repository-address]

This article uses the Bitnami Helm chart for PostgreSQL installation.

2. After you have added the repository, update your local repositories.

helm repo update

The system confirms the successful update.

Step 2: Create and Apply Persistent Storage Volume

The data in your Postgres database need to persist across pod restarts.

1. To achieve this, create a PersistentVolume resource in a YAML file, using a text editor such as nano.

nano postgres-pv.yaml

The contents of the file define:

• The resource itself.
• The storage class.
• The amount of allocated storage.
• The access modes.
• The mount path on the host system.

This example uses the following configuration:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: postgresql-pv
  labels:
    type: local
spec:
  storageClassName: manual
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: "/mnt/data"

2. Save the file and exit. Then apply the configuration with kubectl:

kubectl apply -f postgres-pv.yaml

The system confirms the creation of the persistent volume.

Step 3: Create and Apply Persistent Volume Claim

1. Create a Persistent Volume Claim (PVC) to request the storage allocated in the previous step.

nano postgres-pvc.yaml

The example uses the following configuration:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: postgresql-pv-claim
spec:
  storageClassName: manual
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi

2. Save the file and exit. Apply the configuration with kubectl:

kubectl apply -f postgres-pvc.yaml

The system confirms successful PVC creation.

3. Use kubectl get to check if the PVC is connected to the PV successfully:

kubectl get pvc

The status column shows that the claim is Bound.

Step 4: Install Helm Chart

Install the helm chart with the helm install command. Add --set flags to the command to connect the installation to the PVC you created and enable volume permissions:

helm install [release-name] [repo-name] --set persistence.existingClaim=[pvc-name] --set volumePermissions.enabled=true

The system displays a report upon successful installation.

Step 5: Connect to PostgreSQL Client

1. Export the POSTGRES_PASSWORD environment variable to be able to log into the PostgreSQL instance:

export POSTGRES_PASSWORD=$(kubectl get secret --namespace default psql-test-postgresql -o jsonpath="{.data.postgresql-password}" | base64 --decode)

2. Open another terminal window and type the following port forwarding command to forward the Postgres port:

kubectl port-forward --namespace default svc/psql-test-postgresql 5432:5432

The system starts handling the port connection.

3. Minimize the port-forwarding window and return to the previous one. Type the command to connect to psql, a PostgreSQL client:

PGPASSWORD="$POSTGRES_PASSWORD" psql --host 127.0.0.1 -U postgres -d postgres -p 5432

sudo apt install postgresql-client-12

The psql command prompt appears, and the PostgreSQL is ready to receive your input.

Deploy PostgreSQL by Creating Configuration from Scratch

Manual configuration of Postgres on Kubernetes allows you to fine-tune your deployment configuration.

Step 1: Create and Apply ConfigMap

The ConfigMap resource contains the data that is used during the deployment process.

1. Create a ConfigMap YAML file in a text editor.

nano postgres-configmap.yaml

2. The most important part of the file is the data section, where you provide a name for the database, the username, and the password for logging into the PostgreSQL instance.

The example uses the following parameters in the ConfigMap file.

apiVersion: v1
kind: ConfigMap
metadata:
  name: postgres-config
  labels:
    app: postgres
data:
  POSTGRES_DB: postgresdb
  POSTGRES_USER: admin
  POSTGRES_PASSWORD: test123

3. Save the file and exit. Then apply the resource with kubectl:

kubectl apply -f postgres-configmap.yaml

The system confirms the successful creation of the configuration file.

Step 2: Create and Apply Persistent Storage Volume and Persistent Volume Claim

1. Create a YAML file for storage configuration.

nano postgres-storage.yaml

2. The Helm chart deployment method used two separate files for the Persistent Volume and the Persistent Volume Claim, but you can also place both configurations in one file, like in the example below.

kind: PersistentVolume
apiVersion: v1
metadata:
  name: postgres-pv-volume
  labels:
    type: local
    app: postgres
spec:
  storageClassName: manual
  capacity:
    storage: 5Gi
  accessModes:
    - ReadWriteMany
  hostPath:
    path: "/mnt/data"
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: postgres-pv-claim
  labels:
    app: postgres
spec:
  storageClassName: manual
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 5Gi

3. Save the file and exit. Apply the resources with kubectl:

kubectl apply -f postgres-storage.yaml

The system confirms the successful creation of both PV and PVC.

4. Check that the PVC is connected to the PV with the following command:

kubectl get pvc

The status of the PVC is Bound, and the PVC is ready to be used in the PostgreSQL deployment.

Step 3: Create and Apply PostgreSQL Deployment

1. Create a deployment YAML file.

nano postgres-deployment.yaml

2. The deployment file contains configuration of the PostgreSQL deployment and provides specifications for the containers and volumes:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: postgres
spec:
  replicas: 1
  selector:
    matchLabels:
      app: postgres
  template:
    metadata:
      labels:
        app: postgres
    spec:
      containers:
        - name: postgres
          image: postgres:10.1
          imagePullPolicy: "IfNotPresent"
          ports:
            - containerPort: 5432
          envFrom:
            - configMapRef:
                name: postgres-config
          volumeMounts:
            - mountPath: /var/lib/postgresql/data
              name: postgredb
      volumes:
        - name: postgredb
          persistentVolumeClaim:
            claimName: postgres-pv-claim

3. Save the file and exit. Apply the deployment with kubectl:

kubectl apply -f postgres-deployment.yaml

The system confirms the successful creation of the deployment.

Step 4: Create and Apply PostgreSQL Service

1. Lastly, create the YAML file to configure the PostgreSQL service.

nano postgres-service.yaml

2. Specify the service type and ports. The example uses the following configuration:

apiVersion: v1
kind: Service
metadata:
  name: postgres
  labels:
    app: postgres
spec:
  type: NodePort
  ports:
   - port: 5432
  selector:
   app: postgres

3. Save the file and exit. Apply the configuration with kubectl:

kubectl apply -f postgres-service.yaml

The system confirms the successful creation of the service.

4. Use the following command to list all resources on the system.

kubectl get all

The pod and the deployment show the 1/1 ready status. The desired number of replica sets reflect what is configured in the deployment YAML file.

Step 5: Connect to PostgreSQL

1. When all the resources are ready, use kubectl exec to log into the PostgreSQL instance.

kubectl exec -it [pod-name] --  psql -h localhost -U admin --password -p [port] postgresdb

2. The system asks for the password. Type in the password defined in Step 1 and press Enter. The psql command prompt appears.

The database is now ready to receive user input.

Conclusion

After completing this tutorial, you should know how to deploy PostgreSQL on Kubernetes using the manual method and a Helm chart.

For information about working with PostgreSQL databases, read How to Create a Database in PostgreSQL or browse one of the related articles below.