Make a Pod and Service for Postgres

In this lab you’ll make a pod for the Postgres container so your application can use storage. The completed pod and service from this lab will be a starting point for when you work on the next milestone.

Pod Definition

Start with a simple pod definition derived from the Kubernetes documentation. Copy and paste this YAML into a file named deployment/postgres-pod.yaml.

apiVersion: v1
kind: Pod
metadata:
  name: postgres
  labels:
    app: postgres
spec:
  containers:
  - name: postgres
    image: docker.io/postgres:14.1
    ports:
    - containerPort: 5432
    env:
    - name: POSTGRES_PASSWORD
      value: "django"
    - name: POSTGRES_DB
      value: "mysite"

Service Definition

Copy and paste the following into deployment/postgres-service.yaml:

apiVersion: v1
kind: Service
metadata:
  name: postgres
spec:
  type: ClusterIP
  selector:
    app: postgres
  ports:
    - protocol: TCP
      port: 5432
      targetPort: 5432

Deploy the Pod and Service

Deploy your pod with the command:

$ kubectl apply -f deployment/postgres-pod.yaml

Deploy your service with the command:

$ kubectl apply -f deployment/postgres-service.yaml

Verify the deployment and service:

$ kubectl get all

Access the Service

Access the service using the port-forward command:

$ kubectl port-forward service/postgres 5432:5432

On your dev box you should be able to initialize the empty database using Django:

$ export SECRET_KEY=blahblah
$ export DB_NAME=mysite
$ export DB_USER=postgres 
$ export DB_PASSWORD=django
$ export DB_HOST=localhost
$ python3 ./manage.py migrate 

Access the Pod

Create a shell in your Postgres pod and look around:

$ kubectl exec -it pod/postgres -- /bin/bash

Inside the container check for the database files.

root@postgres:/app# ls -l /var/lib/postgresql/data

Next week we’ll move this directory into permanent storage.