Database Deployment

Write a Deployment and Service for the database.

The database Deployment

The database takes its password from a Secret and keeps its data in a volume. In this project, for simplicity, we use a single-replica Deployment; in production, a StatefulSet, which provides persistent storage and a stable identity, is preferred for databases (in the advanced section):

apiVersion: apps/v1
kind: Deployment
metadata:
  name: db
  namespace: magaza
spec:
  replicas: 1
  selector:
    matchLabels: {app: db}
  template:
    metadata:
      labels: {app: db}
    spec:
      containers:
        - name: postgres
          image: postgres:16
          envFrom:
            - secretRef:
                name: db-gizli
          ports:
            - containerPort: 5432

The database service and secret

The API connects to the database by the name db; this needs a ClusterIP Service with the same name. The password is put in the Secret with a command and isn't added to the repository as YAML:

kubectl create secret generic db-gizli -n magaza \
  --from-literal=POSTGRES_PASSWORD="$DB_PAROLA" --from-literal=POSTGRES_DB=magaza

apiVersion: v1
kind: Service
metadata:
  name: db
  namespace: magaza
spec:
  selector:
    app: db
  ports:
    - port: 5432

Exercise The database service

Write a Service YAML: name db, namespace magaza; selector app: db; port 5432.

Show example solution

apiVersion: v1
kind: Service
metadata:
  name: db
  namespace: magaza
spec:
  selector:
    app: db
  ports:
    - port: 5432

Test yourself

Why is the database Deployment's replica count 1?
- It's cheaper
- A Service sees only one pod
- Several PostgreSQL copies can't write the same data; replication needs separate setup
- Kubernetes doesn't allow it
Show answer

Several PostgreSQL copies can't write the same data; replication needs separate setup — Database replicas are set up with their own replication protocols (e.g. an operator).

Make all keys of the Secret environment variables.

          envFrom:
            - ____:
                name: db-gizli

Show answer

          envFrom:
            - secretRef:
                name: db-gizli

Match.

db-gizli

Password Secret
Service db

DNS name db
replicas: 1

Single writer
StatefulSet

Production database

Next lesson: Web Deployment

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies