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Service Definitions

This reference documents the Kubernetes Service resources that expose applications within the cluster.

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Frontend Service

The frontend service exposes the React/Nginx application on port 80.

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Configuration

apiVersion: v1
kind: Service
metadata:
  name: frontend-service
  namespace: govtech
  labels:
    app: frontend
    tier: presentation
    component: web
spec:
  type: ClusterIP
  selector:
    app: frontend
  ports:
  - name: http
    protocol: TCP
    port: 80
    targetPort: 80
  sessionAffinity: None
Source: platform/kubernetes/frontend/service.yaml:1-28

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Service Type

  • Type: ClusterIP
  • Access: Internal cluster only
  • External Access: Via Ingress/ALB

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Port Mapping

Service PortTarget PortProtocolDescription
8080TCPHTTP traffic to Nginx

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Backend Service

The backend service exposes the Node.js API application.

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Configuration

apiVersion: v1
kind: Service
metadata:
  name: backend-service
  namespace: govtech
  labels:
    app: backend
    tier: application
    component: api
spec:
  type: ClusterIP
  selector:
    app: backend
  ports:
  - name: http
    protocol: TCP
    port: 80
    targetPort: 3000
  sessionAffinity: None
Source: platform/kubernetes/backend/service.yaml:1-29

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Service Type

  • Type: ClusterIP
  • Access: Internal cluster only
  • External Access: Via Ingress/ALB

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Port Mapping

Service PortTarget PortProtocolDescription
803000TCPHTTP traffic to Node.js
The service listens on port 80 but forwards to the container’s port 3000 where the Node.js application runs.

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Database Services

PostgreSQL uses two services: a headless service for StatefulSet management and a standard ClusterIP service for application connections.

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Headless Service

Required for StatefulSet DNS resolution: 
apiVersion: v1
kind: Service
metadata:
  name: postgres
  namespace: govtech
  labels:
    app: postgres
    tier: database
spec:
  clusterIP: None
  publishNotReadyAddresses: true
  selector:
    app: postgres
  ports:
    - name: postgres
      port: 5432
      targetPort: postgres
      protocol: TCP
Source: platform/kubernetes/database/service.yaml:20-44

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ClusterIP Service

For backend application connections: 
apiVersion: v1
kind: Service
metadata:
  name: postgres-service
  namespace: govtech
  labels:
    app: postgres
    tier: database
  annotations:
    description: "Service para que el backend se conecte a PostgreSQL"
spec:
  type: ClusterIP
  selector:
    app: postgres
  ports:
    - name: postgres
      port: 5432
      targetPort: 5432
      protocol: TCP
Source: platform/kubernetes/database/service.yaml:49-70

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DNS Resolution

The headless service creates individual DNS records for each pod: 
postgres-0.postgres.govtech.svc.cluster.local
The ClusterIP service provides a stable connection point: 
postgres-service.govtech.svc.cluster.local:5432

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Port Mapping

Service PortTarget PortProtocolDescription
54325432TCPPostgreSQL connections

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Service Discovery

All services can be accessed using Kubernetes DNS:

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Within Same Namespace

frontend-service
backend-service
postgres-service

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Fully Qualified Domain Names

frontend-service.govtech.svc.cluster.local
backend-service.govtech.svc.cluster.local
postgres-service.govtech.svc.cluster.local

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Load Balancing

All services use round-robin load balancing (sessionAffinity: None) to distribute traffic evenly across available pods.

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Service Endpoints

Services automatically track healthy pod endpoints using:
  • Pod selector labels (e.g., app: backend)
  • Readiness probe status
  • Pod lifecycle state
Only ready pods receive traffic from the service.

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Connection Flow

Internet
  ↓
AWS ALB (Ingress)
  ↓
frontend-service:80 → frontend pods:80
  ↓
backend-service:80 → backend pods:3000
  ↓
postgres-service:5432 → postgres-0:5432

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Service Types

TypeUse CaseAccessibility
ClusterIPInternal servicesCluster only
HeadlessStatefulSet podsDNS per pod
LoadBalancerExternal accessPublic (via Ingress)

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