Docker and docker-compose

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Goal

Containerize the Spring Boot app with a multistage Dockerfile and run it alongside PostgreSQL with docker-compose.

Prerequisites

• Profiles and configuration
• Docker installed

Multistage Dockerfile

# Stage 1: build with Maven
FROM maven:3.9-eclipse-temurin-21 AS builder
WORKDIR /app
COPY pom.xml .
RUN mvn dependency:go-offline
COPY src ./src
RUN mvn package -DskipTests

# Stage 2: runtime
FROM eclipse-temurin:21-jre-alpine
WORKDIR /app
COPY --from=builder /app/target/*.jar app.jar
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "app.jar"]

.dockerignore

target/
*.md
.env

docker-compose.yml

services:
  app:
    build: .
    ports:
      - "8080:8080"
    environment:
      - SPRING_PROFILES_ACTIVE=prod
      - DB_PASSWORD=compose-pass
      - JWT_SECRET=compose-secret
    depends_on:
      db:
        condition: service_healthy

  db:
    image: postgres:17-alpine
    environment:
      POSTGRES_DB: itemsdb
      POSTGRES_PASSWORD: compose-pass
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U postgres"]
      interval: 3s
      retries: 5
    volumes:
      - pgdata:/var/lib/postgresql/data

volumes:
  pgdata:

For the prod profile, ensure application-prod.properties uses the Docker service name db as the host:

spring.datasource.url=jdbc:postgresql://db:5432/itemsdb

Build and run

docker compose up --build

# In another terminal:
curl http://localhost:8080/items
# → []  (connected to Postgres in Docker)

Checkpoint

docker compose up --build -d
curl -s -o /dev/null -w "%{http_code}" http://localhost:8080/items
# 200
docker compose down -v

Next: Integration tests with Testcontainers — real Postgres in tests.