Introduction to Multi-stage Dockerfile with SpringBoot and PostgreSQL Example

Updated August 2026 — full tutorial restored for this URL.

A multi-stage Dockerfile builds your Spring Boot JAR in a JDK image, then copies only the JAR into a slim JRE image. Here we pair it with PostgreSQL.

Companion: Spring Boot + MySQL with Docker.

1. Why multi-stage
2. Multi-stage Dockerfile
3. Spring datasource for Postgres
4. Compose with PostgreSQL
5. Tips

1. Why multi-stage

• Final image has no Maven/Gradle caches or source
• Smaller attack surface and faster pulls
• Same Dockerfile works in CI

2. Multi-stage Dockerfile

FROM eclipse-temurin:21-jdk AS build
WORKDIR /workspace
COPY mvnw pom.xml ./
COPY .mvn .mvn
RUN ./mvnw -q -DskipTests dependency:go-offline
COPY src src
RUN ./mvnw -q -DskipTests package

FROM eclipse-temurin:21-jre AS runtime
WORKDIR /app
RUN useradd -r spring
USER spring
COPY --from=build /workspace/target/*.jar app.jar
EXPOSE 8080
ENTRYPOINT ["java","-XX:+UseContainerSupport","-jar","/app/app.jar"]

3. Spring datasource for Postgres

spring.datasource.url=jdbc:postgresql://postgres:5432/appdb
spring.datasource.username=app
spring.datasource.password=secret
spring.jpa.hibernate.ddl-auto=update
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect

4. Compose with PostgreSQL

services:
  postgres:
    image: postgres:16
    environment:
      POSTGRES_DB: appdb
      POSTGRES_USER: app
      POSTGRES_PASSWORD: secret
    ports: ["5432:5432"]
    volumes: ["pgdata:/var/lib/postgresql/data"]
  api:
    build: .
    ports: ["8080:8080"]
    depends_on: [postgres]
volumes:
  pgdata:

5. Tips

• Layer dependency download before copying src for faster rebuilds.
• Pass secrets via env / Compose secrets, not baked into the image.
• Add a healthcheck on Postgres before starting Flyway-heavy apps.