Docker Compose for Spring Boot application with PostgreSQL

Rafal BorowiecMarch 27th, 2020Last Updated: March 26th, 2020

1 900 2 minutes read

In this blog post you will learn how to configure Spring Boot application with PostgreSQL for running with Docker Compose.

This blog post covers:

Spring Boot application Dockerfile configuration with clean separation between dependencies and resources
Docker Compose configuration for running the application with PostgreSQL

Prerequisites

Docker
Java 13
Terminal
httpie (or curl)

Application

Generate the Maven based Spring Boot application with Spring Web, Spring Data JPA, Spring Data REST, PostgreSQL JDBC Driver dependencies.

The source code for this article can be found on Github: https://github.com/kolorobot/spring-boot-tc

`Dockerfile`

Create Dockerfile
Base Docker image uses Alpine Linux:

1	`FROM openjdk:13-alpine`

Do not run the application as root:

RUN addgroup -S spring && adduser -S spring -G spring
USER spring:spring

Do not deploy the fat-jar into the container, but rather split dependencies and application classes and resources into separate layers:

ARG DEPENDENCY=target/dependency
COPY ${DEPENDENCY}/BOOT-INF/lib /app/lib
COPY ${DEPENDENCY}/META-INF /app/META-INF
COPY ${DEPENDENCY}/BOOT-INF/classes /app

Note: ARG can be used to adjust the directory, in case you you have Gradle based project: docker build --build-arg DEPENDENCY=build/dependency -t spring-boot-tc .

Run the application inside the containers by pointing the main class and the libs in the java command:

ENTRYPOINT ["java","-cp","app:app/lib/*","pl.codeleak.samples.springboot.tc.SpringBootTestcontainersApplication"]

The complete Dockerfile:

FROM openjdk:13-alpine
RUN addgroup -S spring && adduser -S spring -G spring
USER spring:spring
ARG DEPENDENCY=target/dependency
COPY ${DEPENDENCY}/BOOT-INF/lib /app/lib
COPY ${DEPENDENCY}/META-INF /app/META-INF
COPY ${DEPENDENCY}/BOOT-INF/classes /app
ENTRYPOINT ["java","-cp","app:app/lib/*","pl.codeleak.samples.springboot.tc.SpringBootTestcontainersApplication"]

New to Docker? Docker explained in 12 minutes: https://www.youtube.com/watch?v=YFl2mCHdv24

Docker Compose

Create docker-compose.yml
We will have two services: db for PostgreSQL database and app for the application
- db service will use the postgres image from a public repository, it will expose port 5432 to the host and it will pass the environment properties POSTGRES_* to the container to setup the database name, user and password.
- app service will use the local build we created earlier, it will expose port 9000 to the host and it will pass the environment properties that will override the datasource configuration of the application (application.properties). The app service will depend on db service. The datasource URL uses the db as hostname which reflects the name of the db service.

The complete docker-compose.yml:

version: '3'
 
services:
  db:
    image: "postgres"
    ports:
      - "5432:5432"
    environment:
      POSTGRES_DB: tc
      POSTGRES_USER: tc
      POSTGRES_PASSWORD: tc
  app:
    build: .
    ports:
      - "9000:8080"
    environment:
      SPRING_DATASOURCE_URL: jdbc:postgresql://db/tc
      SPRING_DATASOURCE_USERNAME: tc
      SPRING_DATASOURCE_PASSWORD: tc
    depends_on:
      - db

New to Docker Compose? Docker Compose explained in 12 min: https://www.youtube.com/watch?v=Qw9zlE3t8Ko

Running the application

Package the application

$ ./mvnw clean package

To skip the tests use: -DskipTests=true

Extract libraries from fat-jar

$ mkdir -p target/dependency && (cd target/dependency; jar -xf ../*.jar)

Run with docker-compose

$ docker-compose build && docker-compose up

Verify the application is running and responding to requests

$ http get :9000/owners
 
HTTP/1.1 200
Connection: keep-alive
 
{
    "_embedded": {
        "owners": []
    },
    "_links": {
        "profile": {
            "href": "http://localhost:8080/profile/owners"
        },
        "self": {
            "href": "http://localhost:8080/owners{?page,size,sort}",
            "templated": true
        }
    },
    "page": {
        "number": 0,
        "size": 20,
        "totalElements": 0,
        "totalPages": 0
    }
}