Containers have been making revolutionary changes in software world. Previous systems were mostly powered by virtual machines. Today many software pioneers like Google, Amazon, Redhat and Docker Inc. convert the industry in that way. Docker was released in 2013 by Solomon Hykes. Now it is developing by Docker Inc. It is relying on LXC(Linux Containers) which was invented in 2008 by IBM.

Introduction

In this post, take a look to spring boot project which use docker and docker-compose to work with its postgres database. See how docker is configured with a spring boot project.

This post will not explain docker and its concepts in deep. But to be on the same page let’s take a look some docker concepts like Dockerfile, image and container. Dockerfile have all instruction sets of the single image. It may extend or contain different images. When build a Dockerfile, it produces an image. When run a Dockerfile, it produces a container. In that perspective they are look like source code(Dockerfile), compiled code(image) and process(container).

Configuration

There are 2 Dockerfile and 1 docker-compose yaml files inside the project.

Configure spring boot service

Below Dockerfile is using define java process which is spring boot service jar. It has 3 instructions. First get the java:8 image, then copy created project jar as service.jar and set the ENTRYPOINT as how this process should be run.


# Alpine Linux with OpenJDK JRE
FROM java:8
COPY build/libs/spring-boot-containers-0.1.0.jar ./service.jar
ENTRYPOINT exec java $JAVA_OPTS -jar /service.jar

Configure postgres

Second Dockerfile is under project root > docker > postgres folder. It gets the latest postgres image. Then copy init-user-db.sh file to /docker-entrypoint-initdb.d/init-user-db.sh. That path is in postgres container.

FROM postgres:latest
COPY init-user-db.sh /docker-entrypoint-initdb.d/init-user-db.sh

When postgres container start to run, it will use that file as a database initialization. Currently below shell is just connect the postgres server inside the postgres container and run GRANT comment for POSTGRES_USER.

#!/bin/bash
set -e

psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" -d "$POSTGRES_DB" <<-EOSQL
    GRANT ALL PRIVILEGES ON DATABASE "$POSTGRES_DB" TO "$POSTGRES_USER";
    create table if not exists product
    (
      id  bigint not null constraint product_pkey primary key,
      name  varchar(255) UNIQUE
    );
    CREATE SEQUENCE IF NOT EXISTS hibernate_sequence START 1;
EOSQL

For more information about initialization script check postgres docker official documentation.

Configure docker-compose

POSTGRES_USER and POSTGRES_DB are defined at docker-compose.yaml under project root > docker folder. Let’s take a look to docker-compose.yaml. There are two services defined. postgres service will use the Dockerfile inside the postgres folder so build attribute have postgres folder name. environment is using to give different naming to default database, user and password which created in initialization time. Please check above init-user-db.sh file again to see how these parameters are used. That’s reason why didn’t create any database name as store in init-user-db.sh file, because in below file with POSTGRES_DB environment variable rename the default database name to store.

For more information check postgres environment variable documentation.


version: "3.7"
services:
  postgres:
    build: postgres
    environment:
      POSTGRES_USER: dbuser
      POSTGRES_PASSWORD: password
      POSTGRES_DB: store
    ports:
    - 5432:5432
  spring-boot-containers:
    build: ../
    ports:
      - "12345:12345"
    links:
      - postgres
    environment:
      SPRING_PROFILES_ACTIVE: dev
      JAVA_HEAP_SIZE_MB: 1024

Second service definition named as spring-boot-containers. It has Dockerfile definition in parent folder so build attribute set it as ../. It linked postgres service which means it needs that service. Also environment variable SPRING_PROFILES_ACTIVE is set to dev, which will initialize spring boot dev profile when service is started. Service will expose its port on 12345.

How to run the project

As last step run the service via below commands. These commands are combined in cleanRun.sh so it is easy to run the project just with ./cleanRun.sh

./gradlew clean build -x test
cd docker || exit
docker-compose down -v
docker-compose up --build
cd .. || exit

Now application is started to run on http://localhost:12345. Send POST request with below body to http://localhost:12345/v1/product to create a product.

    {"name":"product001"}

Then query product to send GET request to http://localhost:12345/v1/product/product001.

Notes

This project should be used in development environment. But it may be used as a base of some project and can be prepare for production usage as well.

Result

You can find the all project on Github

References

https://spring.io/guides/gs/spring-boot-docker/

Happy coding :)


muzir

A software developer who loves open source and try to contribute few of them.