Hackforge Academy

Explanation

Docker networks allow containers to communicate with each other using container names instead of localhost. This is important when running Spring Boot, MySQL, Redis, and other services together.

Code:

docker network create app-network

docker run --network app-network student-api

Explanation

Docker volumes provide persistent storage outside the container's writable layer. They are commonly used for databases because database data should survive container restarts or removal.

Code:

docker volume create mysql-data

docker run -v mysql-data:/var/lib/mysql mysql:8

Explanation

Docker Compose allows multiple containers to be defined and managed using a single YAML file. It is useful for running a Spring Boot application together with MySQL, Redis, and other dependencies.

Code:

services:
  app:
    image: student-api:1.0
    ports:
      - "8080:8080"

  mysql:
    image: mysql:8
    environment:
      MYSQL_ROOT_PASSWORD: root

Explanation

Docker Compose creates a shared network between services. The Spring Boot application can connect to MySQL using the service name as the database hostname instead of localhost.

Code:

spring.datasource.url=jdbc:mysql://mysql:3306/studentdb
spring.datasource.username=root
spring.datasource.password=root

Explanation

Multi-stage builds separate the application build environment from the runtime environment. Maven and JDK tools can be used in the first stage, while the final image contains only the required JRE and application JAR, reducing image size.

Code:

FROM maven:3.9-eclipse-temurin-21 AS build
WORKDIR /app
COPY . .
RUN mvn clean package -DskipTests

FROM eclipse-temurin:21-jre
COPY --from=build /app/target/*.jar app.jar
ENTRYPOINT ["java", "-jar", "app.jar"]