Spring Boot Packaging

Spring Boot provides several packaging options for building and packaging your Spring Boot applications. The choice of packaging depends on how you want to distribute and deploy your application. Here are some common packaging options:

1. JAR (Java Archive) Packaging:

• The JAR packaging is the default packaging for Spring Boot applications.
• It packages your application as a standalone, executable JAR file.
• You can run the application using the java -jar command, and it embeds an embedded web server (e.g., Tomcat, Jetty, or Undertow), making it self-contained. To build a JAR package, use the following Maven command:

   mvn clean package

To run the JAR package:

   java -jar your-application.jar

2. WAR (Web Application Archive) Packaging:

• You can package your Spring Boot application as a traditional WAR file.
• This is useful if you want to deploy your application to an external servlet container like Apache Tomcat or Jetty. To build a WAR package, you need to make changes to your project configuration to extend SpringBootServletInitializer and configure the packaging type as WAR. In Maven, you need to set <packaging>war</packaging> in your pom.xml. After making the necessary changes, build the WAR package with:

   mvn clean package

Then, you can deploy the WAR file to your servlet container.

3. Executable JAR with Dependencies (Uber JAR):

• Spring Boot allows you to create an executable JAR that includes all its dependencies (also known as an Uber JAR or Fat JAR).
• This packaging option produces a single JAR file that contains your application code and all its dependencies, making it easy to distribute and run on a target system without worrying about classpath issues. You can build an executable JAR with dependencies using a Maven plugin like spring-boot-maven-plugin. It’s configured in your pom.xml and can be executed with:

   mvn clean package spring-boot:repackage

The resulting JAR will be located in the target directory and can be run with java -jar.

4. Docker Packaging:

• Spring Boot applications can be packaged into Docker containers for easy deployment and scaling in container orchestration platforms like Kubernetes.
• You create a Docker image with your application and its dependencies. To create a Docker image, you need to create a Dockerfile for your application. Then, you can use Docker commands or container orchestration tools like Docker Compose or Kubernetes to build and deploy your Docker image.

4. Executable Script Packaging:

• Spring Boot also supports packaging applications as executable scripts for Unix-like systems.
• You can create a shell script or a Windows batch script that contains the necessary commands to run your application. To create an executable script, you typically package it along with your JAR file. Users can then execute the script to start the application.

The choice of packaging depends on your deployment requirements and the infrastructure you’re targeting. For standalone applications, JAR packaging is often the preferred option because it’s self-contained and easy to manage. For more complex deployments in enterprise environments, you might opt for WAR packaging or Docker containers, depending on your organization’s infrastructure and practices.