How to Pass External Jar File to Spring Boot Project

Add external library .jar to Spring boot .jar internal /lib

you can set 'includeSystemScope' to true.

<plugin>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-maven-plugin</artifactId>
  <configuration>
    <includeSystemScope>true</includeSystemScope>
  </configuration>
</plugin>

How to run a spring-boot jar with external jars which compile with maven dependency system?

For including a jar from a path into your Spring boot classpath see

External library folder for Spring Boot.

This means that you can safely manage your dependency in your pom by a repo (avoiding sytemPath dependencies).

Spring Boot Executable Jar with Classpath

If you just want add external libraries you can use the loader.path property.

java -Dloader.path="your-lib/" -jar your-app.jar

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UPDATE

If you also need to read additional files from the classpath you have to create/change the manifest file of your application.

Lets assume that your are initializing your Spring Boot context from the class de.app.Application. Your MANIFEST.MF should looks as follows:

Manifest-Version: 1.0
Main-Class: de.app.Application
Class-Path: your-lib/

And the you can simply start your app with java -Dloader.path="your-lib/" -jar MyApp.jar.

For more information about the MANIFEST.MF please see Working with Manifest Files: The Basics.

SpringBoot run-time dynamic external configuration with Jar files

I managed to answer my own question. I documented the approach I took at medium:
https://medium.com/@Jeef/dynamically-loading-libraries-into-a-springboot-application-at-run-time-80639ee5aab?sk=5851d25c7106307ff0f2b0a4171ab613

Also I built a sample project demonstrating the implementation on GitHub: https://github.com/jeeftor/SpringBoot-Dynamic-JarLoad

Spring Boot: Is it possible to use external application.properties files in arbitrary directories with a fat jar?

I managed to load an application.properties file in external path while using -jar option.

The key was PropertiesLauncher.

To use PropertiesLauncher, pom.xml file must be changed like this:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>  <!-- added -->
                <layout>ZIP</layout> <!-- to use PropertiesLaunchar -->
            </configuration>
        </plugin>
    </plugins>
</build>

For this, I referenced the following StackOverflow question: spring boot properties launcher unable to use . BTW, In Spring Boot Maven Plugin document(http://docs.spring.io/spring-boot/docs/1.1.7.RELEASE/maven-plugin/repackage-mojo.html), there is no mention that specifying ZIP triggers that PropertiesLauncher is used. (Perhaps in another document?)

After the jar file had been built, I could see that the PropertiesLauncher is used by inspecting Main-Class property in META-INF/MENIFEST.MF in the jar.

Now, I can run the jar as follows(in Windows):

java -Dloader.path=file:///C:/My/External/Dir,MyApp-0.0.1-SNAPSHOT.jar -jar MyApp-0.0.1-SNAPSHOT.jar

Note that the application jar file is included in loader.path.

Now an application.properties file in C:\My\External\Dir\config is loaded.

As a bonus, any file (for example, static html file) in that directory can also be accessed by the jar since it's in the loader path.

As for the non-jar (expanded) version mentioned in UPDATE 2, maybe there was a classpath order problem.

How can I @Autowire a spring bean that was created from an external jar?

You have to scan at least the package containing the class you want to inject. For example, with Spring 4 annotation:

@Configuration
@ComponentScan("com.package.where.my.class.is")
class Config {
...
}

It is the same principle for XML configuration.

How to add a dependency to a Spring Boot Jar in another project?

By default, Spring Boot repackages your JAR into an executable JAR, and it does that by putting all of your classes inside BOOT-INF/classes, and all of the dependent libraries inside BOOT-INF/lib. The consequence of creating this fat JAR is that you can no longer use it as a dependency for other projects.

From Custom repackage classifier:

By default, the repackage goal will replace the original artifact with the repackaged one. That's a sane behaviour for modules that represent an app but if your module is used as a dependency of another module, you need to provide a classifier for the repackaged one.

The reason for that is that application classes are packaged in BOOT-INF/classes so that the dependent module cannot load a repackaged jar's classes.

If you want to keep the original main artifact in order to use it as a dependency, you can add a classifier in the repackage goal configuration:

<plugin>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-maven-plugin</artifactId>
  <version>1.4.1.RELEASE</version>
  <executions>
    <execution>
      <goals>
        <goal>repackage</goal>
      </goals>
      <configuration>
        <classifier>exec</classifier>
      </configuration>
    </execution>
  </executions>
</plugin>

With this configuration, the Spring Boot Maven Plugin will create 2 JARs: the main one will be the same as a usual Maven project, while the second one will have the classifier appended and be the executable JAR.

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