spring boot loading jars (application dependencies and external file system jars)

The PropertiesLauncher was designed to work with fat jars, so you should be able to keep the fat jar and add as many additional dependencies as you like in an external location, e.g. with loader.path=/opt/app/lib:lib. I guess that's your option 2? If it doesn't work we can discuss in a github issue.

I resolved this issue using the following spring-boot-maven-plugin configuration, I had to build my Uber jar without excluded artifacts to create my external "lib" directory, then I added my excluded artifacts again and packaged my Uber jar with my application specific dependencies only.

           <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>1.3.1.RELEASE</version>
                <configuration>
                    <layout>ZIP</layout>
                    <executable>true</executable>
                    <excludeArtifactIds>
                        <!-- My libs which will be packaged with my Uber jar-->
                        <!-- core,data-feeder,engine,lightspeed-tcp-api,order-manager,store,strategies,utils,viewer -->
                        <!-- Other libs -->
                        antlr,aopalliance,aspectjrt,aspectjweaver,classmate,commons-lang,
                        dom4j,h2,hibernate-commons-annotations,hibernate-core,hibernate-entitymanager,
                        hibernate-jpa-2.1-api,hibernate-validator,jackson-annotations,jackson-core,jackson-databind,
                        jandex,javassist,javax.transaction-api,jboss-logging,jboss-logging-annotations,jcl-over-slf4j,
                        jul-to-slf4j,log4j-over-slf4j,logback-classic,logback-core,mysql-connector-java,slf4j-api,
                        snakeyaml,spring-aop,spring-aspects,spring-beans,spring-boot,spring-boot-autoconfigure,
                        spring-boot-starter,spring-boot-starter-aop,spring-boot-starter-data-jpa,spring-boot-starter-jdbc,
                        spring-boot-starter-logging,spring-boot-starter-tomcat,spring-boot-starter-web,
                        spring-boot-starter-websocket,spring-context,spring-core,spring-data-commons,spring-data-jpa,
                        spring-expression,spring-jdbc,spring-messaging,spring-orm,spring-tx,spring-web,spring-webmvc,
                        spring-websocket,tomcat-embed-core,tomcat-embed-el,tomcat-embed-logging-juli,tomcat-embed-websocket,
                        tomcat-jdbc,tomcat-juli,validation-api,xml-apis
                    </excludeArtifactIds>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

Then, I added the following property to my "application.properties" which inside my jar "resources/" dir to specify my "lib" dir for Spring PropertiesLauncher where I put "lib" dir along with my jar in the same dir.

loader.path=lib/

Finally, I did run my jar using the following command

java -jar back-tester-0.0.1-beta-01.jar

Also, you can add the "loader.path" property to your command line without putting it in your "application.properties" like the following command but this way didn't work with me as I packaged my jar as an executable one which I'm running as linux service.

java -Dloader.path="lib/" -jar back-tester-0.0.1-beta-01.jar

Now, I successfully reduced my jar size from 29 M to only 1 M jar which contains only my application specific libs and it works out of the box.