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I am trying to figure out what is the best way to setup a spring boot application in such a way that its has its own jar dependencies but additional jars are added to classpath at runtime when its being run as java -jar command. What approach makes more sense

  1. Use the original jar (without dependencies added to it) and place all jars (application and runtime) in a folder on file system and use PropertiesLauncher to specify the loader.path to jars folder.

  2. Use the fat jar (with application jars) place the additional jars on the filesystem and somehow include those as additional jars that need to be added to classpath. Not sure how this can be done.

  3. Is there another better way to do this

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3 Answers 3

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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.

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3 Comments

That doesnt seems to be the case. If i specify loader.path it only seems to be picking up jars from there and ignoring the jars already packed in the fat jar. In this case it cant even find the spring boot files. If i place the spring boot jars in the jars folder then it works fine. $ java -Denv=dev -Dloader.path=jars:. -jar hdfsloader-0.0.1-SNAPSHOT.jar Exception in thread "main" java.lang.NoClassDefFoundError: org/springframework/boot/CommandLineRunner at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:634) at
okay this seems to work finally. I had to explicitly specify the jar file instead of current dir path (.) java -Denv=dev -Dloader.path=jars,hdfsloader-0.0.1-SNAPSHOT.jar -jar hdfsloader-0.0.1-SNAPSHOT.jar
OK, that looks degenerate, so thanks for the analysis. The current archive should be part of the classpath by default (here's a github issue).
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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.

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2 Comments

Putting loader.path=lib in application.properties file doesn't seem to work anymore in spring boot 2.0.0.RELEASE. I then tried putting loader.path=libin loader.properties file and place loader.properties file in the same location as application.properties file (e.g. /resources/config). It didn't work either. Finally, I placed the loader.propertiesfile in the same directory as my application.jar, and it worked. It appeared that the PropertiesLauncher did not read the "loader.properties" file inside the fat jar. Is it a bug in spring boot 2?
@Buck Not sure! I think I was using Spring 1.xx but I think they could be right as you can have different lib path on your (dev, stage or prod) env.
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thank you @Ashraf Sarhan, you rescue my two days :) I added in pom file:

         <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <layout>ZIP</layout>
                <executable>true</executable>
                <mainClass>vn.com.Mymainclass</mainClass>
                <excludes>
                    <exclude>
                        <groupId>com.vn.groupId</groupId>
                        <artifactId>excluded-id-a</artifactId>
                    </exclude>
                    <exclude>
                        <groupId>com.vn.groupId</groupId>
                        <artifactId>excluded-id-b</artifactId>
                    </exclude>
                </excludes>
            </configuration>
            <executions>
                <execution>
                    <goals>
                        <goal>repackage</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>

And Placed ./lib folder containing two jars of two files which excluded above beside with my-main-spring-boot-app.jar file, and I ran:

java -Dloader.path="lib/" -jar my-main-spring-boot-app.jar

It worked perfectly.

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