Getting object scala in compiler mirror not found issue while running the application using jar

[AlokhPD11]

I have a multi-module application which has a java HTTP application (springboot, java 11) in one module and scala code in the second module.

The second module is included as a dependency in the first module as code in the second module needs to get invoked on REST invocations.

Here is a minimal project to reproduce the issue.

Steps to reproduce the issue

mvn clean compile
java -jar scala-compiler-issue-service/target/scala-compiler-issue-service-1.0-SNAPSHOT.jar

The above command to run the application fails on initialisation of the scala compiler.

Caused by: scala.reflect.internal.MissingRequirementError: object scala in compiler mirror not found.
        at scala.reflect.internal.MissingRequirementError$.signal(MissingRequirementError.scala:24) ~[scala-reflect-2.12.16.jar!/:na]
        at scala.reflect.internal.MissingRequirementError$.notFound(MissingRequirementError.scala:25) ~[scala-reflect-2.12.16.jar!/:na]
        at scala.reflect.internal.Mirrors$RootsBase.$anonfun$getModuleOrClass$5(Mirrors.scala:61) ~[scala-reflect-2.12.16.jar!/:na]
        at scala.reflect.internal.Mirrors$RootsBase.getPackage(Mirrors.scala:61) ~[scala-reflect-2.12.16.jar!/:na]

Interesting thing here is once we run the application using -cp command and pass the scala jars in classpath then the initialisation does not fail

java -cp scala-compiler-issue-service/target/scala-compiler-issue-service-1.0-SNAPSHOT.jar:scala-reflect-2.12.16.jar:scala-compiler-2.12.16.jar:scala-library-2.12.16.jar -Dloader.main=org.example.ServiceAPIApplication org.springframework.boot.loader.PropertiesLauncher

The 3 scala jars used are included in the project. They are fetched from maven repository using

wget https://repo1.maven.org/maven2/org/scala-lang/scala-reflect/2.12.16/scala-reflect-2.12.16.jar
wget https://repo1.maven.org/maven2/org/scala-lang/scala-library/2.12.16/scala-library-2.12.16.jar
wget https://repo1.maven.org/maven2/org/scala-lang/scala-compiler/2.12.16/scala-compiler-2.12.16.jar

[AlokhPD11]

Hi @davidB can you please take a look at this issue and help us with what further steps I could take to resolve this ?

[slandelle]

I don't think your issue has anything to do with this plugin.

This plugin only takes care of compiling the Scala code. Your issue happens at runtime, because some classes are missing from the classpath. Are you're expecting your jar to be a fatjar containing all the transitive dependencies of your module? If so, your issue is with this repackager (spring-boot?).

[AlokhPD11]

Thanks you for the response @slandelle, will check with the spring-boot community regarding this.