Flamingock in kotlin project

[elvislicsari]

Hi,

I'm having some issues enabling flamingock in a kotlin spring boot project with maven as a dependency management.
Is the library supposed to work for this kind of project ?

I can offer more details on how i configured it, if the answer is yes.

Also, didn't had any issues with a java spring boot maven project.

Thanks,
Elvis

[dieppa]

Hi @elvislicsari ,

We haven’t tested the Kotlin + Maven combination specifically yet.

That said, we use Flamingock Community internally in our cloud services to manage the evolution of external systems, and it works smoothly, so in principle it should work.

Could you please share your configuration and the error details? We’ll try to reproduce it and investigate from there.

Regards

[elvislicsari]

Hi Antonio,

Thanks a lot for the help.

I'm using flamingock 1.2.0 dependencies in a kotlin spring boot project:

<dependency>
    <groupId>io.flamingock</groupId>
    <artifactId>flamingock-mongodb-springdata-targetsystem</artifactId>
</dependency>
<dependency>
    <groupId>io.flamingock</groupId>
    <artifactId>flamingock-mongodb-sync-auditstore</artifactId>
</dependency>
<dependency>
    <groupId>io.flamingock</groupId>
    <artifactId>flamingock-springboot-integration</artifactId>
</dependency>
...
<plugin>
    <groupId>org.jetbrains.kotlin</groupId>
    <artifactId>kotlin-maven-plugin</artifactId>
    <version>${kotlin.version}</version>
    <executions>
        <execution>
            <id>kapt</id>
            <goals>
                <goal>kapt</goal>
            </goals>
            <configuration>
                <annotationProcessorPaths>
                    <annotationProcessorPath>
                        <groupId>io.flamingock</groupId>
                        <artifactId>flamingock-processor</artifactId>
                        <version>${flamingock-bom.version}</version>
                    </annotationProcessorPath>
                </annotationProcessorPaths>
            </configuration>
        </execution>

        <execution>
            <id>compile</id>
            <goals>
                <goal>compile</goal>
            </goals>
        </execution>

        <execution>
            <id>test-compile</id>
            <goals>
                <goal>test-compile</goal>
            </goals>
        </execution>
    </executions>

</plugin>

The flamingock processor is taken into account during the mvn clean install. Can see in the logs something like:

[INFO] Note: 	 [Flamingock] Auto-detected project root: MY_ROOT_DIR
[WARNING] warning: Supported source version 'RELEASE_8' from annotation processor 'org.jetbrains.kotlin.kapt.base.ProcessorWrapper' less than -source '21'
[INFO] Note: 	 [Flamingock] Processing pipeline configuration
[INFO] Note: 	 [Flamingock] Searching for @EnableFlamingock annotation
[INFO] Note: 	 [Flamingock] Searching for code-based changes
[INFO] Note: 	 [Flamingock] Using io.flamingock.core.processor.FlamingockAnnotationProcessorPlugin for discover changes
[INFO] Note: 	 [Flamingock] Searching for code-based changes (Java classes annotated with @Change annotation)
[INFO] Note: 	 [Flamingock] Searching for @FlamingockCliBuilder annotation
[INFO] Note: 	 [Flamingock] Reading flamingock pipeline from @EnableFlamingock annotation stages configuration
[INFO] Note: 	 [Flamingock] Generated metadata: 2 stages, 2 changes

I'm putting the @EnableFlamingock annotation on the App kotlin class (annotated with @SpringBootApplication). Also tried with putting the @EnableFlamingock annotation on a @Configuration kotlin class which is definitelly picked up by spring boot.

@EnableFlamingock(
    stages = [
        Stage(name = "main", location = "my.package"),
        Stage(name = "main2", location = "my.package2")
    ]
)

Can confirm that the my.package is correct and the @Change are located correctly. An example of a change in these packages

@TargetSystem(id = "my_db")
@Change(id = "_0002__DropMongockCollections", author = "author", transactional = false)
class _0002__DropMongockCollections {

    @Apply
    fun apply(mongoTemplate: MongoTemplate) {
        mongoTemplate.dropCollection("mongockLock")
        mongoTemplate.dropCollection("mongockChangeLog")
    }
}

The metadata.json file is located in META-INF/flamingock/metadata.json and contains:

{
  "pipeline": {
    "stages": []
  },
  "builderProvider": {
    "className": "io.flamingock.springboot.FlamingockAutoConfiguration",
    "methodName": "flamingockBuilder",
    "acceptsArgs": true
  },
  "configFile": "",
  "properties": {}
}

The issue is that at runtime, flamingock is running, but the stages and changes are not picked-up. These are the logs:

2026-04-28 15:29:35,817 [main] INFO   FK-Builder          : Generated runner id:  833de5b1-23b9-43b3-a2a6-7f883e051f75@LWJD9DGY3#6555ec19-6c8e-4721-b2a1-8264a3d4f4cf
2026-04-28 15:29:36,414 [main] INFO   FK-PipelineRunner   : Flamingock execution started [stages=0 changes=0]
2026-04-28 15:29:36,517 [main] INFO   FK-PipelineRunner   : Flamingock execution completed [duration=81ms applied=0 skipped=0]

I'm also using intellij, not sure if that really matters.

Thanks again,
Elvis

[osantana85]

Hi @elvislicsari ,

Thanks again for the detailed information.

We have been able to validate the Spring Boot + Maven + Kotlin combination successfully on our side, so at this point it does not look like a general incompatibility with that stack. The problem seems more likely to be related to compilation or packaging in the specific project setup.

There is one important detail in your report that looks inconsistent to us.

You mentioned that you are using Flamingock 1.2.0, but the metadata.json you shared does not seem to match the format we would expect from that version. In particular, the file you posted contains:

"configFile": ""

whereas in Flamingock 1.2.0 the generated metadata should use:

"pipelineFile": ""

That makes us suspect that the metadata.json being used at runtime may not be the one generated by the 1.2.0 annotation processor, or that there may be a version mismatch somewhere in the build or runtime classpath.

In other words, the issue may not be the Spring Boot + Maven + Kotlin combination itself, but rather that a different or older metadata format is ending up in the final artefact, or that the correct metadata is being replaced during the build/package process.

This would also fit with the behaviour you described: the processor detects stages and changes during compilation, but at runtime Flamingock starts with stages=0 changes=0.

Could you please double-check whether there is any dependency version mismatch in your project, or whether the metadata.json included in the final packaged artefact differs from the one generated during compilation?

Regards

[elvislicsari]

Thanks a lot for the help and for pointing it out.
Root cause was a manually added flamingock/metadata.json file in the application that was ending up overwriting that one that's generated.