• Java JDK version 21+

Komga uses Spring Profiles extensively:

• dev: add more logging, disable periodic scanning, in-memory database, and enable CORS from localhost:8081 (the frontend dev server)
• localdb: a dev profile that stores the database in ./localdb.
• noclaim: will create initial users at startup if none exist and output users and passwords in the standard output
  • if dev is active, will create admin@example.org with password admin, and user@example.org with password user
  • if dev is not active, will create admin@example.org with a random password that will be shown in the logs

The backend project uses gradle to run all the necessary tasks. If your IDE does not have gradle integration, you can run the tasks from the root directory using ./gradlew <taskName>.

Here is a list of useful tasks:

• bootRun: run the application locally, useful for testing your changes.
• test: run automated tests. Always run this before committing.
• jooq-codegen-primary: generates the jOOQ DSL.

bootRun needs to be run with a profile or list of profiles, usually:

• dev,noclaim: when testing with a blank database
• dev,localdb,noclaim: when testing with an existing database

There are few ways you can run the task with a profile:

• ./gradlew bootRun --args='--spring.profiles.active=dev'
• On Linux: SPRING_PROFILES_ACTIVE=dev ./gradlew bootRun
• On Windows:

SET SPRING_PROFILES_ACTIVE=dev
./gradlew bootRun

• If you use IntelliJ, some Run Configurations are saved in the repository and available from the Gradle panel

To build the Docker image, you need to:

• have the webui built and copied to /resources/public
• prepare the docker image via JReleaser. To do so, run ./gradlew jreleaserPackage.
• the Dockerfile will be available in komga/build/jreleaser/package/docker/