docs: add development guidelines

DEVELOPING.md

@@ -0,0 +1,57 @@
+# Development guidelines
+
+Thanks a lot for contributing to Komga!
+
+## Commit messages
+
+Komga's commit messages follow the [Conventional Commits](https://www.conventionalcommits.org/) standard. This enables automatic versioning, releases, and release notes generation.
+
+Commit messages are enforced using commit hooks ran on the developer's PC. To install the necessary tooling, you need to run `npm install` in the root folder of the project. This will install the necessary commit hooks.
+
+## Project organization
+
+Komga is composed of 2 projects:
+- `komga`: a Spring Boot backend server that hosts the APIs, but also serves the static assets of the frontend.
+- `komga-webui`: a VueJS frontend, built at compile time and served by the backend at runtime.
+
+## Backend development
+
+### Spring profiles
+
+Komga uses Spring Profiles extensively:
+- `dev`: add more logging, disable periodic scanning
+- `prod`: log rotation, periodic scanning
+- `localdb`: a dev profile that stores the database in `./testdb`.
+- `docker`: set default path for the docker image
+- `flyway`: enable Flyway, the database migration tool. Included in `dev` and `prod`.
+- `noflyway`: disable Flyway. Only useful when adding new entities and you want Hibernate to update the database for you.
+- `generatesql`: used manually to write the SQL generated by Hibernate. Useful when adding new entities.
+
+### Gradle tasks
+
+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.
+- `copyWebDist`: build the frontend, and copy the bundle to `/resources/public`. You need to run this manually if you want to test the latest frontend build hosted by Spring.
+- `test`: run automated tests. Always run this before committing.
+
+`bootRun` needs to be run with a profile or list of profiles, usually:
+- `dev`: when testing with a blank database
+- `dev,localdb`: when testing with an existing database
+- `prod`: when testing prod-specific features
+
+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
+
+## Frontend development
+
+You can run a live development server with `npm run serve` from `/komga-webui`. The dev server will override the URL to connect to `localhost:8080`, so you can also run `gradle bootRun` to have a backend running, serving the API requests. The frontend will be loaded from `localhost:8081`.
+

README.md

@@ -27,6 +27,10 @@ Get the app from our [releases page](https://github.com/gotson/komga/releases) o
 
 Head over to our [website](https://komga.org) for more information.
 
+## Develop in Komga
+
+Check the [development guidelines](./DEVELOPING.md).
+
 ## Credits
 
 The Komga icon is based on an icon made by [Freepik](https://www.freepik.com/home) from www.flaticon.com