Automatically update OpenAPI specs on PR

[silvanheller]

Currently, code review for PRs has to manually check whether there is a need for the OpenAPI specs to be updated, and then that has to be done manually.

One good way to avoid this Problem would be to have a Github Action that automatically re-generates the OpenAPI specs on each PR and then pushes the changes to the PR branch. This can be done using https://github.com/ad-m/github-push-action.

[sauterl]

This is a very good idea!

Currently, the way to generate the OAS, one starts locally a Cineast instance and downloads the OAS from there.

There is (or was at one point) a CLI command to generate the OAS, which might be handier in this particular case.

[silvanheller]

I think you just run ./gradlew generateOpenApiSpecs (at least this is what is documented in the README)

[sauterl]

@silvanheller Indeed, ots nothong more than ./graldew generateOpenApi.