CLI reference

fern generate [--group <group>] [--version <version>]

fern generate runs the compiler. It will validate your API and run the generators specified in generators.yml.

If you don’t have a default-group specified in generators.yml, then you must specify a group using the --group option.

You can specify a version using the --version option. This version string is used when publishing SDKs to registries (e.g. npm).

Running locally

By default, the generation runs in the cloud. If you want to run it on your local machine, you can use the --local option. This will run each generator in a Docker container.

By default, Fern will delete the container after running. To keep the container around (e.g. to look at the generator’s logs), use the --keepDocker option.

fern check

fern check will validate that your API is valid.

fern upgrade

fern upgrade will upgrade your compiler version in fern.config.json to the latest version.

fern add <generator>

fern add adds a new generator to your generators.yml. You can view the full list of supported generators in the Generators section.

fern init

fern init adds a new API to your repo.

fern register

Advanced feature. You can register your API so it can be depended on by other APIs. Read more in the Depending on other APIs section.