• This command can be used to transform a local Container using a given Container transformer.

Currently Available Official Transformers

  • pbxproj Can be used to patch one or more pbxproj (iOS project file) included in the Container, in specific ways.

  • build-config Can be used to update Build Configuration(s) -build settings- of a generated iOS Container.

  • script This transformer allows for executing an arbitrary script to transform the Container in some custom way. It supports transformation of both iOS and Android Containers.

  • git-patch Can be used to apply one or more sequential git patches to the Container.


ern transformer-container



  • The local file system path to the directory containing the Container to transform.

  • Default If this option is not provided, the command will look for a Container in the default platform directory ~/.ern/containergen/out/[platform].=


  • Specify the native platform of the target Container to transform.

  • This option is required, there is no default (unless --descriptor is used)


  • Specify the Container transformer to use (for ex build-config).

  • Can also include a specific version or a version range (for ex [email protected] or [email protected]^1.0.0)

  • If no version is specified, the latest available version of the publisher will be used at the time of publication (this is a bit risky given that new major publisher versions will contain breaking changes. We recommend that you use a specific version or version range allowing minor and patch updates only)

  • It is also possible to pass a local file system path to a Container transformer package (only used for transformers development).

  • This option is required, there is no default (unless --descriptor is used)


  • Extra configuration specific to the transformer (as json)

  • Some transformers might not need any extra configuration. Check the specific Container transformer documentation for reference.

  • There is three different ways to provide the json extra configuration :

    • As a json string

      For example --extra '{"configKey": "configValue"}'

    • As a file path

      For example --extra <path>/transformer-config.json

      In that case, the configuration will be read from the file

    • As a Cauldron file path

      For example --extra cauldron://config/publishers/transformer-config.json

      In that case, the configuration will be read from the file stored in Cauldron.

      For this way to work, the file must exist in Cauldron (you can add a file to the cauldron by using the ern cauldron add file command).

ern create-container | Create a new Container (native or JavaScript only) locally to the workstation. ern publish-container | Publish a Container.