Getting Started with Modular

Prerequisities

  1. Follow instructions under Development in Fuchsia Documentation to get the source, setup, build and run Fuchsia.
  2. Follow instructions in the Ledger User Guide to setup the Ledger and its dependencies. In particular, make sure to do the “minfs setup” as linked under the Prerequisites.

To be able to run modules from the Fuchsia command line, you need to select a Fuchsia build configuration that does not start device_runner and shows a graphical user shell right at boot time. You can use for example the test_modular configuration in fx set and build as follows:

fx set x64 --packages peridot/packages/products/test_modular
fx full-build

If fx is not in your PATH, you should add .jiri_root/bin to your PATH.

Running

An application can be run as a module in a story using dev_user_shell. For example (from test runner invocation):

device_runner --test --account_provider=dev_token_manager \
  --device_shell=dev_device_shell --user_shell=dev_user_shell \
  --story_shell=dev_story_shell \
  --user_shell_args=--root_module=parent_child_test_parent_module

dev_device_shell is used to log in a dummy user directly without going through an authentication dialog. dev_user_shell runs the module given to it in --user_shell_args in a story.

The flags --user_shell and --user_shell_args are read by device_runner. The value of --user_shell is the application that is run as the user shell. The value of --user_shell_args is a comma separated list of arguments passed to the user shell application. In this example, these arguments are in turn more flags. Commas inside the value of such arguments are escaped by backslashes. The value of --root_module selects the module to run. The value of --root_link is a JSON representation of the initial data the module is started with.

The user name provided by dev_device_shell can be set with --user. It is used by device_runner when opening the Ledger. However, the --user parameter does not work for userpicker_device_shell, because that shell displays a GUI to select the user to login.

Module URLs

Applications are generally referenced by URLs. If the application binary is in a location where application manager expects it, e.g. /pkgfs/packages, the URL can be relative. Otherwise, the URL should be relative with an absolute path, or absolute altogether.