Plugins and Packages repository structure

This provides an overview of the structure of the flutter/plugins and flutter/packages repository.

flutter/plugins

Plugins

flutter/plugins uses the federated plugin model. If you are not familiar with federated plugins, start with reading the federated plugin overview to understand the terms below.

All plugins are located in the packages/ directory. In theory, each plugin should have the following layout:

• some_plugin/ - A directory containing the individual packages of the federated plugin:
  • some_plugin/ - The app-facing package
  • some_plugin_platform_interface/ - The platform interface
  • some_plugin_android/, some_plugin_ios/, some_plugin_web/, some_plugin_windows/, some_plugin_macos/, and/or some_plugin_linux/ - The individual platform implementations, as applicable

This layout reflects the goal of having all plugins in flutter/plugins being fully federated. (While this is not strictly necessary, as all packages are being maintained by the Flutter team, using a fully federated structure ensures that we are testing the federated model and finding issues and areas for improvement specific to federation.)

In practice (as of May 2021) most plugins are not yet fully federated, and some are not federated at all, since the process of converting them from their pre-federated forms is ongoing. The two most common alternate structures are:

Semi-federated

• some_plugin/
  • some_plugin/ - The app-facing package, also containing ios/ and android/ folders containing their implementations
  • some_plugin_platform_interface/ - The platform interface
  • some_plugin_web/, some_plugin_windows/, some_plugin_macos/, and/or some_plugin_linux/ - Federated implementations

These are packages that have mobile implementations that predate the federated model, but have had a platform implementation extracted to add new platforms via federation. Eventually the ios/ and android/ implementations will be extracted to their own packages.

Unfederated

• some_plugin/ - An unfederated plugin containing mobile implementations

These are packages that predate the federated model and have not had web or desktop implementations added. They should be federated at some point as well, unless extending them to other platforms would never make sense.

Tools

script/tool/ contains the tooling used to manage tasks across all plugins in the repository. See its README for more information.

flutter/packages

Most packages are located in packages. A few which are derived heavily from third-party code are instead in third_party/packages/.