8. Application Setup

Hint

Abstract

This chapter describes how to inspect the registered applications and their instances and where the configuration of a flake lives.

8.1. Listing Applications

After an application is registered, it can be listed via:

flake-ctl list

The instances created from the registered applications can be listed per engine via:

flake-ctl podman show

flake-ctl firecracker show

Like all flake-ctl commands these operate on the setup of the calling user, see Getting Started.

8.2. The Flake Registry

Each application provides a configuration below /usr/share/flakes/ for system wide registration or ~/.config/flakes/ for user specific ones. The term flake is a short name for an application running inside an isolated environment. For the aws flake of Amazon’s SDK Utility as a Container App, the config file structure looks like the following:

~/.config/flakes/
├── aws.d
└── aws.yaml
NAME.yaml

The flake configuration. It describes the image, the target program, the engine options and, for VM applications, the kernel commandline of the instance.

NAME.d

A drop-in directory. The files placed here are read in alpha sort order and are attached to the master NAME.yaml file before it is parsed. A setting given again replaces the one from the file before, which allows to extend or overrule a registration without editing the file written by flake-ctl.

Both are plain text and are meant to be adjusted. A change becomes effective with the next call of the application, no re-registration is needed.

8.3. Removing an Application

A registration is deleted with the remove command of the engine it belongs to, e.g:

flake-ctl podman remove --app $HOME/bin/aws

flake-ctl firecracker remove --app $HOME/bin/fireshell

8.4. Reference Documentation

Please consult the manual pages for detailed information about the contents of the flake setup:

  • man 8 flake-ctl and the manual page of each subcommand

  • man 8 podman-pilot for container flakes

  • man 8 firecracker-pilot for VM flakes

  • man 8 flake-pilot for the registry layout and the user mode

The sources of the manual pages are also available online:

https://github.com/OSInside/flake-pilot/tree/main/doc