The app keys and values in snapcraft.yaml detail the applications and services that a snap wants to expose, including how they’re executed and which resources they can access.
See Snapcraft top-level metadata and Snapcraft parts metadata for details on how apps and parts are configured within snapcraft.yaml.
apps
Type: dict
A map of app-names representing entry points to run for the snap.
apps.<app-name>
Type: dict
The name exposed to run a program inside the snap.
If <app-name> is the same as name, the program will be invoked as app-name. However, if they differ, the program will be exposed as <snap-name>.<app-name>.
Keys for apps
The following are keys that can be within apps. (for example, apps.<app-name>.daemon):
adapter
Type: enum
Can be one of the following:
none(Disables the creation of an env variable wrapper.)full(default)
Snapcraft normally creates a wrapper holding common environment variables. Disabling this could be useful for minimal base snaps without a shell, and for statically linked binaries with no use for an environment.
after
Type: Array of string
A list of applications to be started after <app-name>. Applications must be part of the same snap. The order of the applications in the list has no effect on their launch order.
Requires daemon to be set in the app metadata. See Services and daemons for details.
See also before.
autostart⚓
Type: string
Defines the name of the .desktop file used to start an application with the desktop session.
The desktop file is placed in $SNAP_USER_DATA/.config/autostart, and the application is started using the app’s command wrapper (<name>.<app>) plus any argument present in the Exec= line within the .desktop file.
Example: autostart: my-chat.desktop
See Autostart desktop files for an example of both the desktop file and the Exec file entry.
before
Type: Array of string
An ordered list of applications to be started before <app-name> . Applications must be part of the same snap.
Requires daemon to be set in the app metadata. See Services and daemons for details.
See also after.
command
Type: string
The command to run inside the snap when <app-name> is invoked.
The command can be in either a snap runtime’s command path, $SNAP/usr/sbin:$SNAP/usr/bin:$SNAP/sbin:$SNAP/bin, or an executable path relative to $SNAP.
If daemon is set, this will be the command to run the service. Only a snap with classic confinement can use a relative path because PATH isn’t modified by a wrapper in classic confinement. See Classic confinement for more details.
Examples: app-launch for an executable placed under $SNAP/bin. With classic confinement, bin/app-launch for an executable placed under $SNAP/bin.
command-chain
Type: Array of string
A list of command to be executed, in order, before the command referenced by apps.<app-name>.command.
See Proposal: support command-chain in apps and hooks for further details.
To ensure that the Snapd distribution user running supports this feature, add the command-chain value to the assumes property.
common-id
Type: string
An identifier to a desktop-id within an external appstream file.
See Using external metadata for more details.
daemon
Type: enum
Declares that <app-name> is a system daemon.
Can be one of the following:
simple: the command is the main process.oneshot: the configured command will exit after completionforking: the configured command callsfork()as part of its start-up. The parent process is then expected to exit when start-up is completenotify: the command configured will send a signal to systemd to indicate that it’s running.
desktop
Type: string
Location of the .desktop file.
A path relative to the prime directory pointing to a desktop file, commonly used to add an application to the launch menu. Snapcraft will take care of the rest.
Examples:
usr/share/applications/my-app.desktopshare/applications/my-app.desktop
See Desktop files for menu integration for the complete details about desktop shortcuts and entries for snaps on Linux.
environment
Type: dict
A set of key-value pairs specifying the contents of environment variables.
Key is the environment variable name; Value is the contents of the environment variable.
Example: LANG: C.UTF-8
extensions
Type: list[string] | string (optional)
Snapcraft extensions enable snap developers to easily incorporate a set of common requirements into a snap, such as those to integrate an application with a desktop environment.
For further details, see Snapcraft extensions, and see Supported extensions for a full list of supported extensions.
Example: [gnome-3-38]
install-mode
Type: string
Defines whether a freshly installed daemon is started automatically, or whether startup control is deferred to the snap.
If a snap was installed prior to the daemon component being added, install-mode will determine whether or not the daemon is started automatically when the component is delivered via a snap update.
When disabled, the snap needs to use snapctl with a hook, or another management agent, to start the daemon.
Can be either of the following:
enable: the daemon is started after being installed.disable: the daemon will not be started after installation.
Defaults to enable.
Requires daemon to be set in the app metadata. See Services and daemons for details.
listen-stream
Type: string
The socket abstract name or socket path.
Sockets should go to a map of <socket-name>\ to objects which specify the listen-stream and (optionally) the socket-mode.
TCP socket syntax: <port>, [::]:<port>, [::1]:<port> and 127.0.0.1:<port>
UNIX socket syntax: $SNAP_DATA/<path>, $SNAP_COMMON/<path> and @snap.<snap name>.<suffix>
Example:
unix:
listen-stream: $SNAP_COMMON/lxd/unix.socket
socket-mode: 0660
passthrough
Type: type[object]
<app-name> attributes to pass through to snap.yaml without snapcraft validation.
See Using in-development features for further details.
plugs
Type: list[string]
Plugs for interfaces to connect to.
<app-name> will make these plug connections when running in strict confinement For interfaces that need attributes, see top-level plugs.
Example: [home, removable-media, raw-usb]
post-stop-command
Type: string
Runs a command from inside the snap after a service stops.
Requires daemon to be set in the app metadata. See Services and daemons for details.
refresh-mode
Type: string
Controls how the daemon or app should be treated during a snap refresh.
Can be either of the following:
endure: the daemon will not be restarted during a snap refresh.restart: the daemon will be restarted during a snap refresh.ignore-running: the app will not block a snap refresh (can only be set for apps).
Defaults to restart.
Requires daemon to be set in the app metadata. See Services and daemons for details.
restart-condition
Type: enum
Condition to restart the daemon under.
Defaults to on-failure. Other values are [on-failure|on-success|on-abnormal|on-abort|always|never]. Refer to systemd.service manual for details.
Requires daemon to be set in the app metadata. See Services and daemons for details.
slots
Type: list[string]
Slots for interfaces to connect to.
<app-name> will make these slot connections when running in strict confinement only. For interfaces that need attributes, see top-level slots.
Example: [home, removable-media, raw-usb]
sockets
Type: dict
Maps a daemon’s sockets to services and activates them.
Requires an activated daemon socket.
Requires apps.<app-name>.plugs to declare the network-bind plug.
socket-mode
Type: integer
The mode of a socket in octal.
stop-command
Type: string
The path to a command inside the snap to run to stop the service.
Requires daemon to be set in the app metadata. See Services and daemons for details.
stop-timeout
Type: string
The length of time to wait before terminating a service.
Time duration units can be 10ns, 10us, 10ms, 10s, 10m. Termination is via SIGTERM (and SIGKILL if that doesn’t work).
timer
Type: timer-string
Schedules when, or how often, to run a service or command.
See Timer string format for further details on the required syntax.
Requires daemon to be set in the app metadata. See Services and daemons for details.
