Interfaces allow snaps to communicate or share resources according to the protocol established by the interface. Each connection has two ends, a “plug” (consumer) and a “slot” (provider). A plug and a slot can be connected if they use the same interface name. The connection grants necessary permissions for snaps to operate according to the protocol.
For example, a snap using the camera can declare it requires the
camera interface. On the other end of the connection, the core snap declares it provides the
camera interface. When the interface gets connected, the snap gets read access to
Slots may support multiple connections to plugs. For example the core snap
network slot and all applications that can talk over the
network connect their plugs there.
The availability of an interface depends on a number of factors and may be
provided by the core snap or via snaps providing the slot. The available
interfaces on a given system can be seen with
A complete list of interfaces is provided in the Interfaces reference. You can also see the list of interfaces available on a system and the snaps using them with
snap interfaces or use the command to get more specific information, including:
snap interfaces <snap>to find the slots offered and plugs used by the specified snap.
snap interfaces <snap>:<slot or plug>for details of only the specified slot or plug.
snap interfaces -i=<interface> [<snap>]to get a filtered list of plugs and/or slots.
Most interfaces are designed for strong application isolation and user control such that auto-connected interfaces are considered safe and users choose what applications to trust and to what extent via manually connected interfaces.
Some interfaces are considered transitional to support traditional Linux desktop environments and these transitional interfaces typically are auto-connected. Since many of the underlying technologies in these environments were not designed with strong application isolation in mind, users should only install applications using these interfaces from trusted sources. Transitional interfaces will be deprecated as replacement or modified technologies that enforce strong application isolation are available.
There are, however, some interfaces which are not automatically connected. The user is still free to connect these manually (see below), but the snap developer can also request that a given interface be automatically connected for their snap. This involves a more thorough security vetting process, and justification for using the interfaces in question. To make this request, create a new topic in the store category of the forum, describing your snap and justifying your use of a privileged interface.
Creating an interface
The OS snap exposes a number of interfaces to grant snaps access to system functions. You can extend this access by creating your own interfaces.
The following tutorial will show you how: Your first interface.
Requesting an interface
You can also file an interface request by opening a bug report with the
snapd-interface bug tag.
Manually connecting interfaces
Interfaces may either be auto-connected by
snapd on install or manually connected after
To list the available connectable interfaces and connections:
$ snap interfaces
To make a connection:
$ snap connect <snap>:<plug interface> <snap>:<slot interface>
To disconnect snaps:
$ snap disconnect <snap>:<plug interface> <snap>:<slot interface>
Consider a snap
foo that uses
plugs: [ log-observe ]. Since
log-observe is not auto-connected,
foo will not have access to the
interface upon install:
$ sudo snap install foo $ snap interfaces Slot Plug :log-observe - - foo:log-observe
You may manually connect using
$ sudo snap connect foo:log-observe core:log-observe $ snap interfaces Slot Plug :log-observe foo:log-observe
and disconnect using
$ sudo snap disconnect foo:log-observe core:log-observe $ snap interfaces # shows they are disconnected Slot Plug :log-observe - - foo:log-observe
On the other hand,
bar could use
plugs: [ network ] and since
network is auto-connected,
bar has access to the interface upon
$ sudo snap install bar $ snap interfaces Slot Plug :network bar:network
You may disconnect an auto-connected interface:
$ sudo snap disconnect bar:network core:network $ snap interfaces Slot Plug :network - - bar:network
Whether the slot is provided by the core snap or not doesn’t matter in terms of
snap interfaces except that if the slot is provided by a snap, a snap that
implements the slot must be installed for it to be connectable. Eg, the
bluez interface is not provided by the core snap so a snap author
implementing the bluez service might use
slots: [ bluez ]. Then after
install, the bluez interface shows up as available:
$ sudo snap install foo-blue $ snap interfaces Slot Plug foo-blue:bluez -
Now install and connect works like before (eg,
plugs: [ bluez ]):
$ sudo snap install baz $ snap interfaces Slot Plug foo-blue:bluez - - baz:bluez $ sudo snap connect baz:bluez foo-blue:bluez $ snap interfaces Slot Plug foo-blue:bluez baz:bluez