Show interfaces of snap before installation

snapd
1

Is it possible to list which interfaces a snap provides/requires before installing it?

2 Likes
2

Not easily.

alan@KinkPad-K450:~/Temp/foo$ snap download emoj
Fetching snap "emoj"
Fetching assertions for "emoj"
Install the snap with:
   snap ack emoj_53.assert
   snap install emoj_53.snap
alan@KinkPad-K450:~/Temp/foo$ unsquashfs emoj_53.snap meta/snap.yaml
Parallel unsquashfs: Using 4 processors
1 inodes (1 blocks) to write

[===================================================================|] 1/1 100%

created 1 files
created 2 directories
created 0 symlinks
created 0 devices
created 0 fifos
alan@KinkPad-K450:~/Temp/foo$ cat squashfs-root/meta/snap.yaml 
name: emoj
version: v2.0.0
summary: emoj
description: 'Find relevant emoji from text on the command-line.

  '
architectures:
- amd64
confinement: strict
grade: stable
apps:
  emoj:
    command: command-emoj.wrapper
    plugs:
    - network
    - x11
1 Like
3

Depending on what you’re trying to do, the store does expose that information (and snapd does use it, but does not expose it) via the snap-yaml field. It has some caveats but, for example, you can do

http https://api.snapcraft.io/v2/snaps/info/emoj \
Snap-Device-Series:16 architecture==amd64 fields==snap-yaml |
jq -r '."channel-map"[0]."snap-yaml"'

which produces

name: emoj
version: v2.0.0
summary: emoj
description: 'Find relevant emoji from text on the command-line.

  '
architectures:
- amd64
confinement: strict
grade: stable
apps:
  emoj:
    command: command-emoj.wrapper
    plugs:
    - network
    - x11
3 Likes
4

I think we should implement this, and the companion “find things that have these plugs/slots/interfaces”, but I’m not sure what would be a reasonable UX for it from snap find, or snap info. Ideas?

5

Also see lp:1776938.

6

A somewhat related proposal to the request is here: Install snap without any auto-connections proposal

If we had that, at least for snaps one is unsure about, you could install it without any interfaces connected, then inspect with snap connections to see all the possible connections for that snap.

7

I know this thread is old, but not knowing which interfaces a snap by an unknown publisher uses is why I am reluctant to try out new snaps.

It would be great to have this information shown within the web store and/or the snap command.