Invalid icon path '$SNAP/meta/gui/icon.png'


#1

Recent automated review https://dashboard.snapcraft.io/snaps/hw-probe/revisions/374/ has failed with the error:

invalid icon path '$SNAP/meta/gui/icon.png'. Should either specify the basename of the file (with or without file extension), snap.<snap name>.<snap command>[.(png|svg)] or ${SNAP}/path/to/icon.(png|svg) lint-snap-v2_desktop_file_icon (hw-probe.desktop, $SNAP/meta/gui/icon.png)

Why? How to fix this?

Desktop file is:

[Desktop Entry]
Name=Hardware Probe
Comment=Probe for hardware and upload result to the Linux hardware database
Exec=hw-probe
Icon=$SNAP/meta/gui/icon.png
Terminal=true
Type=Application
StartupNotify=true
Categories=System;
Keywords=HW Probe;Hardware;Probe;

#2

Fixed by adding install instructions for icon in snapcraft.yaml:

mkdir -p $SNAPCRAFT_PART_INSTALL/usr/share/icons/
cp -f <SRC>/icon-64x64.png $SNAPCRAFT_PART_INSTALL/usr/share/icons/hw-probe.png

And fixing a line in the desktop file:

Icon=${SNAP}/usr/share/icons/hw-probe.png

#3

Simply changing it to ${SNAP}/meta/gui/icon.png would likely have been sufficient.

The desktop file sanitisation routines in snapd only expand ${SNAP} and not $SNAP, so it is likely that your old icon line wasn’t being expanded correctly either. All that has changed is that the review tools have been updated to catch this mistake.


#4

Snapcraft prefers that you don’t prefix with ${SNAP} any more. While it will work, the preferred method is to use /usr/share/icons/hw-probe.png when your icon is in that location by considering the snap root as /. This makes it easier to support unmodified desktop files from the upstream projects, where for example if you were to use autotools and set --prefix=/usr it will install the icons relative to /usr and set their location in the desktop file (provided the autotools project is configured to do so) with the path beginning with /usr and it will “just work”.


#5

This is half true though, if you drop file under snap/{gui,hooks} snapcraft just passes them along as those are handcrafted and assumed to be correct.


#6

In terms of the review-tools and the upcoming PR from @jamesh, meta/snap.yaml (as opposed to snapcraft.yaml), cannot use absolute paths. I understood that snapcraft will translate /usr/share/icons/hw-probe.png in the snapcraft.yaml into ${SNAP}/usr/share/icons/hw-probe.png in the resulting meta/snap.yaml. @daniel and @sergiusens - is this the case? I can adjust the message accordingly based on your feedback.


#7

Yes, it’s a convenience that snapcraft handles / anchored paths. Internally under the hood it will add the ${SNAP} prefix.


#8

I’ll adjust the error message and also explicitly check for $SNAP to make it easier to spot that mistake.


#9

I said that wrong, I obviously meant the desktop files cannot use absolute paths for icons, not snap.yaml.