Define additional metadata in .desktop file

[probonopd]

The topmost .desktopfile in the root directory of the AppDir/AppImage should be enriched with additional lightweight metadata related to the AppImage.

http://standards.freedesktop.org/desktop-entry-spec/latest/ar01s11.html

PortableLinuxGames apparently already has defined some.

• X-AppImage-Name: Name of the application (e.g., Krita)
• X-AppImage-Version: Version of the application that is contained in the AppImage (e.g., 1.3.1)
• X-AppImage-Arch: Architecture of the AppImage (e.g., x86_64)
• X-AppImage-Release: Version or timestamp of the AppImage itself (added at AppImage creation time)
  ...

However. let's try not to be redundant to AppStream information. So let's not include the license, the URL, etc.

[probonopd]

X-AppImage-Version might be misleading since it is not evident that this is about the payload app

[TheAssassin]

I think we can close this, since there's support for AppStream, which we propose in a lot of places, including AppImageHub. As far as I know, it has support for a lot of default types, and also allows auxiliary information.

[probonopd]

But it is optional and cumbersome whereas adding the version of the application should be easy/automatic...

[azubieta]

I guess that this should be solved by the conclusions of this discussion: AppImageCommunity/appimaged#30 therefore I'll close the issue.

Re-open it if you think otherwise :)

[probonopd]

AppImageCommunity/appimaged#30 names some metadata which currently is not in desktop files yet (but may be required for the proper functioning of the concepts outlined in AppImageCommunity/appimaged#30). At this point it is unclear whether an extension of the current desktop file format is the way to go, or a switch to something like JSON or YAML (which would allow for plist-style data structures like arrays etc.)

[probonopd]

Let's close this only after we have documented this stuff somewhere.

[TheAssassin]

I don't see why there's a need for another name field. We already have version support. There's no need to put the architecture in the desktop file. And the timestamp of the AppImage creation isn't really anything a user needs to worry about.

There is nothing to discuss in here any more, the version part has been implemented long ago.

[probonopd]

X-AppImage-Version is currently undocumented, isn't it? (Where is it documented/specified?)

[probonopd]

Same for the architecture?

[probonopd]

Reference: #662

[TheAssassin]

Many features are undocumented right now. Please open an issue in the docs repository.

[probonopd]

Thank you for documenting them. Should we also add them to the AppImageSpec?

[TheAssassin]

If you like. I'm not entirely sure which are even supported, so I stayed a bit vague. After all, I only know for sure X-AppImage-Version is actively used.

I don't think that stuff needs to go in the spec necessarily, but if you like, you can put it in as a recommendation (SHOULD). That's probably more motivation for anyone than the docs to implement this in their tools.