Feature Request: Support .sources files

[snoack]

New Feature

Since Debian Trixie, apt supports .sources files replacing old .list files, and shows a message to run apt modernize-sources to convert your old .list files. deb-get only supports .list files which isn't ideal.

[philclifford]

"Debian 13 (Trixie) marks the transition to the DEB822 (.sources) format as the default for managing repositories. The roadmap involves an automated migration path using apt modernize-sources to convert old .list files into structured, key-value .sources files, with full legacy support expected to last until at least 2029. "

"Deprecation Timeline: While DEB822 is the new standard, legacy sources.list format support is planned to continue for several years to allow for smooth migration."

apt 1.1 has supported DEB822 since ~2015
apt modernize-sources appears in apt 2.9.26 (noble currently has 2.8.3)

We should try to built support for DEB822 but there's no rush.

I'd suggest that we could

• build support for creating new .sources when running on trixie+ or noble+ hosts while retaining .list behaviour on hosts based on earlier upstream releases (to match the switch to default)
• start with an option (ENV based ?) the user can opt into (later changing the default over)
• allow the option to be used on earlier releases (jammy and bookworm fully supports DEB822 )

I feel we should

• NOT consider running apt modernize-sources or similar ourselves - that is something a user should choose to do
• ensure that applications/upstreams that use/specify old .list format are respected and supported (there have been problems with some apps/repos and some distro tools )
• ensure that we are sensitive to the needs of deb-get users on non-Ubuntu platforms
• remember some repos will use debs to update their own .lists (and convert them to DEB822 .sources )