environment sections are reordered

[Zygmunt Krynicki]

Snapcraft cannot reorder environment sections. This applies both to snap-wide and app-specific environment sections. This matters because those entries can refer to earlier definitions and snapd implements this semantics precisely.

In particular:

name: ...
version: ...
environment:
  B: correct
  A: $B

Expands, via snapd, to B=correct, A=correct

When re-ordered alphabetically this property is lost.

[Sergio Schvezov (sergiusens)]

Well, this is exactly what YAML is https://yaml.org/spec/1.2/spec.html#id2765608

If you wanted order, then you should allow a sequence as input.

[Samuele Pedroni (pedronis)]

we might decide to change the syntax to at least deprecate the current syntax in snap.yaml (though basically we'll have to keep supporting it) and prefer

- VAR1: VALUE1
- VAR2: VALUE2

but I don't see this happen quickly.

snapcraft.yaml could be slightly more aggressive in switching over