Future editions of flakes or the Nix language can be supported by
renaming flake.nix (e.g. flake-v2.nix). This avoids a bootstrap
problem where we don't know which grammar to use to parse
flake*.nix. It also allows a project to support multiple flake
editions, in theory.
This is useful for finding out what a registry lookup resolves to, e.g
$ nix flake info patchelf
Resolved URL: github:NixOS/patchelf
Locked URL: github:NixOS/patchelf/cd7955af31698c571c30b7a0f78e59fd624d0229
When we do something like 'nix flake update --override-input nixpkgs
...', the override is now kept on subsequent calls. (If you don't want
this behaviour, you can use --no-write-lock-file.)
This is now done in a single pass. Also fixes some issues when
updating flakes with circular dependencies. Finally, when using
'--recreate-lock-file --commit-lock-file', the commit message now
correctly shows the differences.
This improves reproducibility and may be faster than fetching from the
original source (especially for git/hg inputs, but probably also for
github inputs - our binary cache is probably faster than GitHub's
dynamically generated tarballs).
Unfortunately this doesn't work for the top-level flake since even if
we know the NAR hash of the tree, we don't know the other tree
attributes such as revCount and lastModified.
Fixes#3253.
Typical usage:
$ nix flake update ~/Misc/eelco-configurations/hagbard --update-input nixpkgs
to update the 'nixpkgs' input of a flake while leaving every other
input unchanged.
The argument is an input path, so you can do e.g. '--update-input
dwarffs/nixpkgs' to update an input of an input.
Fixes#2928.
Added a flag --no-update-lock-file to barf if the lock file needs any
changes. This is useful for CI systems if you're building a
checkout. Fixes#2947.
Renamed --no-save-lock-file to --no-write-lock-file. It is now a fatal
error if the lock file needs changes but --no-write-lock-file is not
given.
E.g.
$ nix flake update ~/Misc/eelco-configurations/hagbard \
--override-input 'dwarffs/nixpkgs' ../my-nixpkgs
overrides the 'nixpkgs' input of the 'dwarffs' input of the top-level
flake.
Fixes#2837.
