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.
When computing a lock file, we now respect the lock files of flake
inputs. This is important for usability / reproducibility. For
example, the 'nixops' flake depends on the 'nixops-aws' and
'nixops-hetzner' repositories. So when the 'nixops' flake is used in
another flake, we want the versions of 'nixops-aws' and
'nixops-hetzner' locked by the the 'nixops' flake because those
presumably have been tested.
This can lead to a proliferation of versions of flakes like 'nixpkgs'
(since every flake's lock file could depend on a different version of
'nixpkgs'). This is not a major issue when using Nixpkgs overlays or
NixOS modules, since then the top-level flake composes those
overlays/modules into *its* version of Nixpkgs and all other versions
are ignored. Lock file computation has been made a bit more lazy so it
won't try to fetch all those versions of 'nixpkgs'.
However, in case it's necessary to minimize flake versions, there now
are two input attributes that allow this. First, you can copy an input
from another flake, as follows:
inputs.nixpkgs.follows = "dwarffs/nixpkgs";
This states that the calling flake's 'nixpkgs' input shall be the same
as the 'nixpkgs' input of the 'dwarffs' input.
Second, you can override inputs of inputs:
inputs.nixpkgs.url = github:edolstra/nixpkgs/<hash>;
inputs.nixops.inputs.nixpkgs.url = github:edolstra/nixpkgs/<hash>;
or equivalently, using 'follows':
inputs.nixpkgs.url = github:edolstra/nixpkgs/<hash>;
inputs.nixops.inputs.nixpkgs.follows = "nixpkgs";
This states that the 'nixpkgs' input of the 'nixops' input shall be
the same as the calling flake's 'nixpkgs' input.
Finally, at '-v' Nix now prints the changes to the lock file, e.g.
$ nix flake update ~/Misc/eelco-configurations/hagbard
inputs of flake 'git+file:///home/eelco/Misc/eelco-configurations?subdir=hagbard' changed:
updated 'nixpkgs': 'github:edolstra/nixpkgs/7845bf5f4b3013df1cf036e9c9c3a55a30331db9' -> 'github:edolstra/nixpkgs/03f3def66a104a221aac8b751eeb7075374848fd'
removed 'nixops'
removed 'nixops/nixops-aws'
removed 'nixops/nixops-hetzner'
removed 'nixops/nixpkgs'
On a systemd-based Linux distribution: If the user has previously had multi-user Nix installed on the system, removed it and then reinstalled multi-user Nix again the old nix-daemon.service will still be running when `scripts/install-systemd-multi-user.sh` tries to start it which results in nothing being done and the old daemon continuing its run.
When a normal user then tries to use Nix through the daemon the nix binary will fail to connect to the nix-daemon as it does not belong to the currently installed Nix system. See below for steps to reproduce the issue that motivated this change.
$ sh <(curl https://nixos.org/nix/install) --daemon
$ sudo rm -rf /etc/nix /nix /root/.nix-profile /root/.nix-defexpr /root/.nix-channels /home/nix-installer/.nix-profile /home/nix-installer/.nix-defexpr /home/nix-installer/.nix-channels ~/.nix-channels ~/.nix-defexpr/ ~/.nix-profile /etc/profile.d/nix.sh.backup-before-nix /etc/profile.d/nix.sh; sed -i '/added by Nix installer$/d' ~/.bash_profile
$ unset NIX_REMOTE
$ sh <(curl https://nixos.org/nix/install) --daemon
└$ export NIX_REMOTE=daemon
└$ nix-env -iA nixpkgs.hello
installing 'hello-2.10'
error: cannot connect to daemon at '/nix/var/nix/daemon-socket/socket': No such file or directory
(use '--show-trace' to show detailed location information)
└$ sudo systemctl restart nix-daemon.service
└$ nix-env -iA nixpkgs.hello
installing 'hello-2.10'
these paths will be fetched (6.09 MiB download, 27.04 MiB unpacked):
/nix/store/2g75chlbpxlrqn15zlby2dfh8hr9qwbk-hello-2.10
/nix/store/aag9d1y4wcddzzrpfmfp9lcmc7skd7jk-glibc-2.27
copying path '/nix/store/aag9d1y4wcddzzrpfmfp9lcmc7skd7jk-glibc-2.27' from 'https://cache.nixos.org'...
copying path '/nix/store/2g75chlbpxlrqn15zlby2dfh8hr9qwbk-hello-2.10' from 'https://cache.nixos.org'...
building '/nix/store/w9adagg6vlikr799nkkqc9la5hbbpgmi-user-environment.drv'...
created 2 symlinks in user environment
Fixes
error: derivation '/nix/store/klivma7r7h5lndb99f7xxmlh5whyayvg-zlib-1.2.11.drv' has incorrect output '/nix/store/fv98nnx5ykgbq8sqabilkgkbc4169q05-zlib-1.2.11-dev', should be '/nix/store/adm7pilzlj3z5k249s8b4wv3scprhzi1-zlib-1.2.11-dev'
- At the top of the release notes, we announce sandboxing is now enabled by default,
then at the bottom it says it's now disabled when missing kernel support. These
can be merged into one point for clarity.
- The point about `max-jobs` defaulting to 1 appears unrelated to sandboxing.
Includes the expression of the condition in the assertion message if
the assertion failed, making assertions much easier to debug. eg.
error: assertion (withPython -> (python2Packages != null)) failed at pkgs/tools/security/nmap/default.nix:11:1
