nix-daemon.socket is used to socket-activate nix-daemon.service when
/nix/var/nix/daemon-socket/socket is accessed.
In container usecases, sometimes /nix/var/nix/daemon-socket is
bind-mounted read-only into the container.
In these cases, we want to skip starting nix-daemon.socket.
However, since systemd 250, `ConditionPathIsReadWrite` is also not met
if /nix/var/nix/daemon-socket doesn't exist at all. This means, a
regular NixOS system will skip starting nix-daemon.socket:
> [ 237.187747] systemd[1]: Nix Daemon Socket was skipped because of a failed condition check (ConditionPathIsReadWrite=/nix/var/nix/daemon-socket).
To prevent this from happening, ship a tmpfiles file that'll cause the
directory to be created if it doesn't exist already.
In the case of NixOS, we can just add Nix to `systemd.tmpfiles.packages`
and have these files picked up automatically.
1. `DerivationOutput` now as the `std::variant` as a base class. And the
variants are given hierarchical names under `DerivationOutput`.
In 8e0d0689be @matthewbauer and I
didn't know a better idiom, and so we made it a field. But this sort
of "newtype" is anoying for literals downstream.
Since then we leaned the base class, inherit the constructors trick,
e.g. used in `DerivedPath`. Switching to use that makes this more
ergonomic, and consistent.
2. `store-api.hh` and `derivations.hh` are now independent.
In bcde5456cc I swapped the dependency,
but I now know it is better to just keep on using incomplete types as
much as possible for faster compilation and good separation of
concerns.
Before the change garbage collector was not considering
`.drv` and outputs as alive even if configuration says otherwise.
As a result `nix store gc --dry-run` could visit (and parse)
`.drv` files multiple times (worst case it's quadratic).
It happens because `alive` set was populating only runtime closure
without regard for actual configuration. The change fixes it.
Benchmark: my system has about 139MB, 40K `.drv` files.
Performance before the change:
$ time nix store gc --dry-run
real 4m22,148s
Performance after the change:
$ time nix store gc --dry-run
real 0m14,178s
Don’t try and assume that we know the output paths when we’ve just built
with `--dry-run`. Instead make `--dry-run` follow a different code path
that won’t assume the knowledge of the output paths at all.
Fix#6275
The current `--out-path` flag has two disadvantages when one is only
concerned with querying the names of outputs:
- it requires evaluating every output's `outPath`, which takes
significantly more resources and runs into more failures
- it destroys the information of the order of outputs so we can't tell
which one is the main output
This patch makes the output names always present (replacing paths with
`null` in JSON if `--out-path` isn't given), and adds an `outputName`
field.
When importing e.g. a local `nixpkgs` in a flake to test a change like
{
inputs.nixpkgs.url = path:/home/ma27/Projects/nixpkgs;
outputs = /* ... */
}
then the input is missing a `lastModified`-field that's e.g. used in
`nixpkgs.lib.nixosSystem`. Due to the missing `lastMoified`-field, the
mtime is set to 19700101:
result -> /nix/store/b7dg1lmmsill2rsgyv2w7b6cnmixkvc1-nixos-system-nixos-22.05.19700101.dirty
With this change, the `path`-fetcher now sets a `lastModified` attribute
to the `mtime` just like it's the case in the `tarball`-fetcher already.
When building NixOS systems with `nixpkgs` being a `path`-input and this
patch, the output-path now looks like this:
result -> /nix/store/ld2qf9c1s98dxmiwcaq5vn9k5ylzrm1s-nixos-system-nixos-22.05.20220217.dirty
Before the change on a system with `auto-optimise-store = true`:
$ nix store gc --verbose --max 1
deleted all the paths instead of one path (we requested 1 byte limit).
It happens because every file in `auto-optimise-store = true` has at
least 2 links: file itself and a link in /nix/store/.links/ directory.
The change conservatively assumes that any file that has one (as before)
or two links (assume auto-potimise mode) will free space.
Co-authored-by: Sandro <sandro.jaeckel@gmail.com>
help new users find a solution to their problem
./result/bin/nix-env -qa hello
warning: name collision in input Nix expressions, skipping '/home/artturin/.nix-defexpr/channels_root/master'
suggestion: remove 'master' from either the root channels or the user channels
hello-2.12
hello-2.12
