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Merge pull request #7382 from fricklerhandwerk/doc-automatic-uid

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move documentation on `auto-allocate-uids` to options docs
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Eelco Dolstra 2022-12-06 11:31:34 +01:00 committed by GitHub
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42
doc/manual/src/release-notes/rl-next.md
View file

@ -12,43 +12,37 @@
([#7260](https://github.com/NixOS/nix/pull/7260)).
* Nix can now automatically pick UIDs for builds, removing the need to
create `nixbld*` user accounts. These UIDs are allocated starting at
872415232 (0x34000000) on Linux and 56930 on macOS.
create `nixbld*` user accounts.
This is an experimental feature. To enable it, add the following to
`nix.conf`:
See [`auto-allocate-uids`].
```
extra-experimental-features = auto-allocate-uids
auto-allocate-uids = true
```
[`auto-allocate-uids`]: (../command-ref/conf-file.md#conf-auto-allocate-uids)
* On Linux, Nix can now run builds in a user namespace where the build
runs as root (UID 0) and has 65,536 UIDs available. This is
primarily useful for running containers such as `systemd-nspawn`
inside a Nix build. For an example, see
https://github.com/NixOS/nix/blob/67bcb99700a0da1395fa063d7c6586740b304598/tests/systemd-nspawn.nix.
runs as root (UID 0) and has 65,536 UIDs available.
A build can enable this by requiring the `uid-range` system feature,
i.e. by setting the derivation attribute
<!-- FIXME: move this to its own section about system features -->
This is primarily useful for running containers such as `systemd-nspawn`
inside a Nix build. For an example, see [`tests/systemd-nspawn/nix`][nspawn].
[nspawn]: https://github.com/NixOS/nix/blob/67bcb99700a0da1395fa063d7c6586740b304598/tests/systemd-nspawn.nix.
A build can enable this by by setting the derivation attribute:
```
requiredSystemFeatures = [ "uid-range" ];
```
The `uid-range` system feature requires the `auto-allocate-uids`
setting to be enabled (see above).
The `uid-range` [system feature] requires the [`auto-allocate-uids`]
setting to be enabled.
[system feature]: (../command-ref/conf-file.md#conf-system-features),
* On Linux, Nix has experimental support for running builds inside a
cgroup. It can be enabled by adding
cgroup.
```
extra-experimental-features = cgroups
use-cgroups = true
```
to `nix.conf`. Cgroups are required for derivations that require the
`uid-range` system feature.
See [`use-cgroups`](../command-ref/conf-file.md#conf-use-cgroups).
* `nix build --json` now prints some statistics about top-level
derivations, such as CPU statistics when cgroups are enabled.

38
src/libstore/globals.hh
View file

@ -284,7 +284,22 @@ public:
)"};
Setting<bool> autoAllocateUids{this, false, "auto-allocate-uids",
"Whether to allocate UIDs for builders automatically."};
R"(
Whether to select UIDs for builds automatically, instead of using the
users in `build-users-group`.
UIDs are allocated starting at 872415232 (0x34000000) on Linux and 56930 on macOS.
> **Warning**
> This is an experimental feature.
To enable it, add the following to [`nix.conf`](#):
```
extra-experimental-features = auto-allocate-uids
auto-allocate-uids = true
```
)"};
Setting<uint32_t> startId{this,
#if __linux__
@ -308,11 +323,22 @@ public:
Setting<bool> useCgroups{
this, false, "use-cgroups",
R"(
Whether to execute builds inside cgroups. Cgroups are
enabled automatically for derivations that require the
`uid-range` system feature.
)"
};
Whether to execute builds inside cgroups.
This is only supported on Linux.
Cgroups are required and enabled automatically for derivations
that require the `uid-range` system feature.
> **Warning**
> This is an experimental feature.
To enable it, add the following to [`nix.conf`](#):
```
extra-experimental-features = cgroups
use-cgroups = true
```
)"};
#endif
Setting<bool> impersonateLinux26{this, false, "impersonate-linux-26",