There are a bunch of components such as incus or LXC that also use
`boot.isContainer`, so we'd have to differentiate between "OS container"
and "actually nspawn".
This became necessary for the file-systems part where nspawn takes care
of setting up special filesystems like `/proc`, `/dev` etc., but others
don't.
To allow for a `boot.isContainer` being less overloaded, this introduces
`boot.isNspawnContainer` that is exclusively used for nspawn-specific
things. When `true`, `boot.isContainer = true;` is implied.
Integrated the flake container setup into the spawn script for systemd-nspawn.
The trickiest part of this was ensuring the underlying per-container is built.
With the .conf file created, running `nixos-container update` creates all the necessary per-container structure.
We call this command at start to ensure the structure is created only if the per-container system isnt there.
Note: This also means the flake gets updated to branch HEAD when the container is started for the first time.
While the nixos-container command allows for the creation of containers pointing to a flake, the declarative module doesn't have this option.
Adds the flake option for nixos-container declarative approach. Creates the /etc/nixos-container .conf file similar to how the command preforms it.
Format all Nix files using the officially approved formatter,
making the CI check introduced in the previous commit succeed:
nix-build ci -A fmt.check
This is the next step of the of the [implementation](https://github.com/NixOS/nixfmt/issues/153)
of the accepted [RFC 166](https://github.com/NixOS/rfcs/pull/166).
This commit will lead to merge conflicts for a number of PRs,
up to an estimated ~1100 (~33%) among the PRs with activity in the past 2
months, but that should be lower than what it would be without the previous
[partial treewide format](https://github.com/NixOS/nixpkgs/pull/322537).
Merge conflicts caused by this commit can now automatically be resolved while rebasing using the
[auto-rebase script](8616af08d9/maintainers/scripts/auto-rebase).
If you run into any problems regarding any of this, please reach out to the
[formatting team](https://nixos.org/community/teams/formatting/) by
pinging @NixOS/nix-formatting.
I think this is the norm in NixOS modules. This allows to start a
container with '--volatile=overlay --link-journal=host' in order to
persist logs across runs of a container running with a temporary root.
While '--ephemeral' omits '--link-journal=try-guest', it's not possible
to run an ephemeral container when linking the journal:
https://github.com/systemd/systemd/issues/1666
The description for options.nixpkgs.system already hints at this:
Neither ${opt.system} nor any other option in nixpkgs.* is meant
to be read by modules and configurations.
Use pkgs.stdenv.hostPlatform instead.
We can support this goal by not elaborating the systems anymore, forcing
users to go via pkgs.stdenv.
This will prevent problems when making the top-level package sets
composable in the next commit. For this to work, you should pass a fully
elaborated system to nixpkgs' localSystem or crossSystem options.
`/etc/os-release` of NixOS containers, which are
`/var/lib/nixos-containers/*/etc/os-release` on the host, are usually
symlinks to the absolute path `/etc/static/os-release` but it doesn't
exist in non-NixOS host. Since `startScript` is evaluated by the host
system, both `[ -e "$root/etc/os-release" ]` and
`touch "$root/etc/os-release"` fail, so that the container fails to
start on the second boot (on the first boot, the symlink doesn't exist,
so the command succeeds).
This commit avoids `touch "$root/etc/os-release"` if
`$root/etc/os-release` is a symlink, so imperative NixOS containers are
usable on non-NixOS host.
The minimum reproduction for the problem I'm trying to solve is that
the following NixOS test with a trivial NixOS container:
```
{ inputs = {
nixpkgs.url = "github:NixOS/nixpkgs/24.05";
flake-utils.url = "github:numtide/flake-utils/v1.0.0";
};
outputs = { flake-utils, nixpkgs, self, ... }:
flake-utils.lib.eachDefaultSystem (system: {
checks.default = nixpkgs.legacyPackages."${system}".nixosTest {
name = "test";
nodes.machine.containers.tutorial.config = { };
testScript = "";
};
});
}
```
… fails with the following error message:
```
error: Neither nodes.machine.nixpkgs.hostPlatform nor the legacy option nodes.machine.nixpkgs.system has been set.
You can set nodes.machine.nixpkgs.hostPlatform in hardware-configuration.nix by re-running
a recent version of nixos-generate-config.
The option nodes.machine.nixpkgs.system is still fully supported for NixOS 22.05 interoperability,
but will be deprecated in the future, so we recommend to set nodes.machine.nixpkgs.hostPlatform.
```
The root of the problem appears to be that in
`nixos/modules/virtualisation/nixos-containers.nix` there is support
for deriving the guest's `nixpkgs.hostPlatform` or
`nixpkgs.localSystem` from the corresponding host's values, but this
doesn't work if the host sets `nixpkgs.pkgs` instead of one of those
values. In fact, this is what happens when using `pkgs.nixosTest`
(which sets `nixpkgs.pkgs` in
`pkgs/build-support/testers/default.nix`).
The solution I went with was to forward the `nixpkgs.pkgs` setting from
the host to the guest, but only if it is defined (matching the same
treatment as `nixpkgs.hostPlatform` and `nixpkgs.localSystem`.
these changes were generated with nixq 0.0.2, by running
nixq ">> lib.mdDoc[remove] Argument[keep]" --batchmode nixos/**.nix
nixq ">> mdDoc[remove] Argument[keep]" --batchmode nixos/**.nix
nixq ">> Inherit >> mdDoc[remove]" --batchmode nixos/**.nix
two mentions of the mdDoc function remain in nixos/, both of which
are inside of comments.
Since lib.mdDoc is already defined as just id, this commit is a no-op as
far as Nix (and the built manual) is concerned.
This commit makes auto-restarting declarative containers optional.
This is useful when you don't want changes to your config to automatically
restart the container and thus stop any applications running inside it.
Calling `eval-config.nix` without a `system` from a Nix flake fails with
`error: attribute 'currentSystem' missing` since #230523. Setting
`system = null` removes the use of `currentSystem` and instead uses the
value from the `nixpkgs` module.
Use hostPlatform if both the host and the containers nixpkgs supports
hostPlatform, otherwise fall back to localSystem. This preseves backwards
compatibility.
