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nixos/modules/flake/source-info: new module #179772

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nixos/modules/flake/source-info: new module #179772

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02065ac
nixos/modules/flake/source-info: new module
herberteuler Jul 1, 2022
a2ec1c5
nixos/modules/flake/source-info: improve example and description
herberteuler Jul 15, 2022
60cfde6
nixos/modules/flake/source-info: add a section to the nixos manual
herberteuler Jul 16, 2022
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31 changes: 31 additions & 0 deletions nixos/modules/flake/source-info.nix
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Original file line number Diff line number Diff line change
@@ -0,0 +1,31 @@
{ config, lib, ... }:

with lib;

let sourceInfo = config.system.nixos.configuration.sourceInfo;

in
{
options = {

system.nixos.configuration.sourceInfo = mkOption {
type = types.attrsOf types.anything;
default = {};
example = "self.sourceInfo";
description = ''
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You could do this and then write markdown if you like

Suggested change
description = ''
description = lib.mdDoc ''

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Updated. The example also gets improved.

The source information of a flake-based NixOS configuration.
If set, the attribute <literal>configurationRevision</literal>
will appear properly in the output of
<literal>nixos-version --json</literal>.
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Doesn't it also occur in the grub and systemd-boot boot menus?

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@herberteuler herberteuler Jul 15, 2022 •
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It does not. Currently, the menus contain only the shortRev of nixpkgs. Should we add the configuration revision to versionSuffix too? If both revisions are to be included, they should be made distinctive.

Note that the nixpkgs revision can be dirty too; we may develop a uniform way to obtain revisions, and apply it to both occasions. What do you think about my earlier proposals on setting the dirty tag? I can start to work on a prototype after we discuss and reach an agreement.

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It does not.

Ok. That can be done in another PR if desirable.

we may develop a uniform way to obtain revisions

Sounds good, but these are all quite independent problems. It's best to resolve them in separate PRs, so that maintainers don't need to keep (in the limit) all of NixOS in their head in order to approve them.

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Sure, there will be at least three PRs: this one, one for obtaining revisions, and another one for applying the feature. I will try to write a detailed design later.


Caution: Setting this option may result in unnecessary
re-deployments if the flake repository changes but the
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Suggested change
re-deployments if the flake repository changes but the
boot loader entries or re-deployments if the flake repository changes but the

specific system configuration does not change.
'';
};
};

config = {
system.configurationRevision = mkIf (sourceInfo ? rev) sourceInfo.rev;
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Can we set it to "dirty" when we see that sourceInfo is from git but does not have rev?
We don't have a type-like attribute in there (yet?), but the presence of submodules should give it away.

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NixOS/nix#6747

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The intention of setting it to dirty, to my understanding, is to help identify the state of the configuration better. To answer this question well, I checked the relevant code, and have two proposals:

  1. We can do it for all supported VCSes, not just git. For instance, mercurial is also supported (albeit immature). This is partly due to only git getting special handling while examining local paths, and we may improve that too to enable support for other VCSes. This also implies a standardized, fine-grained specification of source information, as will be discussed in sourceInfo does not tell us whether it's git or not nix#6747.

  2. To further tell differences among dirty configurations, we can fetch the latest update time of a repository and set something like dirty-<timestamp>. The latest update time can be defined as the most recent modification time of all files in the repository.

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@roberth Do we solve this later as a part of NixOS/rfcs#125?

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We can scope this discussion out regardless.

};
}
1 change: 1 addition & 0 deletions nixos/modules/module-list.nix
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Expand Up @@ -38,6 +38,7 @@
./config/users-groups.nix
./config/vte.nix
./config/zram.nix
./flake/source-info.nix
./hardware/acpilight.nix
./hardware/all-firmware.nix
./hardware/bladeRF.nix
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