nixos/modules/flake/source-info: new module by herberteuler · Pull Request #179772 · NixOS/nixpkgs

herberteuler · 2022-07-01T04:51:12Z

Description of changes

This PR introduces a new module that improves configurationRevision handling as discussed in #178837.

This option can be set as in the following example:

{
  inputs.nixpkgs.url = ...;
  outputs = { self, nixpkgs }: {
    nixosConfigurations = {
      host1 = nixpkgs.lib.nixosSystem {
        system = ...;
        modules = [
          { system.nixos.configuration.sourceInfo = self.sourceInfo; }
        ] ++ ...;
      };
    };
  };
}

See more details in the module description.

Things done

roberth · 2022-07-01T13:30:04Z

nixos/modules/flake/source-info.nix

+  };
+
+  config = {
+    system.configurationRevision = mkIf (sourceInfo ? rev) sourceInfo.rev;


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.

NixOS/nix#6747

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:

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.

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.

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

We can scope this discussion out regardless.

roberth · 2022-07-01T13:43:57Z

host1 = nixpkgs.lib.nixosSystem {
system = ...;

Plug: system shouldn't be necessary when specified in a module or in hardware-configuration.nix (merged).

herberteuler · 2022-07-06T01:33:42Z

host1 = nixpkgs.lib.nixosSystem {
system = ...;

Plug: system shouldn't be necessary when specified in a module or in hardware-configuration.nix (merged).

I am using nixos-22.05, perhaps I should switch to unstable...

roberth · 2022-07-06T06:30:48Z

We could avoid storing the rev in the derivation output and make the non-derivation parts of NixOS responsible for propagating this information. NixOS/rfcs#125 (comment)

roberth · 2022-07-13T12:39:21Z

nixos/modules/flake/source-info.nix

+      type = types.attrsOf types.anything;
+      default = {};
+      example = "self.sourceInfo";
+      description = ''


You could do this and then write markdown if you like

Suggested change

description = ''

description = lib.mdDoc ''

Updated. The example also gets improved.

roberth · 2022-07-13T12:40:26Z

nixos/modules/flake/source-info.nix

+        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>.


Doesn't it also occur in the grub and systemd-boot boot menus?

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.

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.

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.

roberth · 2022-07-13T12:41:06Z

nixos/modules/flake/source-info.nix

+        <literal>nixos-version --json</literal>.
+
+        Caution: Setting this option may result in unnecessary
+        re-deployments if the flake repository changes but the


Suggested change

re-deployments if the flake repository changes but the

boot loader entries or re-deployments if the flake repository changes but the

roberth · 2022-07-15T07:52:29Z

Implementation lgtm. I think we'll need to create a section in the NixOS manual as well. There currently isn't one, but that's going to be a problem when flakes are released. If we're going to write those docs last minute, they'll be incomplete, and probably skip over this feature.

herberteuler · 2022-07-16T10:39:11Z

Implementation lgtm. I think we'll need to create a section in the NixOS manual as well. There currently isn't one, but that's going to be a problem when flakes are released. If we're going to write those docs last minute, they'll be incomplete, and probably skip over this feature.

I just checked that the missing docs were not only flakes for NixOS but also flakes for Nix. But, unfortunately, writing a whole bunch of such docs is out of my reach right now. Hence I added a section for this feature but did not integrate it into the current NixOS manual. This way, someone will notice that it is there in the future.

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

02065ac

github-actions bot added 6.topic: nixos Issues or PRs affecting NixOS modules, or package usability issues specific to NixOS 8.has: module (update) This PR changes an existing module in `nixos/` labels Jul 1, 2022

ofborg bot added 10.rebuild-darwin: 0 This PR does not cause any packages to rebuild on Darwin. 10.rebuild-linux: 1-10 This PR causes between 1 and 10 packages to rebuild on Linux. labels Jul 1, 2022

roberth reviewed Jul 1, 2022

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roberth mentioned this pull request Jul 1, 2022

sourceInfo does not tell us whether it's git or not NixOS/nix#6747

Open

roberth reviewed Jul 13, 2022

View reviewed changes

nixos/modules/flake/source-info: improve example and description

a2ec1c5

nixos/modules/flake/source-info: add a section to the nixos manual

60cfde6

github-actions bot added the 8.has: documentation This PR adds or changes documentation label Jul 16, 2022

roberth mentioned this pull request Aug 18, 2022

[RFC 0125]: Use an intermediary representation (bootspec) for bootloader backends NixOS/rfcs#125

Merged

wegank added the 2.status: stale https://github.com/NixOS/nixpkgs/blob/master/.github/STALE-BOT.md label Mar 19, 2024

	re-deployments if the flake repository changes but the
	boot loader entries or re-deployments if the flake repository changes but the

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herberteuler commented Jul 1, 2022

Description of changes

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roberth commented Jul 1, 2022

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herberteuler commented Jul 6, 2022

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roberth commented Jul 6, 2022

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herberteuler Jul 15, 2022 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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roberth commented Jul 15, 2022

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herberteuler commented Jul 16, 2022

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herberteuler Jul 15, 2022 •

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