take this slightly modified example from https://github.com/zhaofengli/colmena/blob/v0.4.0/src/nix/hive/tests/makehive-flake/flake.nix

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    colmena.url = "github:zhaofengli/colmena";
  };
  outputs = { nixpkgs, colmena, ... }: rec {
    colmenaHive = colmena.lib.makeHive {
      meta = {
        nixpkgs = import nixpkgs {
          system = "x86_64-linux";
        };
      };

      host-a = { name, nodes, pkgs, ... }: {
        boot.isContainer = true;
        time.timeZone = nodes.host-b.config.time.timeZone;
      };
      host-b = {
        deployment = {
          targetHost = "somehost.tld";
          targetPort = 1234;
          targetUser = "luser";
        };
        boot.isContainer = true;
        time.timeZone = "America/Los_Angeles";
      };
    };
    nixosConfigurations = colmenaHive.nodes;
  };
}

the diff to the upstream test is:

diff --git a/upstream-flake.nix b/flake.nix
index 11c7f62..a1f59d7 100644
--- a/upstream-flake.nix
+++ b/flake.nix
@@ -1,9 +1,9 @@
 {
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
-    colmena.url = "git+file://@repoPath@";
+    colmena.url = "github:zhaofengli/colmena";
   };
-  outputs = { nixpkgs, colmena, ... }: {
+  outputs = { nixpkgs, colmena, ... }: rec {
     colmenaHive = colmena.lib.makeHive {
       meta = {
         nixpkgs = import nixpkgs {
@@ -25,5 +25,6 @@
         time.timeZone = "America/Los_Angeles";
       };
     };
+    nixosConfigurations = colmenaHive.nodes;
   };
 }

you can then use nix v3 (unstable) cli and nixos-rebuild as you wish:

❯ nixos-rebuild --flake .#host-a build
building the system configuration...
trace: warning: system.stateVersion is not set, defaulting to 24.05. Read why this matters on https://nixos.org/manual/nixos/stable/options.html#opt-system.stateVersion.

you can also mix colmena nodes and your "vanilla" lib.nixosSystem in nixosConfigurations that way (for use with nixos-rebuild):

https://git.geklaute.cloud/emilylange/nixos-config/src/commit/22570786b24b606484447bef7a29fe565d475db7/flake.nix#L48-L76

Is there a good way to convert from a flake's nixosConfigurations output to a colemena node? At the moment, I'm using this, but it seems fairly hacky:

  mkColmenaNode = node: {
    deployment = {
      targetHost = "${node}.elwert.dev";
      targetUser = "root";
    };

    nixpkgs.system = self.nixosConfigurations.${node}.config.nixpkgs.system;
    imports = self.nixosConfigurations.${node}._module.args.modules;
  };

In particular the self.nixosConfigurations.${node}._module.args.modules line

In reply to @belak:matrix.org

Is there a good way to convert from a flake's nixosConfigurations output to a colemena node? At the moment, I'm using this, but it seems fairly hacky:

  mkColmenaNode = node: {
    deployment = {
      targetHost = "${node}.elwert.dev";
      targetUser = "root";
    };

    nixpkgs.system = self.nixosConfigurations.${node}.config.nixpkgs.system;
    imports = self.nixosConfigurations.${node}._module.args.modules;
  };

In particular the self.nixosConfigurations.${node}._module.args.modules line

In reply to @me:indeednotjames.com
you can also specify colmena as a flake input and pass your colmenaHive attrset to nixosConfiguration, one sec

In reply to @sammy:cherrykitten.dev
see here and the following mesaages after