NixOS Live Image: convert to a flake

Now `nixpkgs` will be pointing to a specific release, which has a much
smaller chance to unexpectedly break. Currently 23.11. The next one will
be 24.05, 24.11, etc.

NixOS *releases* receive security updates, but packages are upgraded
conservatively, thus don't generally break. As a result, we should need
to worry about NixOS upgrades every 6-12 months. The upgrade means "bump
the version number and try to build it". If it breaks, it will generally
break only then. Less reactive, more proactive surprises.

`flake.nix` was written by @thomaseizinger in
https://github.com/drduh/YubiKey-Guide/issues/406. Changes from the
original:
- change Gnome to xfce. Now it loads with 384MB of RAM and works well
  with the simplest graphics (hello qemu).
- less nasty workaround for hopenpgp-tools. Fixed upstream
  (https://github.com/NixOS/nixpkgs/pull/279117).
- do not default `copytoram`, user can select this option in the
  bootloader.

Here is how to test it:

```
$ nix run .#nixosConfigurations.yubikeyLive.x86_64-linux.config.system.build.vm
```

*Note for the maintainer*: it would be great if you could occasionally
run `nix flake update --commit-lock-file`, *especially* after updating
github.com/drduh/config.git.

Fixes #406

Co-authored-by: Thomas Eizinger <thomas@eizinger.io>

1 files changed, 44 insertions, 0 deletions

diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..bf452f1
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,44 @@
+{
+  "nodes": {
+    "drduhConfig": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1697417581,
+        "narHash": "sha256-R45L/Xv3z0lJhGt781wDbjaq1qc+sGTmsUt+XHwgf4A=",
+        "owner": "drduh",
+        "repo": "config",
+        "rev": "8c21617100795fea2313656abdf25f93b98fdc30",
+        "type": "github"
+      },
+      "original": {
+        "owner": "drduh",
+        "repo": "config",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1706826059,
+        "narHash": "sha256-N69Oab+cbt3flLvYv8fYnEHlBsWwdKciNZHUbynVEOA=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "25e3d4c0d3591c99929b1ec07883177f6ea70c9d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-23.11",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "drduhConfig": "drduhConfig",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}