Merge pull request 'clan machines generations' (#4848) from Qubasa/clan-core:add_generate_cli into main

Reviewed-on: https://git.clan.lol/clan/clan-core/pulls/4848

pkgs/clan-cli/clan_lib/machines/generations.py

@@ -0,0 +1,44 @@
+import json
+from dataclasses import dataclass, field
+
+from clan_lib.api import API
+from clan_lib.ssh.localhost import LocalHost
+from clan_lib.ssh.remote import Remote
+
+
+@dataclass(order=True, frozen=True)
+class MachineGeneration:
+    generation: int
+    date: str
+    nixos_version: str
+    kernel_version: str
+    configuration_revision: str
+    specialisations: list[str] = field(default_factory=list)
+    current: bool = False
+
+
+@API.register
+def get_machine_generations(target_host: Remote | LocalHost) -> list[MachineGeneration]:
+    """Get the nix generations installed on the target host and compare them with the machine."""
+    with target_host.host_connection() as target_host_conn:
+        cmd = [
+            "nixos-rebuild",
+            "list-generations",
+            "--json",
+        ]
+        res = target_host_conn.run(cmd)
+
+        data = json.loads(res.stdout.strip())
+        sorted_data = sorted(data, key=lambda gen: gen.get("generation", 0))
+        return [
+            MachineGeneration(
+                generation=gen.get("generation"),
+                date=gen.get("date"),
+                nixos_version=gen.get("nixosVersion", ""),
+                kernel_version=gen.get("kernelVersion", ""),
+                configuration_revision=gen.get("configurationRevision", ""),
+                specialisations=gen.get("specialisations", []),
+                current=gen.get("current", False),
+            )
+            for gen in sorted_data
+        ]