feat(agent): system info collector for pveversion/zfs/apt

agent/lib/proxmox_agent/collectors/system_info.ex

@@ -0,0 +1,45 @@
+defmodule ProxmoxAgent.Collectors.SystemInfo do
+  @moduledoc "Slow-path system metadata: pveversion, zfs version, apt upgradable count."
+
+  @spec collect(keyword()) :: %{
+          pve_version: String.t() | nil,
+          zfs_version: String.t() | nil,
+          pending_updates: non_neg_integer(),
+          agent_version: String.t(),
+          errors: [map()]
+        }
+  def collect(opts \\ []) do
+    runner = Keyword.get(opts, :runner, &ProxmoxAgent.Shell.run/2)
+
+    {pve, e1} = trim_output(runner.("pveversion", []), :pveversion)
+    {zfs, e2} = trim_output(runner.("zfs", ["--version"]), :zfs_version)
+    {apt, e3} = runner.("apt", ["list", "--upgradable"]) |> count_upgrades()
+
+    %{
+      pve_version: pve,
+      zfs_version: zfs,
+      pending_updates: apt,
+      agent_version: ProxmoxAgent.version(),
+      errors: Enum.filter([e1, e2, e3], & &1)
+    }
+  end
+
+  defp trim_output({:ok, text}, _tag), do: {String.trim(text) |> first_line(), nil}
+
+  defp trim_output({:error, reason}, tag),
+    do: {nil, %{tag: Atom.to_string(tag), message: inspect(reason)}}
+
+  defp first_line(str), do: str |> String.split("\n", parts: 2) |> hd()
+
+  defp count_upgrades({:ok, text}) do
+    count =
+      text
+      |> String.split("\n", trim: true)
+      |> Enum.count(&String.contains?(&1, "[upgradable"))
+
+    {count, nil}
+  end
+
+  defp count_upgrades({:error, reason}),
+    do: {0, %{tag: "apt_upgradable", message: inspect(reason)}}
+end