From 17be62f56cce92fb6c38d9ba3e8535b37e3b75a1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Domen=20Ko=C5=BEar?= <domen@dev.si>
Date: Sat, 22 Jun 2019 20:10:03 +0200
Subject: [PATCH] Add configurationLimit to systemd-boot to prevent running out
 of disk space
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Refs #23926

(cherry picked from commit 224a6562a4880195afa5c184e755b8ecaba41536)
Signed-off-by: Domen Kožar <domen@dev.si>
---
 .../loader/systemd-boot/systemd-boot-builder.py   |  4 +++-
 .../boot/loader/systemd-boot/systemd-boot.nix     | 15 +++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/nixos/modules/system/boot/loader/systemd-boot/systemd-boot-builder.py b/nixos/modules/system/boot/loader/systemd-boot/systemd-boot-builder.py
index 6016a85ea061..5d91b6d5c1a0 100644
--- a/nixos/modules/system/boot/loader/systemd-boot/systemd-boot-builder.py
+++ b/nixos/modules/system/boot/loader/systemd-boot/systemd-boot-builder.py
@@ -124,7 +124,9 @@ def get_generations(profile=None):
         universal_newlines=True)
     gen_lines = gen_list.split('\n')
     gen_lines.pop()
-    return [ (profile, int(line.split()[0])) for line in gen_lines ]
+
+    configurationLimit = @configurationLimit@
+    return [ (profile, int(line.split()[0])) for line in gen_lines ][-configurationLimit:]
 
 def remove_old_entries(gens):
     rex_profile = re.compile("^@efiSysMountPoint@/loader/entries/nixos-(.*)-generation-.*\.conf$")
diff --git a/nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix b/nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix
index 9ad2a2779e18..670f2a0bac3f 100644
--- a/nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix
+++ b/nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix
@@ -22,6 +22,8 @@ let
 
     editor = if cfg.editor then "True" else "False";
 
+    configurationLimit = if cfg.configurationLimit == null then 0 else cfg.configurationLimit;
+
     inherit (cfg) consoleMode;
 
     inherit (efi) efiSysMountPoint canTouchEfiVariables;
@@ -55,6 +57,19 @@ in {
       '';
     };
 
+    configurationLimit = mkOption {
+      default = null;
+      example = 120;
+      type = types.nullOr types.int;
+      description = ''
+        Maximum number of latest generations in the boot menu. 
+        Useful to prevent boot partition running out of disk space.
+
+        <literal>null</literal> means no limit i.e. all generations 
+        that were not garbage collected yet.
+      '';
+    };
+
     consoleMode = mkOption {
       default = "keep";