From 8a6c78361625975de529f50e8e7e24798209a5fb Mon Sep 17 00:00:00 2001
From: Daiderd Jordan <daiderd@gmail.com>
Date: Wed, 2 Jan 2019 21:13:45 +0100
Subject: [PATCH] checks: generalize and make them more configurable

All the checks are now aggregated in system.checks.text making it easy
to allow certain checks to be disabled as well as disabling them
alltogether if desired. eg.

    # Disable all checks.
    system.checks.text = mkForce "";

Fixes #117
---
 modules/system/checks.nix | 37 +++++++++++++++++++++++++++----------
 1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/modules/system/checks.nix b/modules/system/checks.nix
index 9a3bdfc..af6cb6f 100644
--- a/modules/system/checks.nix
+++ b/modules/system/checks.nix
@@ -3,6 +3,8 @@
 with lib;
 
 let
+  cfg = config.system.checks;
+
   darwinChanges = ''
     darwinChanges=/dev/null
     if test -e /run/current-system/darwin-changes; then
@@ -30,7 +32,7 @@ let
     fi
   '';
 
-  buildUsers = optionalString config.services.nix-daemon.enable ''
+  buildUsers = ''
     buildUser=$(dscl . -read /Groups/nixbld GroupMembership 2>&1 | awk '/^GroupMembership: / {print $2}') || true
     if [ -z $buildUser ]; then
         echo "error: Using the nix-daemon requires build users, aborting activation" >&2
@@ -135,7 +137,7 @@ let
     fi
   '';
 
-  nixGarbageCollector = optionalString config.nix.gc.automatic ''
+  nixGarbageCollector = ''
     if test -O /nix/store; then
         echo "error: A single-user install can't run gc as root, aborting activation" >&2
         echo "Configure the garbage collector to run as the current user:" >&2
@@ -149,19 +151,34 @@ in
 
 {
   options = {
+    system.checks.verifyNixPath = mkOption {
+      type = types.bool;
+      default = true;
+      description = "Whether to run the NIX_PATH validation checks.";
+    };
+
+    system.checks.text = mkOption {
+      internal = true;
+      type = types.lines;
+      default = "";
+    };
   };
 
   config = {
 
+    system.checks.text = mkMerge [
+      darwinChanges
+      runLink
+      (mkIf config.services.nix-daemon.enable buildUsers)
+      nixStore
+      (mkIf config.nix.gc.automatic nixGarbageCollector)
+      nixChannels
+      nixInstaller
+      (mkIf cfg.verifyNixPath nixPath)
+    ];
+
     system.activationScripts.checks.text = ''
-      ${darwinChanges}
-      ${runLink}
-      ${buildUsers}
-      ${nixStore}
-      ${nixGarbageCollector}
-      ${nixChannels}
-      ${nixInstaller}
-      ${nixPath}
+      ${cfg.text}
 
       if test ''${checkActivation:-0} -eq 1; then
         echo "ok" >&2