Merge pull request #155892 from hercules-ci/nixos-etc-unit-test

nixos: Refactor to allow `etc` unit test

3 files changed, 85 insertions, 3 deletions

diff --git a/nixos/modules/system/etc/etc-activation.nix b/nixos/modules/system/etc/etc-activation.nix
new file mode 100644
index 00000000000..78010495018
--- /dev/null
+++ b/nixos/modules/system/etc/etc-activation.nix
@@ -0,0 +1,12 @@
+{ config, lib, ... }:
+let
+  inherit (lib) stringAfter;
+in {
+
+  imports = [ ./etc.nix ];
+
+  config = {
+    system.activationScripts.etc =
+      stringAfter [ "users" "groups" ] config.system.build.etcActivationCommands;
+  };
+}
diff --git a/nixos/modules/system/etc/etc.nix b/nixos/modules/system/etc/etc.nix
index 6cc8c341e6d..ed552fecec5 100644
--- a/nixos/modules/system/etc/etc.nix
+++ b/nixos/modules/system/etc/etc.nix
@@ -66,6 +66,8 @@ in
 
 {
 
+  imports = [ ../build.nix ];
+
   ###### interface
 
   options = {
@@ -188,14 +190,12 @@ in
   config = {
 
     system.build.etc = etc;
-
-    system.activationScripts.etc = stringAfter [ "users" "groups" ]
+    system.build.etcActivationCommands =
       ''
         # Set up the statically computed bits of /etc.
         echo "setting up /etc..."
         ${pkgs.perl.withPackages (p: [ p.FileSlurp ])}/bin/perl ${./setup-etc.pl} ${etc}/etc
       '';
-
   };
 
 }
diff --git a/nixos/modules/system/etc/test.nix b/nixos/modules/system/etc/test.nix
new file mode 100644
index 00000000000..5e43b155038
--- /dev/null
+++ b/nixos/modules/system/etc/test.nix
@@ -0,0 +1,70 @@
+{ lib
+, coreutils
+, fakechroot
+, fakeroot
+, evalMinimalConfig
+, pkgsModule
+, runCommand
+, util-linux
+, vmTools
+, writeText
+}:
+let
+  node = evalMinimalConfig ({ config, ... }: {
+    imports = [ pkgsModule ../etc/etc.nix ];
+    environment.etc."passwd" = {
+      text = passwdText;
+    };
+    environment.etc."hosts" = {
+      text = hostsText;
+      mode = "0751";
+    };
+  });
+  passwdText = ''
+    root:x:0:0:System administrator:/root:/run/current-system/sw/bin/bash
+  '';
+  hostsText = ''
+    127.0.0.1 localhost
+    ::1 localhost
+    # testing...
+  '';
+in
+lib.recurseIntoAttrs {
+  test-etc-vm =
+    vmTools.runInLinuxVM (runCommand "test-etc-vm" { } ''
+      mkdir -p /etc
+      ${node.config.system.build.etcActivationCommands}
+      set -x
+      [[ -L /etc/passwd ]]
+      diff /etc/passwd ${writeText "expected-passwd" passwdText}
+      [[ 751 = $(stat --format %a /etc/hosts) ]]
+      diff /etc/hosts ${writeText "expected-hosts" hostsText}
+      set +x
+      touch $out
+    '');
+
+  # fakeroot is behaving weird
+  test-etc-fakeroot =
+    runCommand "test-etc"
+      {
+        nativeBuildInputs = [
+          fakeroot
+          fakechroot
+          # for chroot
+          coreutils
+          # fakechroot needs getopt, which is provided by util-linux
+          util-linux
+        ];
+        fakeRootCommands = ''
+          mkdir -p /etc
+          ${node.config.system.build.etcActivationCommands}
+          diff /etc/hosts ${writeText "expected-hosts" hostsText}
+          touch $out
+        '';
+      } ''
+      mkdir fake-root
+      export FAKECHROOT_EXCLUDE_PATH=/dev:/proc:/sys:${builtins.storeDir}:$out
+      fakechroot fakeroot chroot $PWD/fake-root bash -c 'source $stdenv/setup; eval "$fakeRootCommands"'
+    '';
+
+}