nixos/nix-channel.nix: shellcheck and fix the activation checkorigin/backport-323613-to-release-24.05

(cherry picked from commit 2d9a6864833e3cca4b05aa6bd4ef88c8813989ca)

4 files changed, 42 insertions, 21 deletions

diff --git a/nixos/modules/config/nix-channel.nix b/nixos/modules/config/nix-channel.nix
index 5cd7095c85b5..ff8eca01cac8 100644
--- a/nixos/modules/config/nix-channel.nix
+++ b/nixos/modules/config/nix-channel.nix
@@ -100,26 +100,6 @@ in
     ];
 
     system.activationScripts.no-nix-channel = mkIf (!cfg.channel.enable)
-      (stringAfter [ "etc" "users" ] ''
-        explainChannelWarning=0
-        if [ -e "/root/.nix-defexpr/channels" ]; then
-            warn '/root/.nix-defexpr/channels exists, but channels have been disabled.'
-            explainChannelWarning=1
-        fi
-        if [ -e "/nix/var/nix/profiles/per-user/root/channels" ]; then
-            warn "/nix/var/nix/profiles/per-user/root/channels exists, but channels have been disabled."
-            explainChannelWarning=1
-        fi
-        getent passwd | while IFS=: read -r _ _ _ _ _ home _ ; do
-            if [ -n  "$home" -a -e "$home/.nix-defexpr/channels" ]; then
-                warn "$home/.nix-defexpr/channels exists, but channels have been disabled." 1>&2
-                explainChannelWarning=1
-            fi
-        done
-        if [ $explainChannelWarning -eq 1 ]; then
-            echo "Due to https://github.com/NixOS/nix/issues/9574, Nix may still use these channels when NIX_PATH is unset." 1>&2
-            echo "Delete the above directory or directories to prevent this." 1>&2
-        fi
-      '');
+      (stringAfter [ "etc" "users" ] (builtins.readFile ./nix-channel/activation-check.sh));
   };
 }
diff --git a/nixos/modules/config/nix-channel/activation-check.sh b/nixos/modules/config/nix-channel/activation-check.sh
new file mode 100644
index 000000000000..42b1b712d702
--- /dev/null
+++ b/nixos/modules/config/nix-channel/activation-check.sh
@@ -0,0 +1,21 @@
+# shellcheck shell=bash
+
+explainChannelWarning=0
+if [[ -e "/root/.nix-defexpr/channels" ]]; then
+    warn '/root/.nix-defexpr/channels exists, but channels have been disabled.'
+    explainChannelWarning=1
+fi
+if [[ -e "/nix/var/nix/profiles/per-user/root/channels" ]]; then
+    warn "/nix/var/nix/profiles/per-user/root/channels exists, but channels have been disabled."
+    explainChannelWarning=1
+fi
+while IFS=: read -r _ _ _ _ _ home _ ; do
+    if [[ -n  "$home" && -e "$home/.nix-defexpr/channels" ]]; then
+        warn "$home/.nix-defexpr/channels exists, but channels have been disabled." 1>&2
+        explainChannelWarning=1
+    fi
+done < <(getent passwd)
+if [[ $explainChannelWarning -eq 1 ]]; then
+    echo "Due to https://github.com/NixOS/nix/issues/9574, Nix may still use these channels when NIX_PATH is unset." 1>&2
+    echo "Delete the above directory or directories to prevent this." 1>&2
+fi
diff --git a/nixos/modules/config/nix-channel/test.nix b/nixos/modules/config/nix-channel/test.nix
new file mode 100644
index 000000000000..4b00cf9db3c4
--- /dev/null
+++ b/nixos/modules/config/nix-channel/test.nix
@@ -0,0 +1,19 @@
+# Run:
+#   nix-build -A nixosTests.nix-channel
+{ lib, testers }:
+let
+  inherit (lib) fileset;
+
+  runShellcheck = testers.shellcheck {
+    src = fileset.toSource {
+      root = ./.;
+      fileset = fileset.unions [
+        ./activation-check.sh
+      ];
+    };
+  };
+
+in
+lib.recurseIntoAttrs {
+  inherit runShellcheck;
+}
diff --git a/nixos/tests/all-tests.nix b/nixos/tests/all-tests.nix
index 624fb6813517..f544210485fd 100644
--- a/nixos/tests/all-tests.nix
+++ b/nixos/tests/all-tests.nix
@@ -607,6 +607,7 @@ in {
   nbd = handleTest ./nbd.nix {};
   ncdns = handleTest ./ncdns.nix {};
   ndppd = handleTest ./ndppd.nix {};
+  nix-channel = pkgs.callPackage ../modules/config/nix-channel/test.nix { };
   nebula = handleTest ./nebula.nix {};
   netbird = handleTest ./netbird.nix {};
   nimdow = handleTest ./nimdow.nix {};