Disable auto-allocate-uids on Linux too (#638)

* Disable auto-allocate-uids on Linux too

* Fix clippy/fmt

README.md

@@ -418,11 +418,10 @@ curl -sSf -L https://github.com/DeterminateSystems/nix-installer/releases/downlo
 Differing from the upstream [Nix](https://github.com/NixOS/nix) installer scripts:
 
 * In `nix.conf`:
-  + the `auto-allocate-uids`, `nix-command` and `flakes` features are enabled
+  + the `nix-command` and `flakes` features are enabled
   + `bash-prompt-prefix` is set
   + `auto-optimise-store` is set to `true` (On Linux only)
   * `extra-nix-path` is set to `nixpkgs=flake:nixpkgs`
-  * `auto-allocate-uids` is set to `true`.  (On Linux only)
 * an installation receipt (for uninstalling) is stored at `/nix/receipt.json` as well as a copy of the install binary at `/nix/nix-installer`
 * `nix-channel --update` is not run, `~/.nix-channels` is not provisioned
 * `NIX_SSL_CERT_FILE` is set in the various shell profiles if the `ssl-cert-file` argument is used.

src/action/common/place_nix_configuration.rs

@@ -95,10 +95,7 @@ impl PlaceNixConfiguration {
 
         let mut defaults_conf_settings = vec![
             ("build-users-group", nix_build_group_name),
-            (
-                "experimental-features",
-                "nix-command flakes auto-allocate-uids".into(),
-            ),
+            ("experimental-features", "nix-command flakes".into()),
         ];
 
         defaults_conf_settings.push(("bash-prompt-prefix", "(nix:$name)\\040".into()));
@@ -116,10 +113,6 @@ impl PlaceNixConfiguration {
         // https://github.com/DeterminateSystems/nix-installer/issues/449#issuecomment-1551782281
         #[cfg(not(target_os = "macos"))]
         defaults_conf_settings.push(("auto-optimise-store", "true".into()));
-        // Auto-allocate uids is broken on Mac. Tools like `whoami` don't work.
-        // e.g. https://github.com/NixOS/nix/issues/8444
-        #[cfg(not(target_os = "macos"))]
-        defaults_conf_settings.push(("auto-allocate-uids", "true".into()));
         let defaults_conf_insert_fragment = defaults_conf_settings
             .iter()
             .map(|(s, v)| format!("{s} = {v}"))
@@ -204,9 +197,7 @@ impl PlaceNixConfiguration {
             );
 
             // Some settings (eg `experimental-features`) we must be able to set it.
-            let mut required_settings = vec!["experimental-features"];
-            #[cfg(not(target_os = "macos"))]
-            required_settings.push("auto-allocate-uids");
+            let required_settings = vec!["experimental-features"];
             for required_setting in required_settings {
                 if let Some((existing_setting, existing_value)) = existing_conf_settings
                     .iter()

src/settings.rs

@@ -113,10 +113,6 @@ pub struct CommonSettings {
     pub nix_build_user_prefix: String,
 
     /// Number of build users to create
-    #[cfg_attr(
-        all(target_os = "linux", feature = "cli"),
-        doc = "On Linux, Nix's `auto-allocate-uids` feature will be enabled, so users don't need to be created."
-    )]
     #[cfg_attr(
         feature = "cli",
         clap(
@@ -127,7 +123,7 @@ pub struct CommonSettings {
         )
     )]
     #[cfg_attr(all(target_os = "macos", feature = "cli"), clap(default_value = "32"))]
-    #[cfg_attr(all(target_os = "linux", feature = "cli"), clap(default_value = "0"))]
+    #[cfg_attr(all(target_os = "linux", feature = "cli"), clap(default_value = "32"))]
     pub nix_build_user_count: u32,
 
     /// The Nix build user base UID (ascending)