Add an option to prefer upstream Nix, implementing ItS#3 part one (#1664)

* Add an option to prefer upstream Nix, implementing ItS#3 part one

Ref: https://determinate.systems/blog/installer-dropping-upstream/

* Make determinate-nixd non-optional to simplify the prefer-upstream flag

* Clean up the messaging, notify users about upstream support going away

* Fixup docs generation (thank you coderabbit.)

Author: grahamc

Cargo.toml

@@ -9,8 +9,7 @@ repository = "https://github.com/DeterminateSystems/nix-installer"
 documentation = "https://docs.rs/nix-installer/latest/nix_installer"
 
 [features]
-default = ["cli", "diagnostics", "determinate-nix"]
-determinate-nix = []
+default = ["cli", "diagnostics"]
 cli = ["eyre", "color-eyre", "clap", "tracing-subscriber", "tracing-error"]
 diagnostics = ["detsys-ids-client", "is_ci"]
 
@@ -73,6 +72,6 @@ lto = true
 # available in docs.rs's build. It doesn't influence docs, so it's fine to set it to a bogus (but
 # existing-file) value.
 cargo-args = [
-    "--config", "env.NIX_INSTALLER_TARBALL_PATH=\"../Cargo.toml\"",
+    "--config", "env.DETERMINATE_NIX_TARBALL_PATH=\"../Cargo.toml\"",
     "--config", "env.DETERMINATE_NIXD_BINARY_PATH=\"../Cargo.toml\""
 ]

src/action/common/provision_determinate_nixd.rs

@@ -23,14 +23,9 @@ pub struct ProvisionDeterminateNixd {
 impl ProvisionDeterminateNixd {
     #[tracing::instrument(level = "debug", skip_all)]
     pub async fn plan() -> Result<StatefulAction<Self>, ActionError> {
-        crate::distribution::DETERMINATE_NIXD_BINARY
-            .ok_or_else(|| Self::error(ActionErrorKind::DeterminateNixUnavailable))?;
-
-        let this = Self {
+        Ok(StatefulAction::uncompleted(Self {
             binary_location: DETERMINATE_NIXD_BINARY_PATH.into(),
-        };
-
-        Ok(StatefulAction::uncompleted(this))
+        }))
     }
 }
 
@@ -61,8 +56,7 @@ impl Action for ProvisionDeterminateNixd {
 
     #[tracing::instrument(level = "debug", skip_all)]
     async fn execute(&mut self) -> Result<(), ActionError> {
-        let bytes = crate::distribution::DETERMINATE_NIXD_BINARY
-            .ok_or_else(|| Self::error(ActionErrorKind::DeterminateNixUnavailable))?;
+        let bytes = crate::distribution::DETERMINATE_NIXD_BINARY;
 
         crate::util::remove_file(&self.binary_location, OnMissing::Ignore)
             .await

src/cli/subcommand/install/determinate.rs

@@ -11,11 +11,14 @@ const PRE_PKG_SUGGEST: &str = "For a more robust Nix installation, use the Deter
 const INSTALL_DETERMINATE_NIX_PROMPT: &str = "\
 Install Determinate Nix?
 
-Selecting 'no' will install Nix from NixOS.org, without automated garbage collection and enterprise certificate support.\
+It has stable flakes, lazy trees, parallel evaluation, and more.
+
+Selecting 'no' will install upstream Nix, which comes from NixOS.org.\
 ";
 
 const DETERMINATE_MSG_EXPLAINER: &str = "\
 Determinate Nix is Determinate Systems' validated and secure downstream Nix distribution for enterprises. \
+It is the direct result of our work to ship meaningful user experience and reliability improvements to Nix.
 It comes bundled with Determinate Nixd, a helpful daemon that automates some otherwise-unpleasant aspects of using Nix, such as garbage collection, and enables you to easily authenticate with FlakeHub.
 
 For more details: https://dtr.mn/determinate-nix\
@@ -41,7 +44,51 @@ pub(crate) async fn prompt_for_determinate<T: Feedback>(
 ) -> eyre::Result<Option<String>> {
     let planner_settings = planner.common_settings_mut();
 
-    if !planner_settings.determinate_nix && std::io::stdin().is_terminal() && !no_confirm {
+    if !planner_settings.determinate_nix {
+        // This is deliberately checking the determinate_nix option, and not `.distribution()`.
+        // When we default to Determinate Nix on November 10, we'll change prefer_upstream's default to false.
+        // Then, .distribution() will be Determinate Nix, but .determinate_nix will still be false.
+        // That means we'll still show this warning.
+
+        eprintln!();
+        eprintln!(
+            "{} The Determinate Nix Installer will stop distributing upstream Nix no sooner than {}.",
+            "Important:".bold().red().italic(),
+            "January 1, 2026".italic()
+        );
+
+        eprintln!("\n{}", "Timeline".bold().underline());
+
+        eprintln!(
+            "* {}: we are changing the installer to default to Determinate Nix.",
+            "November 10".bold()
+        );
+        eprintln!(
+            "  You can add the `{}` flag now to keep upstream Nix as the default.",
+            "--prefer-upstream-nix".italic()
+        );
+        eprintln!(
+            "* {}: we are removing support for installing upstream Nix.",
+            "January 1".bold()
+        );
+        eprintln!(
+            "  The `{}` flag will not have an effect any longer.",
+            "--prefer-upstream-nix".italic()
+        );
+
+        eprintln!(
+            "\nThe DeterminateSystems/nix-installer-action GitHub Action is also affected.\n"
+        );
+        eprintln!(
+            "{} https://determinate.systems/blog/installer-dropping-upstream/",
+            "Details:".bold().italic()
+        );
+    }
+
+    if planner_settings.distribution().is_upstream()
+        && std::io::stdin().is_terminal()
+        && !no_confirm
+    {
         let base_prompt = feedback
             .get_feature_ptr_payload::<String>("dni-det-msg-interactive-prompt-ptr")
             .await
@@ -86,7 +133,7 @@ pub(crate) async fn prompt_for_determinate<T: Feedback>(
     }
 
     let post_install_message_feature = match (
-        planner_settings.determinate_nix,
+        planner_settings.distribution().is_determinate(),
         std::io::stdin().is_terminal() && !no_confirm,
     ) {
         (true, true) => Some("dni-post-det-int-ptr"),

src/diagnostics.rs

@@ -219,23 +219,24 @@ impl crate::feedback::Feedback for DiagnosticData {
             .set_fact("planner", planner.typetag_name().into())
             .await;
 
+        self.ids_client
+            .set_fact(
+                "install_determinate_nix",
+                planner
+                    .common_settings()
+                    .distribution()
+                    .is_determinate()
+                    .into(),
+            )
+            .await;
+
         if let Ok(ref settings) = planner.configured_settings().await {
             self.ids_client
                 .set_fact(
                     "configured_settings",
                     settings.keys().cloned().collect::<Vec<_>>().into(),
                 )
                 .await;
-
-            self.ids_client
-                .set_fact(
-                    "install_determinate_nix",
-                    settings
-                        .get("determinate_nix")
-                        .cloned()
-                        .unwrap_or(serde_json::Value::Bool(false)),
-                )
-                .await;
         }
 
         Ok(())

src/distribution.rs

@@ -9,6 +9,13 @@ pub enum Distribution {
 }
 
 impl Distribution {
+    pub fn is_determinate(&self) -> bool {
+        self == &Self::DeterminateNix
+    }
+    pub fn is_upstream(&self) -> bool {
+        self == &Self::Nix
+    }
+
     pub fn tarball_location_or(&self, user_preference: &Option<UrlOrPath>) -> TarballLocation {
         if let Some(pref) = user_preference {
             return TarballLocation::UrlOrPath(pref.clone());
@@ -24,10 +31,7 @@ impl Distribution {
                     .expect("Fault: the built-in Nix tarball URL does not parse."),
             ),
             Distribution::DeterminateNix => {
-                TarballLocation::InMemory(
-                    DETERMINATE_NIX_TARBALL_PATH.expect("Fault: this build of Determinate Nix Installer is not equipped to install Determinate Nix."),
-                    DETERMINATE_NIX_TARBALL.expect("Fault: this build of Determinate Nix Installer is not equipped to install Determinate Nix.")
-                )
+                TarballLocation::InMemory(DETERMINATE_NIX_TARBALL_PATH, DETERMINATE_NIX_TARBALL)
             },
         }
     }
@@ -40,25 +44,13 @@ pub enum TarballLocation {
 
 pub const NIX_TARBALL_URL: &str = env!("NIX_TARBALL_URL");
 
-#[cfg(feature = "determinate-nix")]
-pub const DETERMINATE_NIX_TARBALL_PATH: Option<&str> = Some(env!("DETERMINATE_NIX_TARBALL_PATH"));
-#[cfg(feature = "determinate-nix")]
+pub const DETERMINATE_NIX_TARBALL_PATH: &str = env!("DETERMINATE_NIX_TARBALL_PATH");
 /// The DETERMINATE_NIX_TARBALL environment variable should point to a target-appropriate
 /// Determinate Nix installation tarball, like determinate-nix-2.21.2-aarch64-darwin.tar.xz.
 /// The contents are embedded in the resulting binary.
-pub const DETERMINATE_NIX_TARBALL: Option<&[u8]> =
-    Some(include_bytes!(env!("DETERMINATE_NIX_TARBALL_PATH")));
+pub const DETERMINATE_NIX_TARBALL: &[u8] = include_bytes!(env!("DETERMINATE_NIX_TARBALL_PATH"));
 
-#[cfg(feature = "determinate-nix")]
 /// The DETERMINATE_NIXD_BINARY_PATH environment variable should point to a target-appropriate
 /// static build of the Determinate Nixd binary. The contents are embedded in the resulting
-/// binary if the determinate-nix feature is turned on.
-pub const DETERMINATE_NIXD_BINARY: Option<&[u8]> =
-    Some(include_bytes!(env!("DETERMINATE_NIXD_BINARY_PATH")));
-
-#[cfg(not(feature = "determinate-nix"))]
-pub const DETERMINATE_NIXD_BINARY: Option<&[u8]> = None;
-#[cfg(not(feature = "determinate-nix"))]
-pub const DETERMINATE_NIX_TARBALL: Option<&[u8]> = None;
-#[cfg(not(feature = "determinate-nix"))]
-pub const DETERMINATE_NIX_TARBALL_PATH: Option<&str> = None;
+/// binary.
+pub const DETERMINATE_NIXD_BINARY: &[u8] = include_bytes!(env!("DETERMINATE_NIXD_BINARY_PATH"));

src/planner/mod.rs

@@ -226,6 +226,15 @@ impl BuiltinPlanner {
         Ok(built)
     }
 
+    pub fn common_settings(&self) -> &CommonSettings {
+        match self {
+            BuiltinPlanner::Linux(inner) => &inner.settings,
+            BuiltinPlanner::SteamDeck(inner) => &inner.settings,
+            BuiltinPlanner::Ostree(inner) => &inner.settings,
+            BuiltinPlanner::Macos(inner) => &inner.settings,
+        }
+    }
+
     pub fn common_settings_mut(&mut self) -> &mut CommonSettings {
         match self {
             BuiltinPlanner::Linux(inner) => &mut inner.settings,

src/settings.rs

@@ -53,6 +53,18 @@ pub struct CommonSettings {
     )]
     pub determinate_nix: bool,
 
+    /// Prefer installing upstream Nix if possible when run in an automated context.
+    #[cfg_attr(
+        feature = "cli",
+        clap(
+            long = "prefer-upstream-nix",
+            env = "NIX_INSTALLER_PREFER_UPSTREAM_NIX",
+            // Note this default is replicated in a default() implementation
+            default_value = "true"
+        )
+    )]
+    pub prefer_upstream: bool,
+
     /// Modify the user profile to automatically load Nix
     #[cfg_attr(
         feature = "cli",
@@ -228,6 +240,7 @@ impl CommonSettings {
 
         Ok(Self {
             determinate_nix: false,
+            prefer_upstream: true,
             modify_profile: true,
             nix_build_group_name: String::from(crate::settings::DEFAULT_NIX_BUILD_USER_GROUP_NAME),
             nix_build_group_id: default_nix_build_group_id(),
@@ -247,6 +260,7 @@ impl CommonSettings {
     pub fn settings(&self) -> Result<HashMap<String, serde_json::Value>, InstallSettingsError> {
         let Self {
             determinate_nix,
+            prefer_upstream,
             modify_profile,
             nix_build_group_name,
             nix_build_group_id,
@@ -266,6 +280,10 @@ impl CommonSettings {
             "determinate_nix".into(),
             serde_json::to_value(determinate_nix)?,
         );
+        map.insert(
+            "prefer_upstream".into(),
+            serde_json::to_value(prefer_upstream)?,
+        );
         map.insert(
             "modify_profile".into(),
             serde_json::to_value(modify_profile)?,
@@ -306,8 +324,11 @@ impl CommonSettings {
     pub fn distribution(&self) -> Distribution {
         if self.determinate_nix {
             Distribution::DeterminateNix
-        } else {
+        } else if self.prefer_upstream {
+            // If the user passed --prefer-upstream (or it defaults to true), default back to Nix
             Distribution::Nix
+        } else {
+            Distribution::DeterminateNix
         }
     }
 }

tests/fixtures/linux/linux.json

@@ -1145,6 +1145,7 @@
     "planner": "linux",
     "settings": {
       "determinate_nix": false,
+      "prefer_upstream": true,
       "modify_profile": true,
       "nix_build_group_name": "nixbld",
       "nix_build_group_id": 30000,

tests/fixtures/linux/steam-deck.json

@@ -1173,6 +1173,7 @@
     "persistence": "/home/nix",
     "settings": {
       "determinate_nix": false,
+      "prefer_upstream": true,
       "modify_profile": true,
       "nix_build_group_name": "nixbld",
       "nix_build_group_id": 30000,

tests/fixtures/macos/macos.json

@@ -1245,6 +1245,7 @@
     "planner": "macos",
     "settings": {
       "determinate_nix": false,
+      "prefer_upstream": true,
       "modify_profile": true,
       "nix_build_group_name": "nixbld",
       "nix_build_group_id": 350,