Integrate nix-config-parser (#263)

Co-authored-by: Ana Hobden <operator@hoverbear.org>

Cargo.lock

@@ -932,6 +932,16 @@ dependencies = [
  "static_assertions",
 ]
 
+[[package]]
+name = "nix-config-parser"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cfd0a73a9c5f1f960f435be5ade7dd728d5039e6e92dbd5764f8c3d701491fc1"
+dependencies = [
+ "serde",
+ "thiserror",
+]
+
 [[package]]
 name = "nix-installer"
 version = "0.4.0"
@@ -947,6 +957,7 @@ dependencies = [
  "glob",
  "is_ci",
  "nix",
+ "nix-config-parser",
  "os-release",
  "owo-colors",
  "plist",

Cargo.toml

@@ -57,6 +57,7 @@ uuid = { version = "1.2.2", features = ["serde"] }
 os-release = { version = "0.1.0", default-features = false, optional = true }
 is_ci = { version = "1.1.1", default-features = false, optional = true }
 strum = { version = "0.24.1", features = ["derive"] }
+nix-config-parser = { version = "0.1.2", features = ["serde"] }
 
 [dev-dependencies]
 eyre = { version = "0.6.8", default-features = false, features = [ "track-caller" ] }

src/action/base/create_or_merge_nix_config.rs

@@ -0,0 +1,685 @@
+use std::{
+    os::unix::fs::PermissionsExt,
+    path::{Path, PathBuf},
+};
+
+use nix_config_parser::NixConfig;
+use rand::Rng;
+use tokio::{
+    fs::{remove_file, OpenOptions},
+    io::AsyncWriteExt,
+};
+use tracing::{span, Span};
+
+use crate::action::{Action, ActionDescription, ActionError, ActionTag, StatefulAction};
+
+/// The `nix.conf` configuration names that are safe to merge.
+// FIXME(@cole-h): make configurable by downstream users?
+const MERGEABLE_CONF_NAMES: &[&str] = &["experimental-features"];
+const NIX_CONF_MODE: u32 = 0o644;
+const NIX_CONF_COMMENT_CHAR: char = '#';
+
+#[non_exhaustive]
+#[derive(Debug, thiserror::Error)]
+pub enum CreateOrMergeNixConfigError {
+    #[error(transparent)]
+    ParseNixConfig(#[from] nix_config_parser::ParseError),
+    #[error("Could not merge Nix configuration for key(s) {}; consider removing them from `{1}` in your editor, or removing your existing configuration with `rm {1}`",
+        .0
+        .iter()
+        .map(|v| format!("`{v}`"))
+        .collect::<Vec<_>>()
+        .join(", "))]
+    UnmergeableConfig(Vec<String>, std::path::PathBuf),
+}
+
+/// Create or merge an existing `nix.conf` at the specified path.
+#[derive(Debug, serde::Deserialize, serde::Serialize, Clone)]
+pub struct CreateOrMergeNixConfig {
+    pub(crate) path: PathBuf,
+    pending_nix_config: NixConfig,
+}
+
+impl CreateOrMergeNixConfig {
+    #[tracing::instrument(level = "debug", skip_all)]
+    pub async fn plan(
+        path: impl AsRef<Path>,
+        pending_nix_config: NixConfig,
+    ) -> Result<StatefulAction<Self>, ActionError> {
+        let path = path.as_ref().to_path_buf();
+
+        let this = Self {
+            path,
+            pending_nix_config,
+        };
+
+        if this.path.exists() {
+            let (merged_nix_config, _) =
+                Self::validate_existing_nix_config(&this.pending_nix_config, &this.path)?;
+
+            if !merged_nix_config.settings().is_empty() {
+                return Ok(StatefulAction::uncompleted(this));
+            } else {
+                tracing::debug!(
+                    "Setting Nix configurations in `{}` already complete",
+                    this.path.display()
+                );
+                return Ok(StatefulAction::completed(this));
+            }
+        }
+
+        Ok(StatefulAction::uncompleted(this))
+    }
+
+    fn merge_pending_and_existing_nix_config(
+        pending_nix_config: &NixConfig,
+        existing_nix_config: &NixConfig,
+        path: &Path,
+    ) -> Result<(NixConfig, NixConfig), CreateOrMergeNixConfigError> {
+        let mut merged_nix_config = NixConfig::new();
+        let mut unmergeable_config_names = Vec::new();
+
+        for (pending_conf_name, pending_conf_value) in pending_nix_config.settings() {
+            if let Some(existing_conf_value) = existing_nix_config.settings().get(pending_conf_name)
+            {
+                let pending_conf_value = pending_conf_value.split(' ').collect::<Vec<_>>();
+                let existing_conf_value = existing_conf_value.split(' ').collect::<Vec<_>>();
+
+                if pending_conf_value
+                    .iter()
+                    .all(|e| existing_conf_value.contains(e))
+                {
+                    // If _all_ the values we want are present in the existing config,
+                    // merged_nix_config will be empty and this will be marked as completed. We
+                    // don't return early here because there may be more config options to
+                    // check.
+                } else if MERGEABLE_CONF_NAMES.contains(&pending_conf_name.as_str()) {
+                    let mut merged_conf_value =
+                        Vec::with_capacity(pending_conf_value.len() + existing_conf_value.len());
+                    merged_conf_value.extend(pending_conf_value);
+                    merged_conf_value.extend(existing_conf_value);
+                    merged_conf_value.dedup();
+                    let merged_conf_value = merged_conf_value.join(" ");
+                    let merged_conf_value = merged_conf_value.trim();
+
+                    merged_nix_config
+                        .settings_mut()
+                        .insert(pending_conf_name.to_owned(), merged_conf_value.to_owned());
+                } else {
+                    unmergeable_config_names.push(pending_conf_name.to_owned());
+                }
+            } else {
+                merged_nix_config
+                    .settings_mut()
+                    .insert(pending_conf_name.to_owned(), pending_conf_value.to_owned());
+            }
+        }
+
+        if !unmergeable_config_names.is_empty() {
+            return Err(CreateOrMergeNixConfigError::UnmergeableConfig(
+                unmergeable_config_names,
+                path.to_path_buf(),
+            ));
+        }
+
+        Ok((merged_nix_config, existing_nix_config.clone()))
+    }
+
+    fn validate_existing_nix_config(
+        pending_nix_config: &NixConfig,
+        path: &Path,
+    ) -> Result<(NixConfig, NixConfig), ActionError> {
+        let path = path.to_path_buf();
+        let metadata = path
+            .metadata()
+            .map_err(|e| ActionError::GettingMetadata(path.clone(), e))?;
+
+        if !metadata.is_file() {
+            return Err(ActionError::PathWasNotFile(path));
+        }
+
+        // Does the file have the right permissions?
+        let discovered_mode = metadata.permissions().mode();
+        // We only care about user-group-other permissions
+        let discovered_mode = discovered_mode & 0o777;
+
+        if discovered_mode != NIX_CONF_MODE {
+            return Err(ActionError::PathModeMismatch(
+                path,
+                discovered_mode,
+                NIX_CONF_MODE,
+            ));
+        }
+
+        let existing_nix_config = NixConfig::parse_file(&path)
+            .map_err(CreateOrMergeNixConfigError::ParseNixConfig)
+            .map_err(|e| ActionError::Custom(Box::new(e)))?;
+
+        let (merged_nix_config, existing_nix_config) = Self::merge_pending_and_existing_nix_config(
+            &pending_nix_config,
+            &existing_nix_config,
+            &path,
+        )
+        .map_err(|e| ActionError::Custom(Box::new(e)))?;
+
+        Ok((merged_nix_config, existing_nix_config))
+    }
+}
+
+#[async_trait::async_trait]
+#[typetag::serde(name = "create_or_merge_nix_config")]
+impl Action for CreateOrMergeNixConfig {
+    fn action_tag() -> ActionTag {
+        ActionTag("create_or_merge_nix_config")
+    }
+    fn tracing_synopsis(&self) -> String {
+        format!(
+            "Merge or create nix.conf file `{path}`",
+            path = self.path.display(),
+        )
+    }
+
+    fn tracing_span(&self) -> Span {
+        let span = span!(
+            tracing::Level::DEBUG,
+            "create_or_merge_nix_config",
+            path = tracing::field::display(self.path.display()),
+            mode = tracing::field::display(format!("{:#o}", NIX_CONF_MODE)),
+            pending_nix_config = tracing::field::Empty,
+        );
+
+        if tracing::enabled!(tracing::Level::TRACE) {
+            span.record(
+                "pending_nix_config",
+                &self
+                    .pending_nix_config
+                    .settings()
+                    .iter()
+                    .map(|(k, v)| format!("{k}=\"{v}\""))
+                    .collect::<Vec<_>>()
+                    .join(","),
+            );
+        }
+        span
+    }
+
+    fn execute_description(&self) -> Vec<ActionDescription> {
+        vec![ActionDescription::new(
+            self.tracing_synopsis(),
+            vec![format!(
+                "Added settings: {settings}",
+                settings = self
+                    .pending_nix_config
+                    .settings()
+                    .iter()
+                    .map(|(k, v)| format!("{k}=\"{v}\""))
+                    .collect::<Vec<_>>()
+                    .join(", "),
+            )],
+        )]
+    }
+
+    #[tracing::instrument(level = "debug", skip_all)]
+    async fn execute(&mut self) -> Result<(), ActionError> {
+        let Self {
+            path,
+            pending_nix_config,
+        } = self;
+
+        if tracing::enabled!(tracing::Level::TRACE) {
+            let span = tracing::Span::current();
+            span.record(
+                "pending_nix_config",
+                pending_nix_config
+                    .settings()
+                    .iter()
+                    .map(|(k, v)| format!("{k}='{v}'"))
+                    .collect::<Vec<_>>()
+                    .join(" "),
+            );
+        }
+
+        // Create a temporary file in the same directory as the one
+        // that the final file goes in, so that we can rename it
+        // atomically
+        let parent_dir = path.parent().expect("File must be in a directory");
+        let mut temp_file_path = parent_dir.to_owned();
+        {
+            let mut rng = rand::thread_rng();
+            temp_file_path.push(format!("nix-installer-tmp.{}", rng.gen::<u32>()));
+        }
+        let mut temp_file = OpenOptions::new()
+            .create(true)
+            .write(true)
+            // If the file is created, ensure that it has harmless
+            // permissions regardless of whether the mode will be
+            // changed later (if we ever create setuid executables,
+            // they should only become setuid once they are owned by
+            // the appropriate user)
+            .mode(0o600)
+            .open(&temp_file_path)
+            .await
+            .map_err(|e| {
+                ActionError::Open(temp_file_path.clone(), e)
+            })?;
+
+        let (mut merged_nix_config, mut existing_nix_config) = if path.exists() {
+            let (merged_nix_config, existing_nix_config) =
+                Self::validate_existing_nix_config(&pending_nix_config, &path)?;
+            (merged_nix_config, Some(existing_nix_config))
+        } else {
+            (pending_nix_config.clone(), None)
+        };
+
+        let mut new_config = String::new();
+
+        if let Some(existing_nix_config) = existing_nix_config.as_mut() {
+            let mut discovered_buf = tokio::fs::read_to_string(&path)
+                .await
+                .map_err(|e| ActionError::Read(path.to_path_buf(), e))?;
+
+            // We append a newline to ensure that, in the case there are comments at the end of the
+            // file and _NO_ trailing newline, we still preserve the entire block of comments.
+            discovered_buf.push('\n');
+
+            let (associated_lines, _, _) = discovered_buf.split('\n').fold(
+                (Vec::new(), Vec::new(), false),
+                |(mut all_assoc, mut current_assoc, mut associating): (
+                    Vec<Vec<String>>,
+                    Vec<String>,
+                    bool,
+                ),
+                 line| {
+                    let line = line.trim();
+
+                    // Don't associate our "Generated by" comment if it appears
+                    if line.starts_with("# Generated by") {
+                        return (all_assoc, current_assoc, associating);
+                    }
+
+                    if line.starts_with(NIX_CONF_COMMENT_CHAR) {
+                        associating = true;
+                    } else if line.is_empty() || !line.starts_with(NIX_CONF_COMMENT_CHAR) {
+                        associating = false;
+                    }
+
+                    current_assoc.push(line.to_string());
+
+                    if !associating {
+                        all_assoc.push(current_assoc);
+                        current_assoc = Vec::new();
+                    }
+
+                    (all_assoc, current_assoc, associating)
+                },
+            );
+
+            for line_group in associated_lines {
+                if line_group.is_empty() || line_group.iter().all(|line| line.is_empty()) {
+                    continue;
+                }
+
+                // This expect should never reasonably panic, because we would need a line group
+                // consisting solely of a comment and nothing else, but unconditionally appending a
+                // newline to the config string before grouping above prevents this from occurring.
+                let line_idx = line_group
+                    .iter()
+                    .position(|line| !line.starts_with(NIX_CONF_COMMENT_CHAR))
+                    .expect("There should always be one line without a comment character");
+
+                let setting_line = &line_group[line_idx];
+                let comments = line_group[..line_idx].join("\n");
+
+                // If we're here, but the line without a comment char is empty, we have
+                // standalone comments to preserve, but no settings with inline comments.
+                if setting_line.is_empty() {
+                    for line in &line_group {
+                        new_config.push_str(&line);
+                        new_config.push('\n');
+                    }
+
+                    continue;
+                }
+
+                // Preserve inline comments for settings we've merged
+                let to_remove = if let Some((name, value)) = existing_nix_config
+                    .settings()
+                    .iter()
+                    .find(|(name, _value)| setting_line.starts_with(*name))
+                {
+                    let inline_comment_idx =
+                        if let Some(idx) = setting_line.find(NIX_CONF_COMMENT_CHAR) {
+                            idx
+                        } else {
+                            continue;
+                        };
+
+                    let inline_comment = &setting_line[inline_comment_idx..];
+
+                    new_config.push_str(&comments);
+                    new_config.push('\n');
+                    new_config.push_str(name);
+                    new_config.push_str(" = ");
+
+                    if let Some(merged_value) = merged_nix_config.settings_mut().remove(name) {
+                        new_config.push_str(&merged_value);
+                        new_config.push(' ');
+                    } else {
+                        new_config.push_str(value);
+                    }
+
+                    new_config.push_str(inline_comment);
+                    new_config.push('\n');
+
+                    Some(name.clone())
+                } else {
+                    new_config.push_str(&comments);
+                    new_config.push('\n');
+                    new_config.push_str(setting_line);
+                    new_config.push('\n');
+
+                    None
+                };
+
+                if let Some(to_remove) = to_remove {
+                    existing_nix_config.settings_mut().remove(&to_remove);
+                }
+            }
+
+            // Add the leftover existing nix config
+            for (name, value) in existing_nix_config.settings() {
+                if merged_nix_config.settings().get(name).is_some() {
+                    continue;
+                }
+
+                new_config.push_str(name);
+                new_config.push_str(" = ");
+                new_config.push_str(value);
+                new_config.push('\n');
+            }
+
+            new_config.push('\n');
+        }
+
+        new_config.push_str(&format!(
+            "# Generated by https://github.com/DeterminateSystems/nix-installer, version {version}.\n",
+            version = env!("CARGO_PKG_VERSION"),
+        ));
+
+        for (name, value) in merged_nix_config.settings() {
+            new_config.push_str(name);
+            new_config.push_str(" = ");
+            new_config.push_str(value);
+            new_config.push('\n');
+        }
+
+        temp_file
+            .write_all(new_config.as_bytes())
+            .await
+            .map_err(|e| ActionError::Write(temp_file_path.clone(), e))?;
+        tokio::fs::set_permissions(&temp_file_path, PermissionsExt::from_mode(NIX_CONF_MODE))
+            .await
+            .map_err(|e| ActionError::SetPermissions(NIX_CONF_MODE, path.to_owned(), e))?;
+        tokio::fs::rename(&temp_file_path, &path)
+            .await
+            .map_err(|e| ActionError::Rename(temp_file_path.to_owned(), path.to_owned(), e))?;
+
+        Ok(())
+    }
+
+    fn revert_description(&self) -> Vec<ActionDescription> {
+        let Self {
+            path,
+            pending_nix_config: _,
+        } = &self;
+
+        vec![ActionDescription::new(
+            format!("Delete file `{}`", path.display()),
+            vec![format!("Delete file `{}`", path.display())],
+        )]
+    }
+
+    #[tracing::instrument(level = "debug", skip_all)]
+    async fn revert(&mut self) -> Result<(), ActionError> {
+        let Self {
+            path,
+            pending_nix_config: _,
+        } = self;
+
+        remove_file(&path)
+            .await
+            .map_err(|e| ActionError::Remove(path.to_owned(), e))?;
+
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use eyre::eyre;
+    use tokio::fs::write;
+
+    #[tokio::test]
+    async fn creates_and_deletes_file() -> eyre::Result<()> {
+        let temp_dir = tempfile::TempDir::new()?;
+        let test_file = temp_dir.path().join("creates_and_deletes_file");
+        let mut nix_config = NixConfig::new();
+        nix_config
+            .settings_mut()
+            .insert("experimental-features".into(), "ca-references".into());
+        let mut action = CreateOrMergeNixConfig::plan(&test_file, nix_config).await?;
+
+        action.try_execute().await?;
+
+        let s = std::fs::read_to_string(&test_file)?;
+        assert!(s.contains("# Generated by"));
+        assert!(s.contains("ca-references"));
+        assert!(NixConfig::parse_file(&test_file).is_ok());
+
+        action.try_revert().await?;
+
+        assert!(!test_file.exists(), "File should have been deleted");
+
+        Ok(())
+    }
+
+    #[tokio::test]
+    async fn creates_and_deletes_file_even_if_edited() -> eyre::Result<()> {
+        let temp_dir = tempfile::TempDir::new()?;
+        let test_file = temp_dir
+            .path()
+            .join("creates_and_deletes_file_even_if_edited");
+        let mut nix_config = NixConfig::new();
+        nix_config
+            .settings_mut()
+            .insert("experimental-features".into(), "ca-references".into());
+        let mut action = CreateOrMergeNixConfig::plan(&test_file, nix_config).await?;
+
+        action.try_execute().await?;
+
+        write(test_file.as_path(), "More content").await?;
+
+        action.try_revert().await?;
+
+        assert!(!test_file.exists(), "File should have been deleted");
+
+        Ok(())
+    }
+
+    #[tokio::test]
+    async fn recognizes_existing_exact_files_and_reverts_them() -> eyre::Result<()> {
+        let temp_dir = tempfile::TempDir::new()?;
+        let test_file = temp_dir
+            .path()
+            .join("recognizes_existing_exact_files_and_reverts_them");
+
+        let test_content = "experimental-features = flakes";
+        write(test_file.as_path(), test_content).await?;
+        tokio::fs::set_permissions(&test_file, PermissionsExt::from_mode(NIX_CONF_MODE)).await?;
+
+        let mut nix_config = NixConfig::new();
+        nix_config
+            .settings_mut()
+            .insert("experimental-features".into(), "flakes".into());
+        let mut action = CreateOrMergeNixConfig::plan(&test_file, nix_config).await?;
+
+        action.try_execute().await?;
+
+        action.try_revert().await?;
+
+        assert!(!test_file.exists(), "File should have been deleted");
+
+        Ok(())
+    }
+
+    #[tokio::test]
+    async fn recognizes_existing_different_files_and_merges() -> eyre::Result<()> {
+        let temp_dir = tempfile::TempDir::new()?;
+        let test_file = temp_dir
+            .path()
+            .join("recognizes_existing_different_files_and_merges");
+
+        write(
+            test_file.as_path(),
+            "experimental-features = flakes\nwarn-dirty = true\n",
+        )
+        .await?;
+        tokio::fs::set_permissions(&test_file, PermissionsExt::from_mode(NIX_CONF_MODE)).await?;
+
+        let mut nix_config = NixConfig::new();
+        nix_config
+            .settings_mut()
+            .insert("experimental-features".into(), "nix-command flakes".into());
+        nix_config
+            .settings_mut()
+            .insert("allow-dirty".into(), "false".into());
+        let mut action = CreateOrMergeNixConfig::plan(&test_file, nix_config).await?;
+
+        action.try_execute().await?;
+
+        let s = std::fs::read_to_string(&test_file)?;
+        assert!(s.contains("# Generated by"));
+        assert!(s.contains("flakes"));
+        assert!(s.contains("nix-command"));
+        assert_eq!(
+            s.matches("flakes").count(),
+            1,
+            "we should not duplicate strings"
+        );
+        assert!(s.contains("allow-dirty = false"));
+        assert!(s.contains("warn-dirty = true"));
+        assert!(NixConfig::parse_file(&test_file).is_ok());
+
+        action.try_revert().await?;
+
+        assert!(!test_file.exists(), "File should have been deleted");
+
+        Ok(())
+    }
+
+    #[tokio::test]
+    async fn recognizes_existing_different_files_and_fails_to_merge() -> eyre::Result<()> {
+        let temp_dir = tempfile::TempDir::new()?;
+        let test_file = temp_dir
+            .path()
+            .join("recognizes_existing_different_files_and_fails_to_merge");
+
+        write(
+            test_file.as_path(),
+            "experimental-features = flakes\nwarn-dirty = true\n",
+        )
+        .await?;
+
+        let mut nix_config = NixConfig::new();
+        nix_config
+            .settings_mut()
+            .insert("experimental-features".into(), "nix-command flakes".into());
+        nix_config
+            .settings_mut()
+            .insert("warn-dirty".into(), "false".into());
+        match CreateOrMergeNixConfig::plan(&test_file, nix_config).await {
+            Err(ActionError::Custom(e)) => match e.downcast_ref::<CreateOrMergeNixConfigError>() {
+                Some(CreateOrMergeNixConfigError::UnmergeableConfig(_, path)) => {
+                    assert_eq!(path, test_file.as_path())
+                },
+                _ => {
+                    return Err(eyre!(
+                        "Should have returned CreateOrMergeNixConfigError::UnmergeableConfig"
+                    ))
+                },
+            },
+            _ => {
+                return Err(eyre!(
+                    "Should have returned CreateOrMergeNixConfigError::UnmergeableConfig"
+                ))
+            },
+        }
+
+        assert!(test_file.exists(), "File should not have been deleted");
+
+        Ok(())
+    }
+
+    #[tokio::test]
+    async fn preserves_comments() -> eyre::Result<()> {
+        let temp_dir = tempfile::TempDir::new()?;
+        let test_file = temp_dir.path().join("preserves_comments");
+
+        write(
+            test_file.as_path(),
+            "# test 2\n# test\nexperimental-features = flakes # some inline comment about experimental-features\n# the following line should be warn-dirty = true\nwarn-dirty = true # this is an inline comment\n# this is an ungrouped comment\n# this too",
+        )
+        .await?;
+        let mut nix_config = NixConfig::new();
+        nix_config
+            .settings_mut()
+            .insert("experimental-features".into(), "ca-references".into());
+        let mut action = CreateOrMergeNixConfig::plan(&test_file, nix_config).await?;
+
+        action.try_execute().await?;
+
+        let s = std::fs::read_to_string(&test_file)?;
+        assert!(s.contains("# the following line should be warn-dirty = true\nwarn-dirty = true"));
+        assert!(s.contains("# test 2\n# test\nexperimental-features"));
+        assert!(s.contains("# this is an inline comment"));
+        assert!(s.contains("# some inline comment about experimental-features"));
+        assert!(s.contains("# Generated by"));
+        assert!(s.contains("# this is an ungrouped comment\n# this too"));
+        assert!(s.contains("ca-references"));
+        assert!(NixConfig::parse_file(&test_file).is_ok());
+
+        action.try_revert().await?;
+
+        assert!(!test_file.exists(), "File should have been deleted");
+
+        Ok(())
+    }
+
+    #[tokio::test]
+    async fn preserves_comments_edge_case() -> eyre::Result<()> {
+        let temp_dir = tempfile::TempDir::new()?;
+        let test_file = temp_dir.path().join("preserves_comments");
+
+        write(test_file.as_path(), " a = b\n c = d# lol\n# e = f").await?;
+        let mut nix_config = NixConfig::new();
+        nix_config
+            .settings_mut()
+            .insert("experimental-features".into(), "ca-references".into());
+        let mut action = CreateOrMergeNixConfig::plan(&test_file, nix_config).await?;
+
+        action.try_execute().await?;
+
+        let s = std::fs::read_to_string(&test_file)?;
+        assert!(s.contains("# Generated by"));
+        assert!(s.contains("ca-references"));
+        assert_eq!(s.matches("a = b").count(), 1);
+        assert!(NixConfig::parse_file(&test_file).is_ok());
+
+        action.try_revert().await?;
+
+        assert!(!test_file.exists(), "File should have been deleted");
+
+        Ok(())
+    }
+}

src/action/base/mod.rs

@@ -5,6 +5,7 @@ pub(crate) mod create_directory;
 pub(crate) mod create_file;
 pub(crate) mod create_group;
 pub(crate) mod create_or_insert_into_file;
+pub(crate) mod create_or_merge_nix_config;
 pub(crate) mod create_user;
 pub(crate) mod fetch_and_unpack_nix;
 pub(crate) mod move_unpacked_nix;
@@ -15,6 +16,7 @@ pub use create_directory::CreateDirectory;
 pub use create_file::CreateFile;
 pub use create_group::CreateGroup;
 pub use create_or_insert_into_file::CreateOrInsertIntoFile;
+pub use create_or_merge_nix_config::CreateOrMergeNixConfig;
 pub use create_user::CreateUser;
 pub use fetch_and_unpack_nix::{FetchAndUnpackNix, FetchUrlError};
 pub use move_unpacked_nix::{MoveUnpackedNix, MoveUnpackedNixError};

src/action/common/place_nix_configuration.rs

@@ -1,6 +1,7 @@
 use tracing::{span, Span};
 
-use crate::action::base::{CreateDirectory, CreateFile};
+use crate::action::base::create_or_merge_nix_config::CreateOrMergeNixConfigError;
+use crate::action::base::{CreateDirectory, CreateOrMergeNixConfig};
 use crate::action::{Action, ActionDescription, ActionError, ActionTag, StatefulAction};
 
 const NIX_CONF_FOLDER: &str = "/etc/nix";
@@ -12,7 +13,7 @@ Place the `/etc/nix.conf` file
 #[derive(Debug, serde::Deserialize, serde::Serialize, Clone)]
 pub struct PlaceNixConfiguration {
     create_directory: StatefulAction<CreateDirectory>,
-    create_file: StatefulAction<CreateFile>,
+    create_or_merge_nix_config: StatefulAction<CreateOrMergeNixConfig>,
 }
 
 impl PlaceNixConfiguration {
@@ -22,34 +23,38 @@ impl PlaceNixConfiguration {
         extra_conf: Vec<String>,
         force: bool,
     ) -> Result<StatefulAction<Self>, ActionError> {
-        let buf = format!(
+        let extra_conf = extra_conf.join("\n");
-            "\
+        let mut nix_config = nix_config_parser::NixConfig::parse_string(extra_conf, None)
-            # Generated by https://github.com/DeterminateSystems/nix-installer, version {version}.\n\
+            .map_err(CreateOrMergeNixConfigError::ParseNixConfig)
-            \n\
+            .map_err(|e| ActionError::Custom(Box::new(e)))?;
-            {extra_conf}\n\
+        let settings = nix_config.settings_mut();
-            \n\
+
-            build-users-group = {nix_build_group_name}\n\
+        settings.insert("build-users-group".to_string(), nix_build_group_name);
-            \n\
+        settings.insert(
-            experimental-features = nix-command flakes\n\
+            "experimental-features".to_string(),
-            \n\
+            "nix-command flakes".to_string(),
-            auto-optimise-store = true\n\
-            \n\
-            bash-prompt-prefix = (nix:$name)\\040\n\
-            \n\
-            extra-nix-path = nixpkgs=flake:nixpkgs\n\
-        ",
-            extra_conf = extra_conf.join("\n"),
-            version = env!("CARGO_PKG_VERSION"),
         );
+        settings.insert("auto-optimise-store".to_string(), "true".to_string());
+        settings.insert(
+            "bash-prompt-prefix".to_string(),
+            "(nix:$name)\\040".to_string(),
+        );
+        settings.insert(
+            "extra-nix-path".to_string(),
+            "nixpkgs=flake:nixpkgs".to_string(),
+        );
+
         let create_directory = CreateDirectory::plan(NIX_CONF_FOLDER, None, None, 0o0755, force)
             .await
             .map_err(|e| ActionError::Child(CreateDirectory::action_tag(), Box::new(e)))?;
-        let create_file = CreateFile::plan(NIX_CONF, None, None, 0o0664, buf, force)
+        let create_or_merge_nix_config = CreateOrMergeNixConfig::plan(NIX_CONF, nix_config)
             .await
-            .map_err(|e| ActionError::Child(CreateFile::action_tag(), Box::new(e)))?;
+            .map_err(|e| {
+            ActionError::Child(CreateOrMergeNixConfig::action_tag(), Box::new(e))
+        })?;
         Ok(Self {
             create_directory,
-            create_file,
+            create_or_merge_nix_config,
         }
         .into())
     }
@@ -70,13 +75,24 @@ impl Action for PlaceNixConfiguration {
     }
 
     fn execute_description(&self) -> Vec<ActionDescription> {
-        vec![ActionDescription::new(
+        let Self {
-            self.tracing_synopsis(),
+            create_or_merge_nix_config,
-            vec![
+            create_directory,
+        } = self;
+
+        let mut explanation = vec![
             "This file is read by the Nix daemon to set its configuration options at runtime."
                 .to_string(),
-            ],
+        ];
-        )]
+
+        if let Some(val) = create_directory.describe_execute().iter().next() {
+            explanation.push(val.description.clone())
+        }
+        for val in create_or_merge_nix_config.describe_execute().iter() {
+            explanation.push(val.description.clone())
+        }
+
+        vec![ActionDescription::new(self.tracing_synopsis(), explanation)]
     }
 
     #[tracing::instrument(level = "debug", skip_all)]
@@ -85,10 +101,12 @@ impl Action for PlaceNixConfiguration {
             .try_execute()
             .await
             .map_err(|e| ActionError::Child(self.create_directory.action_tag(), Box::new(e)))?;
-        self.create_file
+        self.create_or_merge_nix_config
             .try_execute()
             .await
-            .map_err(|e| ActionError::Child(self.create_file.action_tag(), Box::new(e)))?;
+            .map_err(|e| {
+                ActionError::Child(self.create_or_merge_nix_config.action_tag(), Box::new(e))
+            })?;
 
         Ok(())
     }
@@ -105,10 +123,12 @@ impl Action for PlaceNixConfiguration {
 
     #[tracing::instrument(level = "debug", skip_all)]
     async fn revert(&mut self) -> Result<(), ActionError> {
-        self.create_file
+        self.create_or_merge_nix_config
             .try_revert()
             .await
-            .map_err(|e| ActionError::Child(self.create_file.action_tag(), Box::new(e)))?;
+            .map_err(|e| {
+                ActionError::Child(self.create_or_merge_nix_config.action_tag(), Box::new(e))
+            })?;
         self.create_directory
             .try_revert()
             .await

tests/fixtures/linux/linux.json

@@ -17,7 +17,7 @@
         "action": "provision_nix",
         "fetch_nix": {
           "action": {
-            "url": "https://releases.nixos.org/nix/nix-2.12.0/nix-2.12.0-x86_64-linux.tar.xz",
+            "url": "https://releases.nixos.org/nix/nix-2.13.2/nix-2.13.2-x86_64-linux.tar.xz",
             "dest": "/nix/temp-install-dir"
           },
           "state": "Uncompleted"
@@ -788,7 +788,7 @@
                   "path": "/etc/bashrc",
                   "user": null,
                   "group": null,
-                  "mode": 493,
+                  "mode": 33188,
                   "buf": "\n# Nix\nif [ -e '/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh' ]; then\n    . '/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh'\nfi\n# End Nix\n\n        \n",
                   "position": "Beginning"
                 },
@@ -799,7 +799,7 @@
                   "path": "/etc/profile.d/nix.sh",
                   "user": null,
                   "group": null,
-                  "mode": 493,
+                  "mode": 33188,
                   "buf": "\n# Nix\nif [ -e '/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh' ]; then\n    . '/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh'\nfi\n# End Nix\n\n        \n",
                   "position": "Beginning"
                 },
@@ -810,7 +810,7 @@
                   "path": "/etc/zshenv",
                   "user": null,
                   "group": null,
-                  "mode": 493,
+                  "mode": 33188,
                   "buf": "\n# Nix\nif [ -e '/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh' ]; then\n    . '/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh'\nfi\n# End Nix\n\n        \n",
                   "position": "Beginning"
                 },
@@ -821,7 +821,7 @@
                   "path": "/etc/bash.bashrc",
                   "user": null,
                   "group": null,
-                  "mode": 493,
+                  "mode": 33188,
                   "buf": "\n# Nix\nif [ -e '/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh' ]; then\n    . '/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh'\nfi\n# End Nix\n\n        \n",
                   "position": "Beginning"
                 },
@@ -841,7 +841,7 @@
             ],
             "create_file": {
               "action": {
-                "path": "/home/ana/.nix-channels",
+                "path": "/root/.nix-channels",
                 "user": null,
                 "group": null,
                 "mode": 436,
@@ -865,14 +865,17 @@
               },
               "state": "Uncompleted"
             },
-            "create_file": {
+            "create_or_merge_nix_config": {
               "action": {
                 "path": "/etc/nix/nix.conf",
-                "user": null,
+                "pending_nix_config": {
-                "group": null,
+                  "settings": {
-                "mode": 436,
+                    "bash-prompt-prefix": "(nix:$name)\\040",
-                "buf": "# Generated by https://github.com/DeterminateSystems/nix-installer, version 0.1.0-unreleased.\n\n\n\nbuild-users-group = nixbld\n\nexperimental-features = nix-command flakes\n\nauto-optimise-store = true\n\nbash-prompt-prefix = (nix:$name)\\040\n",
+                    "build-users-group": "nixbld",
-                "force": false
+                    "auto-optimise-store": "true",
+                    "experimental-features": "nix-command flakes"
+                  }
+                }
               },
               "state": "Uncompleted"
             }
@@ -906,7 +909,7 @@
       "nix_build_group_id": 3000,
       "nix_build_user_prefix": "nixbld",
       "nix_build_user_id_base": 3000,
-      "nix_package_url": "https://releases.nixos.org/nix/nix-2.12.0/nix-2.12.0-x86_64-linux.tar.xz",
+      "nix_package_url": "https://releases.nixos.org/nix/nix-2.13.2/nix-2.13.2-x86_64-linux.tar.xz",
       "extra_conf": [],
       "force": false
     },

tests/fixtures/linux/steam-deck.json

@@ -4,7 +4,7 @@
     {
       "action": {
         "action": "create_directory",
-        "path": "/nix",
+        "path": "/home/nix",
         "user": null,
         "group": null,
         "mode": 493,
@@ -12,6 +12,50 @@
       },
       "state": "Uncompleted"
     },
+    {
+      "action": {
+        "action": "create_file",
+        "path": "/etc/systemd/system/nix-directory.service",
+        "user": null,
+        "group": null,
+        "mode": 420,
+        "buf": "[Unit]\nDescription=Create a `/nix` directory to be used for bind mounting\nPropagatesStopTo=nix-daemon.service\nPropagatesStopTo=nix.mount\nDefaultDependencies=no\nAfter=grub-recordfail.service\nAfter=steamos-finish-oobe-migration.service\n\n[Service]\nType=oneshot\nExecStart=steamos-readonly disable\nExecStart=mkdir -vp /nix\nExecStart=chmod -v 0755 /nix\nExecStart=chown -v root /nix\nExecStart=chgrp -v root /nix\nExecStart=steamos-readonly enable\nExecStop=steamos-readonly disable\nExecStop=rmdir /nix\nExecStop=steamos-readonly enable\nRemainAfterExit=true\n",
+        "force": false
+      },
+      "state": "Uncompleted"
+    },
+    {
+      "action": {
+        "action": "create_file",
+        "path": "/etc/systemd/system/nix.mount",
+        "user": null,
+        "group": null,
+        "mode": 420,
+        "buf": "[Unit]\nDescription=Mount `/home/nix` on `/nix`\nPropagatesStopTo=nix-daemon.service\nPropagatesStopTo=nix-directory.service\nAfter=nix-directory.service\nRequires=nix-directory.service\nConditionPathIsDirectory=/nix\nDefaultDependencies=no\nRequiredBy=nix-daemon.service\nRequiredBy=nix-daemon.socket\n\n[Mount]\nWhat=/home/nix\nWhere=/nix\nType=none\nDirectoryMode=0755\nOptions=bind\n",
+        "force": false
+      },
+      "state": "Uncompleted"
+    },
+    {
+      "action": {
+        "action": "create_file",
+        "path": "/etc/systemd/system/ensure-symlinked-units-resolve.service",
+        "user": null,
+        "group": null,
+        "mode": 420,
+        "buf": "[Unit]\nDescription=Ensure Nix related units which are symlinked resolve\nAfter=nix.mount\nRequires=nix-directory.service\nRequires=nix.mount\nDefaultDependencies=no\n\n[Service]\nType=oneshot\nRemainAfterExit=yes\nExecStart=/usr/bin/systemctl daemon-reload\nExecStart=/usr/bin/systemctl restart --no-block nix-daemon.socket\n\n[Install]\nWantedBy=sysinit.target\n",
+        "force": false
+      },
+      "state": "Uncompleted"
+    },
+    {
+      "action": {
+        "action": "start_systemd_unit",
+        "unit": "nix.mount",
+        "enable": false
+      },
+      "state": "Uncompleted"
+    },
     {
       "action": {
         "action": "provision_nix",
@@ -26,13 +70,13 @@
           "action": {
             "nix_build_user_count": 32,
             "nix_build_group_name": "nixbld",
-            "nix_build_group_id": 3000,
+            "nix_build_group_id": 30000,
             "nix_build_user_prefix": "nixbld",
-            "nix_build_user_id_base": 3000,
+            "nix_build_user_id_base": 30000,
             "create_group": {
               "action": {
                 "name": "nixbld",
-                "gid": 3000
+                "gid": 30000
               },
               "state": "Uncompleted"
             },
@@ -40,288 +84,288 @@
               {
                 "action": {
                   "name": "nixbld0",
-                  "uid": 3000,
+                  "uid": 30000,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld1",
-                  "uid": 3001,
+                  "uid": 30001,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld2",
-                  "uid": 3002,
+                  "uid": 30002,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld3",
-                  "uid": 3003,
+                  "uid": 30003,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld4",
-                  "uid": 3004,
+                  "uid": 30004,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld5",
-                  "uid": 3005,
+                  "uid": 30005,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld6",
-                  "uid": 3006,
+                  "uid": 30006,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld7",
-                  "uid": 3007,
+                  "uid": 30007,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld8",
-                  "uid": 3008,
+                  "uid": 30008,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld9",
-                  "uid": 3009,
+                  "uid": 30009,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld10",
-                  "uid": 3010,
+                  "uid": 30010,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld11",
-                  "uid": 3011,
+                  "uid": 30011,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld12",
-                  "uid": 3012,
+                  "uid": 30012,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld13",
-                  "uid": 3013,
+                  "uid": 30013,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld14",
-                  "uid": 3014,
+                  "uid": 30014,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld15",
-                  "uid": 3015,
+                  "uid": 30015,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld16",
-                  "uid": 3016,
+                  "uid": 30016,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld17",
-                  "uid": 3017,
+                  "uid": 30017,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld18",
-                  "uid": 3018,
+                  "uid": 30018,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld19",
-                  "uid": 3019,
+                  "uid": 30019,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld20",
-                  "uid": 3020,
+                  "uid": 30020,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld21",
-                  "uid": 3021,
+                  "uid": 30021,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld22",
-                  "uid": 3022,
+                  "uid": 30022,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld23",
-                  "uid": 3023,
+                  "uid": 30023,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld24",
-                  "uid": 3024,
+                  "uid": 30024,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld25",
-                  "uid": 3025,
+                  "uid": 30025,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld26",
-                  "uid": 3026,
+                  "uid": 30026,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld27",
-                  "uid": 3027,
+                  "uid": 30027,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld28",
-                  "uid": 3028,
+                  "uid": 30028,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld29",
-                  "uid": 3029,
+                  "uid": 30029,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld30",
-                  "uid": 3030,
+                  "uid": 30030,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld31",
-                  "uid": 3031,
+                  "uid": 30031,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               }
@@ -330,288 +374,288 @@
               {
                 "action": {
                   "name": "nixbld0",
-                  "uid": 3000,
+                  "uid": 30000,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld1",
-                  "uid": 3001,
+                  "uid": 30001,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld2",
-                  "uid": 3002,
+                  "uid": 30002,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld3",
-                  "uid": 3003,
+                  "uid": 30003,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld4",
-                  "uid": 3004,
+                  "uid": 30004,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld5",
-                  "uid": 3005,
+                  "uid": 30005,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld6",
-                  "uid": 3006,
+                  "uid": 30006,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld7",
-                  "uid": 3007,
+                  "uid": 30007,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld8",
-                  "uid": 3008,
+                  "uid": 30008,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld9",
-                  "uid": 3009,
+                  "uid": 30009,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld10",
-                  "uid": 3010,
+                  "uid": 30010,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld11",
-                  "uid": 3011,
+                  "uid": 30011,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld12",
-                  "uid": 3012,
+                  "uid": 30012,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld13",
-                  "uid": 3013,
+                  "uid": 30013,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld14",
-                  "uid": 3014,
+                  "uid": 30014,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld15",
-                  "uid": 3015,
+                  "uid": 30015,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld16",
-                  "uid": 3016,
+                  "uid": 30016,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld17",
-                  "uid": 3017,
+                  "uid": 30017,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld18",
-                  "uid": 3018,
+                  "uid": 30018,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld19",
-                  "uid": 3019,
+                  "uid": 30019,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld20",
-                  "uid": 3020,
+                  "uid": 30020,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld21",
-                  "uid": 3021,
+                  "uid": 30021,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld22",
-                  "uid": 3022,
+                  "uid": 30022,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld23",
-                  "uid": 3023,
+                  "uid": 30023,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld24",
-                  "uid": 3024,
+                  "uid": 30024,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld25",
-                  "uid": 3025,
+                  "uid": 30025,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld26",
-                  "uid": 3026,
+                  "uid": 30026,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld27",
-                  "uid": 3027,
+                  "uid": 30027,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld28",
-                  "uid": 3028,
+                  "uid": 30028,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld29",
-                  "uid": 3029,
+                  "uid": 30029,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld30",
-                  "uid": 3030,
+                  "uid": 30030,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               },
               {
                 "action": {
                   "name": "nixbld31",
-                  "uid": 3031,
+                  "uid": 30031,
                   "groupname": "nixbld",
-                  "gid": 3000
+                  "gid": 30000
                 },
                 "state": "Uncompleted"
               }
@@ -781,18 +825,7 @@
         },
         "configure_shell_profile": {
           "action": {
-            "create_directories": [
+            "create_directories": [],
-              {
-                "action": {
-                  "path": "/etc/fish/conf.d",
-                  "user": null,
-                  "group": null,
-                  "mode": 420,
-                  "force_prune_on_revert": false
-                },
-                "state": "Skipped"
-              }
-            ],
             "create_or_insert_into_files": [
               {
                 "action": {
@@ -837,17 +870,6 @@
                   "position": "Beginning"
                 },
                 "state": "Uncompleted"
-              },
-              {
-                "action": {
-                  "path": "/etc/fish/conf.d/nix.fish",
-                  "user": null,
-                  "group": null,
-                  "mode": 33188,
-                  "buf": "\n# Nix\nif test -e '/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.fish'\n    . '/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.fish'\nend\n# End Nix\n\n",
-                  "position": "Beginning"
-                },
-                "state": "Uncompleted"
               }
             ]
           },
@@ -863,7 +885,7 @@
             ],
             "create_file": {
               "action": {
-                "path": "/home/deck/.nix-channels",
+                "path": "/home/ubuntu/.nix-channels",
                 "user": null,
                 "group": null,
                 "mode": 436,
@@ -887,14 +909,17 @@
               },
               "state": "Uncompleted"
             },
-            "create_file": {
+            "create_or_merge_nix_config": {
               "action": {
                 "path": "/etc/nix/nix.conf",
-                "user": null,
+                "pending_nix_config": {
-                "group": null,
+                  "settings": {
-                "mode": 436,
+                    "bash-prompt-prefix": "(nix:$name)\\040",
-                "buf": "# Generated by https://github.com/DeterminateSystems/nix-installer, version 0.3.0.\n\n\n\nbuild-users-group = nixbld\n\nexperimental-features = nix-command flakes\n\nauto-optimise-store = true\n\nbash-prompt-prefix = (nix:$name)\\040\n",
+                    "build-users-group": "nixbld",
-                "force": false
+                    "auto-optimise-store": "true",
+                    "experimental-features": "nix-command flakes"
+                  }
+                }
               },
               "state": "Uncompleted"
             }
@@ -911,10 +936,19 @@
         "start_daemon": true
       },
       "state": "Uncompleted"
+    },
+    {
+      "action": {
+        "action": "start_systemd_unit",
+        "unit": "ensure-symlinked-units-resolve.service",
+        "enable": true
+      },
+      "state": "Uncompleted"
     }
   ],
   "planner": {
-    "planner": "linux",
+    "planner": "steam-deck",
+    "persistence": "/home/nix",
     "settings": {
       "channels": [
         [
@@ -925,16 +959,12 @@
       "modify_profile": true,
       "nix_build_user_count": 32,
       "nix_build_group_name": "nixbld",
-      "nix_build_group_id": 3000,
+      "nix_build_group_id": 30000,
       "nix_build_user_prefix": "nixbld",
-      "nix_build_user_id_base": 3000,
+      "nix_build_user_id_base": 30000,
       "nix_package_url": "https://releases.nixos.org/nix/nix-2.13.2/nix-2.13.2-x86_64-linux.tar.xz",
       "extra_conf": [],
       "force": false
-    },
-    "init": {
-      "init": "Systemd",
-      "start_daemon": true
     }
   }
 }

tests/fixtures/macos/macos.json

@@ -4,7 +4,7 @@
     {
       "action": {
         "action": "create_apfs_volume",
-        "disk": "disk3",
+        "disk": "disk1",
         "name": "Nix Store",
         "case_sensitive": false,
         "encrypt": true,
@@ -25,14 +25,14 @@
         },
         "unmount_volume": {
           "action": {
-            "disk": "disk3",
+            "disk": "disk1",
             "name": "Nix Store"
           },
           "state": "Uncompleted"
         },
         "create_volume": {
           "action": {
-            "disk": "disk3",
+            "disk": "disk1",
             "name": "Nix Store",
             "case_sensitive": false
           },
@@ -46,7 +46,7 @@
         },
         "encrypt_volume": {
           "action": {
-            "disk": "disk3",
+            "disk": "disk1",
             "name": "Nix Store"
           },
           "state": "Uncompleted"
@@ -82,7 +82,7 @@
         "action": "provision_nix",
         "fetch_nix": {
           "action": {
-            "url": "https://releases.nixos.org/nix/nix-2.13.2/nix-2.13.2-aarch64-darwin.tar.xz",
+            "url": "https://releases.nixos.org/nix/nix-2.13.2/nix-2.13.2-x86_64-darwin.tar.xz",
             "dest": "/nix/temp-install-dir"
           },
           "state": "Uncompleted"
@@ -919,14 +919,17 @@
               },
               "state": "Uncompleted"
             },
-            "create_file": {
+            "create_or_merge_nix_config": {
               "action": {
                 "path": "/etc/nix/nix.conf",
-                "user": null,
+                "pending_nix_config": {
-                "group": null,
+                  "settings": {
-                "mode": 436,
+                    "bash-prompt-prefix": "(nix:$name)\\040",
-                "buf": "# Generated by https://github.com/DeterminateSystems/nix-installer, version 0.3.0.\n\n\n\nbuild-users-group = nixbld\n\nexperimental-features = nix-command flakes\n\nauto-optimise-store = true\n\nbash-prompt-prefix = (nix:$name)\\040\n",
+                    "auto-optimise-store": "true",
-                "force": false
+                    "build-users-group": "nixbld",
+                    "experimental-features": "nix-command flakes"
+                  }
+                }
               },
               "state": "Uncompleted"
             }
@@ -960,13 +963,13 @@
       "nix_build_group_id": 3000,
       "nix_build_user_prefix": "_nixbld",
       "nix_build_user_id_base": 300,
-      "nix_package_url": "https://releases.nixos.org/nix/nix-2.13.2/nix-2.13.2-aarch64-darwin.tar.xz",
+      "nix_package_url": "https://releases.nixos.org/nix/nix-2.13.2/nix-2.13.2-x86_64-darwin.tar.xz",
       "extra_conf": [],
       "force": false
     },
     "encrypt": null,
     "case_sensitive": false,
     "volume_label": "Nix Store",
-    "root_disk": "disk3"
+    "root_disk": "disk1"
   }
 }