Use flake-schemas for nix flake show (#166)

This uses the still WIP flake schemas feature implemented in NixOS/nix#8892 with our own fix for Intel Mac.

crates/nix_rs/CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+- **DeterminateSystems/flake-schemas**
+  - Allow overriding the `nix` CLI command.
+  - Switch to flake schema given by <https://github.com/DeterminateSystems/flake-schemas>
 - **`flake::schema::FlakeSchema`**
   - Add `nixos_configurations`
 - **`flake::url`**

crates/nix_rs/src/command.rs

@@ -40,6 +40,10 @@ pub struct NixCmd {
     /// Consider all previously downloaded files out-of-date.
     #[cfg_attr(feature = "clap", arg(long))]
     pub refresh: bool,
+
+    /// The command to run instead of `nix`.
+    #[cfg_attr(feature = "clap", arg(long))]
+    pub command: Option<String>,
 }
 
 impl Default for NixCmd {
@@ -51,6 +55,7 @@ impl Default for NixCmd {
             extra_experimental_features: vec![],
             extra_access_tokens: vec![],
             refresh: false,
+            command: None,
         }
     }
 }
@@ -94,7 +99,7 @@ impl NixCmd {
 
     /// Return a [Command] for this [NixCmd] configuration
     pub fn command(&self) -> Command {
-        let mut cmd = Command::new("nix");
+        let mut cmd = Command::new(self.command.as_deref().unwrap_or("nix"));
         cmd.kill_on_drop(true);
         cmd.args(self.args());
         cmd

crates/nix_rs/src/flake/outputs.rs

@@ -6,12 +6,22 @@ use std::{
     fmt::Display,
 };
 
+/// Absolute path to the `nix` binary compiled with flake schemas support
+///
+/// We expect this environment to be set in Nix build and shell.
+pub const NIX_FLAKE_SCHEMAS_BIN: &str = env!("NIX_FLAKE_SCHEMAS_BIN");
+
+/// Flake URL of the default flake schemas
+///
+/// We expect this environment to be set in Nix build and shell.
+pub const DEFAULT_FLAKE_SCHEMAS: &str = env!("DEFAULT_FLAKE_SCHEMAS");
+
 /// Represents the "outputs" of a flake
 ///
 /// This structure is currently produced by `nix flake show`, thus to parse it we must toggle serde untagged.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub enum FlakeOutputs {
-    Val(Val),
+    Leaf(Leaf),
     Attrset(BTreeMap<String, FlakeOutputs>),
 }
 
@@ -25,10 +35,10 @@ impl FlakeOutputs {
         Ok(v.into_flake_outputs())
     }
 
-    /// Get the non-attrset value
-    pub fn as_leaf(&self) -> Option<&Val> {
+    /// Get the non-attrset leaf
+    pub fn as_leaf(&self) -> Option<&Leaf> {
         match self {
-            Self::Val(v) => Some(v),
+            Self::Leaf(v) => Some(v),
             _ => None,
         }
     }
@@ -68,25 +78,94 @@ impl FlakeOutputs {
     }
 }
 
+/// Represents a leaf value of a flake output
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(untagged)]
+pub enum Leaf {
+    Val(Val),
+    Unknown(Unknown),
+    Filtered(Filtered),
+    Skipped(Skipped),
+    /// Represents description for a flake output
+    /// (e.g. `Doc` for `formatter` will be "The `formatter` output specifies the package to use to format the project.")
+    Doc(String),
+}
+
+impl Leaf {
+    /// Get the value as a [Val]
+    pub fn as_val(&self) -> Option<&Val> {
+        match self {
+            Self::Val(v) => Some(v),
+            _ => None,
+        }
+    }
+}
+
 /// The metadata of a flake output value which is of non-attrset [Type]
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct Val {
-    #[serde(rename = "type")]
+    #[serde(rename = "what")]
     pub type_: Type,
-    pub name: Option<String>,
-    pub description: Option<String>,
+    pub derivation_name: Option<String>,
+    pub short_description: Option<String>,
+}
+
+impl Default for Val {
+    fn default() -> Self {
+        Self {
+            type_: Type::Unknown,
+            derivation_name: None,
+            short_description: None,
+        }
+    }
+}
+
+/// Boolean flags at the leaf of a flake output
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct Unknown {
+    pub unknown: bool,
+}
+
+/// Represents flake outputs that cannot be evaluated on current platform
+/// (e.g. `nixosConfigurations` on darwin System)
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename = "camelCase")]
+pub struct Filtered {
+    pub filtered: bool,
+}
+
+/// Represents flake outputs that are skipped unless explicitly requested
+/// (e.g. `legacyPackages`)
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct Skipped {
+    pub skipped: bool,
 }
 
 /// The type of a flake output [Val]
 ///
-/// [Nix source ref](https://github.com/NixOS/nix/blob/2.14.1/src/nix/flake.cc#L1105)
+/// These types can differ based on [DEFAULT_FLAKE_SCHEMAS].
+/// The types here are based on <https://github.com/DeterminateSystems/flake-schemas>
+/// For example, see [NixosModule type](https://github.com/DeterminateSystems/flake-schemas/blob/0a5c42297d870156d9c57d8f99e476b738dcd982/flake.nix#L268)
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-#[serde(rename_all = "camelCase")]
 pub enum Type {
+    #[serde(rename = "NixOS module")]
     NixosModule,
-    Derivation,
+    #[serde(rename = "NixOS configuration")]
+    NixosConfiguration,
+    #[serde(rename = "nix-darwin configuration")]
+    DarwinConfiguration,
+    #[serde(rename = "package")]
+    Package,
+    #[serde(rename = "development environment")]
+    DevShell,
+    #[serde(rename = "CI test")]
+    Check,
+    #[serde(rename = "app")]
     App,
+    #[serde(rename = "template")]
     Template,
     #[serde(other)]
     Unknown,
@@ -97,7 +176,11 @@ impl Type {
     pub fn to_icon(&self) -> &'static str {
         match self {
             Self::NixosModule => "❄️",
-            Self::Derivation => "📦",
+            Self::NixosConfiguration => "🔧",
+            Self::DarwinConfiguration => "🍎",
+            Self::Package => "📦",
+            Self::DevShell => "🐚",
+            Self::Check => "🧪",
             Self::App => "📱",
             Self::Template => "🏗️",
             Self::Unknown => "❓",
@@ -117,7 +200,7 @@ impl Display for Type {
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(untagged)]
 enum FlakeOutputsUntagged {
-    UVal(Val),
+    ULeaf(Leaf),
     UAttrset(BTreeMap<String, FlakeOutputsUntagged>),
 }
 
@@ -128,13 +211,18 @@ impl FlakeOutputsUntagged {
         nix_cmd: &crate::command::NixCmd,
         flake_url: &super::url::FlakeUrl,
     ) -> Result<Self, crate::command::NixCmdError> {
-        let v = nix_cmd
+        let mut nix_flake_schemas_cmd = nix_cmd.clone();
+        nix_flake_schemas_cmd.command = Some(env!("NIX_FLAKE_SCHEMAS_BIN").to_string());
+
+        let v = nix_flake_schemas_cmd
             .run_with_args_expecting_json(&[
                 "flake",
                 "show",
                 "--legacy", // for showing nixpkgs legacyPackages
                 "--allow-import-from-derivation",
                 "--json",
+                "--default-flake-schemas",
+                env!("DEFAULT_FLAKE_SCHEMAS"),
                 &flake_url.to_string(),
             ])
             .await?;
@@ -144,7 +232,7 @@ impl FlakeOutputsUntagged {
     /// Convert to [FlakeOutputs]
     fn into_flake_outputs(self) -> FlakeOutputs {
         match self {
-            Self::UVal(v) => FlakeOutputs::Val(v),
+            Self::ULeaf(v) => FlakeOutputs::Leaf(v),
             Self::UAttrset(v) => FlakeOutputs::Attrset(
                 v.into_iter()
                     .map(|(k, v)| (k, v.into_flake_outputs()))

crates/nix_rs/src/flake/schema.rs

@@ -6,7 +6,7 @@ use std::collections::BTreeMap;
 use serde::{Deserialize, Serialize};
 
 use super::{
-    outputs::{FlakeOutputs, Val},
+    outputs::{FlakeOutputs, Leaf},
     System,
 };
 
@@ -16,16 +16,22 @@ use super::{
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct FlakeSchema {
     pub system: System,
-    pub packages: BTreeMap<String, Val>,
-    pub legacy_packages: BTreeMap<String, Val>,
-    pub devshells: BTreeMap<String, Val>,
-    pub checks: BTreeMap<String, Val>,
-    pub apps: BTreeMap<String, Val>,
-    pub formatter: Option<Val>,
-    pub nixos_configurations: BTreeMap<String, Val>,
+    pub packages: BTreeMap<String, Leaf>,
+    pub legacy_packages: BTreeMap<String, Leaf>,
+    pub devshells: BTreeMap<String, Leaf>,
+    pub checks: BTreeMap<String, Leaf>,
+    pub apps: BTreeMap<String, Leaf>,
+    pub formatter: Option<Leaf>,
+    pub nixos_configurations: BTreeMap<String, Leaf>,
+    pub darwin_configurations: BTreeMap<String, Leaf>,
+    pub home_configurations: BTreeMap<String, Leaf>,
+    pub nixos_modules: BTreeMap<String, Leaf>,
+    pub docker_images: BTreeMap<String, Leaf>,
+    pub overlays: BTreeMap<String, Leaf>,
+    pub templates: BTreeMap<String, Leaf>,
+    pub schemas: BTreeMap<String, Leaf>,
     /// Other unrecognized keys.
     pub other: Option<BTreeMap<String, FlakeOutputs>>,
-    // TODO: Add nixosModules, nixosConfigurations, darwinModules, etc.
 }
 
 impl FlakeSchema {
@@ -35,8 +41,8 @@ impl FlakeSchema {
     /// as is (in [FlakeSchema::other]).
     pub fn from(output: &FlakeOutputs, system: &System) -> Self {
         let output: &mut FlakeOutputs = &mut output.clone();
-        let pop_tree = |output: &mut FlakeOutputs, ks: &[&str]| -> BTreeMap<String, Val> {
-            let mut f = || -> Option<BTreeMap<String, Val>> {
+        let pop_tree = |output: &mut FlakeOutputs, ks: &[&str]| -> BTreeMap<String, Leaf> {
+            let mut f = || -> Option<BTreeMap<String, Leaf>> {
                 let out = output.pop(ks)?;
                 let outs = out.as_attrset()?;
                 let r = outs
@@ -52,14 +58,21 @@ impl FlakeSchema {
             output.pop(ks);
             mr.unwrap_or(BTreeMap::new())
         };
-        let pop_per_system_tree = |output: &mut FlakeOutputs, k: &str| -> BTreeMap<String, Val> {
-            pop_tree(output, &[k, system.as_ref()])
+        let pop_per_system_tree = |output: &mut FlakeOutputs, k: &str| -> BTreeMap<String, Leaf> {
+            pop_tree(
+                output,
+                &[k, "output", "children", system.as_ref(), "children"],
+            )
         };
-        let pop_leaf_type = |output: &mut FlakeOutputs, k: &str| -> Option<Val> {
-            let leaf = output.pop(&[k, system.as_ref()])?.as_leaf()?.clone();
+        let pop_leaf_type = |output: &mut FlakeOutputs, k: &str| -> Option<Leaf> {
+            let leaf = output
+                .pop(&[k, "output", "children", system.as_ref()])?
+                .as_leaf()?
+                .clone();
             output.pop(&[k]);
             Some(leaf)
         };
+
         FlakeSchema {
             system: system.clone(),
             packages: pop_per_system_tree(output, "packages"),
@@ -68,7 +81,17 @@ impl FlakeSchema {
             checks: pop_per_system_tree(output, "checks"),
             apps: pop_per_system_tree(output, "apps"),
             formatter: pop_leaf_type(output, "formatter"),
-            nixos_configurations: pop_tree(output, &["nixosConfigurations"]),
+            nixos_configurations: pop_tree(output, &["nixosConfigurations", "output", "children"]),
+            darwin_configurations: pop_tree(
+                output,
+                &["darwinConfigurations", "output", "children"],
+            ),
+            home_configurations: pop_tree(output, &["homeConfigurations", "output", "children"]),
+            nixos_modules: pop_tree(output, &["nixosModules", "output", "children"]),
+            docker_images: pop_tree(output, &["dockerImages", "output", "children"]),
+            overlays: pop_tree(output, &["overlays", "output", "children"]),
+            templates: pop_tree(output, &["templates", "output", "children"]),
+            schemas: pop_tree(output, &["schemas", "output", "children"]),
             other: (*output).as_attrset().cloned(),
         }
     }

crates/omnix-cli/Cargo.toml

@@ -24,6 +24,7 @@ tabled = { workspace = true }
 tokio = { workspace = true }
 tracing = { workspace = true }
 clap_complete = { workspace = true }
+serde_json = { workspace = true }
 
 [dev-dependencies]
 anyhow = { workspace = true }