health: Recognize om.health from flake.nix

crates/nix_health/src/lib.rs

@@ -63,12 +63,16 @@ impl NixHealth {
     /// Fallback to using the default health check config if the flake doesn't
     /// override it.
     pub async fn from_flake(url: &FlakeUrl) -> Result<Self, nix_rs::command::NixCmdError> {
-        nix_eval_attr_json(
-            &NixCmd::default(),
-            &url.with_fully_qualified_root_attr("nix-health"),
-            true,
-        )
-        .await
+        let cmd = NixCmd::default();
+        let v = nix_eval_attr_json(&cmd, &url.with_fully_qualified_root_attr("om.health")).await?;
+        match v {
+            Some(v) => Ok(v),
+            None => {
+                let v = nix_eval_attr_json(&cmd, &url.with_fully_qualified_root_attr("nix-health"))
+                    .await?;
+                Ok(v.unwrap_or_default())
+            }
+        }
     }
 
     /// Run all checks and collect the results

crates/nix_rs/CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## Unreleased
+
+- **eval**
+  - `nix_eval_attr_json`: No longer takes `default_if_missing`; instead (always) returns `None` if attribute is missing.
+
 ## [0.5.0](https://github.com/juspay/nix-rs/compare/0.4.0...0.5.0) (2024-06-05)
 
 ### Features

crates/nix_rs/src/flake/eval.rs

@@ -4,25 +4,20 @@ use super::url::FlakeUrl;
 
 /// Run `nix eval <url> --json` and parse its JSON
 ///
-/// If the flake does not output the given attribute, return the [Default]
-/// value of `T`.
-pub async fn nix_eval_attr_json<T>(
-    cmd: &NixCmd,
-    url: &FlakeUrl,
-    default_if_missing: bool,
-) -> Result<T, NixCmdError>
+/// If the attribute is missing, return None.
+pub async fn nix_eval_attr_json<T>(cmd: &NixCmd, url: &FlakeUrl) -> Result<Option<T>, NixCmdError>
 where
     T: Default + serde::de::DeserializeOwned,
 {
     let result = cmd
         .run_with_args_expecting_json(&["eval", url.0.as_str(), "--json"])
         .await;
     match result {
-        Err(err) if default_if_missing && error_is_missing_attribute(&err) => {
-            // The 'nixci' flake output attr is missing. User wants the default config.
-            Ok(T::default())
+        Ok(v) => Ok(Some(v)),
+        Err(err) if error_is_missing_attribute(&err) => {
+            Ok(None) // Attr is missing
         }
-        r => r,
+        Err(err) => Err(err),
     }
 }
 

crates/omnix-cli/src/command/health.rs

@@ -4,7 +4,8 @@ use nix_rs::flake::url::FlakeUrl;
 
 #[derive(Parser, Debug)]
 pub struct HealthConfig {
-    /// Include health checks defined in the given flake
+    /// Use `om.health` configuration from the given flake
+    #[arg(name = "FLAKE")]
     pub flake_url: Option<FlakeUrl>,
 
     /// Dump the config schema of the health checks (useful when adding them to
@@ -19,8 +20,6 @@ impl HealthConfig {
             tracing::info!("{}", NixHealth::schema()?);
             return Ok(());
         }
-        // TODO: Setup logging (unify `crates/nix_health/src/logging.rs` and `crates/omnix/src/logging.rs`)
-        // TODO: `om.health` config?
         let checks = run_checks_with(self.flake_url.clone()).await?;
         let exit_code = NixHealth::print_report_returning_exit_code(&checks);
         if exit_code != 0 {

crates/omnix-cli/src/command/mod.rs

@@ -16,7 +16,7 @@ pub enum Command {
     /// Build all flake outputs (run CI locally)
     CI(ci::CIConfig),
 
-    /// Show Nix's health
+    /// Display the health of your system environment as suited for Nix
     Health(health::HealthConfig),
 }
 

flake.nix

@@ -26,8 +26,9 @@
         ./crates/nix_health/module/flake-module.nix
       ];
 
-      flake = {
-        nix-health.default = {
+      # omnix configuration
+      flake.om = {
+        health.default = {
           nix-version.min-required = "2.16.0";
           # We don't use a Nix cache yet
           # caches.required = [ "https://cache.juspay.dev" ];