allow generic settings

foundations/examples/Cargo.toml

@@ -12,6 +12,10 @@ path = "src/simple.rs"
 name = "http"
 path = "src/http.rs"
 
+[[example]]
+name = "generics"
+path = "src/generics.rs"
+
 [dependencies]
 scuffle-foundations = { path = "../" }
 tracing = "0.1"

foundations/examples/src/generics.rs

@@ -0,0 +1,20 @@
+use scuffle_foundations::settings::{auto_settings, Settings};
+
+#[auto_settings]
+pub struct BaseSettings<S: Settings + Default> {
+    #[serde(flatten)]
+    /// The internal settings.
+    external: S,
+}
+
+#[auto_settings]
+pub struct ExtraSettings {
+    /// An extra setting.
+    pub extra: bool,
+    /// Another extra setting.
+    pub another: bool,
+}
+
+fn main() {
+    println!("{}", BaseSettings::<ExtraSettings>::default().to_yaml_string().unwrap());
+}

foundations/examples/src/http.rs

@@ -11,15 +11,15 @@ use scuffle_foundations::runtime::spawn;
 use scuffle_foundations::settings::cli::Matches;
 use scuffle_foundations::telementry::opentelemetry::OpenTelemetrySpanExt;
 use scuffle_foundations::telementry::settings::TelementrySettings;
-use scuffle_foundations::{settings::settings, wrapped, BootstrapResult};
+use scuffle_foundations::{settings::auto_settings, wrapped, BootstrapResult};
 use std::convert::Infallible;
 use std::net::SocketAddr;
 use std::net::TcpListener as StdTcpListener;
 use tokio::net::{TcpListener, TcpStream};
 
 type Body = http_body_util::Full<Bytes>;
 
-#[settings]
+#[auto_settings]
 #[serde(default)]
 struct Config {
     telemetry: TelementrySettings,

foundations/examples/src/simple.rs

@@ -1,6 +1,6 @@
 use scuffle_foundations::{
     bootstrap::{bootstrap, Bootstrap, RuntimeSettings},
-    settings::{cli::Matches, settings},
+    settings::{cli::Matches, auto_settings},
     telementry::{metrics::metrics, settings::TelementrySettings},
 };
 
@@ -24,7 +24,7 @@ mod http_server {
     pub fn requests_failed_total(endpoint_name: &Arc<String>, status_code: u16) -> Counter;
 }
 
-#[settings]
+#[auto_settings]
 pub struct HttpServerSettings {
     /// Telementry Settings
     telementry: TelementrySettings,

foundations/macros/src/settings/types/field_ty.rs

@@ -3,7 +3,7 @@ use syn::{LitStr, Meta};
 use crate::helpers::parse_docs;
 
 use super::{
-    serde::{parse_default_fn, Name, RenameAll},
+    serde::{parse_default_fn, serde_flatten, Name, RenameAll},
     Args,
 };
 
@@ -14,6 +14,7 @@ pub struct Field {
     pub default_fn: Option<proc_macro2::TokenStream>,
     pub args: FieldArgs,
     pub item: syn::Field,
+    pub flatten: bool,
 }
 
 impl Field {
@@ -27,6 +28,7 @@ impl Field {
             docs: parse_docs(&item.attrs),
             default_fn: parse_default_fn(&item.attrs)?,
             args: FieldArgs::parse(&item.attrs)?,
+            flatten: serde_flatten(&item.attrs)?,
             item,
         })
     }

foundations/macros/src/settings/types/serde.rs

@@ -163,6 +163,13 @@ pub fn parse_default_fn(attrs: &[syn::Attribute]) -> syn::Result<Option<proc_mac
     })
 }
 
+pub fn serde_flatten(attrs: &[syn::Attribute]) -> syn::Result<bool> {
+    parse_serde_attrs(attrs, false, |state, meta| match meta {
+        Meta::Path(meta) if meta.is_ident("flatten") => *state = true,
+        _ => {}
+    })
+}
+
 fn parse_serde_attrs<T>(
     attr: &[syn::Attribute],
     state: T,

foundations/macros/src/settings/types/struct_ty.rs

@@ -100,7 +100,7 @@ impl Struct {
                 })
                 .collect::<Vec<_>>();
 
-            let insert = if docs.is_empty() {
+            let insert = if docs.is_empty() || field.flatten {
                 quote::quote! {}
             } else {
                 quote::quote! {
@@ -111,10 +111,18 @@ impl Struct {
             let name = &name.serialize;
             let ident = field.item.ident.as_ref().unwrap();
 
+            let name_push = if field.flatten {
+                quote::quote! {}
+            } else {
+                quote::quote! {
+                    parent_key.push(::std::borrow::Cow::Borrowed(#name));
+                }
+            };
+
             quote::quote! {
                 {
                     let mut parent_key = parent_key.to_vec();
-                    parent_key.push(::std::borrow::Cow::Borrowed(#name));
+                    #name_push
                     (&&&&#crate_path::settings::Wrapped(&self.#ident)).add_docs(&parent_key, docs);
                     #insert
                 }

foundations/macros/src/settings/types/variant_ty.rs

@@ -91,15 +91,15 @@ impl Variant {
                 })
                 .collect::<Vec<_>>();
 
-            let insert = if docs.is_empty() {
+            let insert = if docs.is_empty() || field.flatten {
                 quote::quote! {}
             } else {
                 quote::quote! {
                     docs.insert(parent_key, ::std::borrow::Cow::Borrowed(&[#(#docs),*]));
                 }
             };
 
-            let name_push = if self.fields.len() == 1 && field.name.is_none() {
+            let name_push = if (self.fields.len() == 1 && field.name.is_none()) || field.flatten {
                 quote::quote! {}
             } else {
                 let name = field

foundations/src/settings/mod.rs

@@ -7,7 +7,7 @@ use serde_yaml::Value;
 pub mod cli;
 
 #[cfg(feature = "macros")]
-pub use scuffle_foundations_macros::{auto_settings as settings, Settings};
+pub use scuffle_foundations_macros::{auto_settings, Settings};
 
 #[derive(Debug, Clone)]
 pub struct SettingsParser<S> {

foundations/src/settings/traits.rs

@@ -153,3 +153,5 @@ where
         (**self.0).add_docs(parent_key, docs);
     }
 }
+
+impl Settings for () {}

foundations/src/telementry/settings.rs

@@ -13,7 +13,7 @@ use opentelemetry_sdk::Resource;
 #[cfg(feature = "logging")]
 use tracing_subscriber::fmt::time::{ChronoLocal, ChronoUtc};
 
-#[crate::settings::settings(crate_path = "crate")]
+#[crate::settings::auto_settings(crate_path = "crate")]
 pub struct TelementrySettings {
     /// Settings for metric exporting.
     pub metrics: MetricsSettings,
@@ -30,7 +30,7 @@ pub struct TelementrySettings {
 }
 
 #[cfg(feature = "metrics")]
-#[crate::settings::settings(crate_path = "crate")]
+#[crate::settings::auto_settings(crate_path = "crate")]
 pub struct MetricsSettings {
     /// Whether to enable metrics.
     #[settings(default = true)]
@@ -40,7 +40,7 @@ pub struct MetricsSettings {
 }
 
 #[cfg(feature = "opentelemetry")]
-#[crate::settings::settings(crate_path = "crate")]
+#[crate::settings::auto_settings(crate_path = "crate")]
 #[serde(default)]
 pub struct OpentelemetrySettings {
     /// Whether to enable opentelemetry span exporting.
@@ -98,7 +98,7 @@ pub struct OpentelemetrySettings {
 }
 
 #[cfg(feature = "opentelemetry")]
-#[crate::settings::settings(crate_path = "crate")]
+#[crate::settings::auto_settings(crate_path = "crate")]
 #[serde(default)]
 pub struct OpentelemetrySettingsLogging {
     #[settings(default = OpentelemetrySettingsLoggingLevel::Warn)]
@@ -110,7 +110,7 @@ pub struct OpentelemetrySettingsLogging {
 }
 
 #[cfg(feature = "opentelemetry")]
-#[crate::settings::settings(crate_path = "crate")]
+#[crate::settings::auto_settings(crate_path = "crate")]
 #[serde(rename_all = "lowercase")]
 pub enum OpentelemetrySettingsLoggingLevel {
     /// Error level logging.
@@ -129,7 +129,7 @@ pub enum OpentelemetrySettingsLoggingLevel {
 }
 
 #[cfg(feature = "opentelemetry")]
-#[crate::settings::settings(crate_path = "crate")]
+#[crate::settings::auto_settings(crate_path = "crate")]
 #[serde(rename_all = "lowercase")]
 pub enum OpentelemetrySettingsExportMethod {
     #[settings(default)]
@@ -140,7 +140,7 @@ pub enum OpentelemetrySettingsExportMethod {
 }
 
 #[cfg(feature = "opentelemetry")]
-#[crate::settings::settings(crate_path = "crate")]
+#[crate::settings::auto_settings(crate_path = "crate")]
 #[serde(rename_all = "lowercase")]
 pub enum OpentelemetrySettingsSampler {
     /// Always sample all spans.
@@ -174,7 +174,7 @@ fn default_true() -> bool {
 }
 
 #[cfg(feature = "logging")]
-#[crate::settings::settings(crate_path = "crate")]
+#[crate::settings::auto_settings(crate_path = "crate")]
 #[serde(default)]
 pub struct LoggingSettings {
     /// Whether to enable logging.
@@ -209,7 +209,7 @@ pub struct LoggingSettings {
 }
 
 #[cfg(feature = "logging")]
-#[crate::settings::settings(crate_path = "crate")]
+#[crate::settings::auto_settings(crate_path = "crate")]
 #[serde(rename_all = "lowercase")]
 pub enum LoggingSettingsTimestamps {
     /// Show timestamps in logs in the local timezone.
@@ -222,7 +222,7 @@ pub enum LoggingSettingsTimestamps {
 }
 
 #[cfg(feature = "logging")]
-#[crate::settings::settings(crate_path = "crate")]
+#[crate::settings::auto_settings(crate_path = "crate")]
 #[serde(rename_all = "lowercase")]
 pub enum LoggingSettingsFormat {
     #[settings(default)]
@@ -240,7 +240,7 @@ pub enum LoggingSettingsFormat {
     any(feature = "pprof-cpu", feature = "pprof-heap", feature = "metrics",),
     feature = "telemetry-server"
 ))]
-#[crate::settings::settings(crate_path = "crate")]
+#[crate::settings::auto_settings(crate_path = "crate")]
 #[serde(default)]
 pub struct ServerSettings {
     /// Whether to enable the server.