Ensure that every section-level config type has a builder() function.

Cargo.lock

@@ -123,6 +123,7 @@ version = "0.0.1"
 dependencies = [
  "arti-client",
  "config",
+ "derive_builder",
  "once_cell",
  "regex",
  "serde",

crates/arti-client/src/config.rs

@@ -53,6 +53,13 @@ impl Default for ClientAddrConfig {
     }
 }
 
+impl ClientAddrConfig {
+    /// Return a new [`ClientAddrConfigBuilder`].
+    pub fn builder() -> ClientAddrConfigBuilder {
+        ClientAddrConfigBuilder::default()
+    }
+}
+
 /// Configuration for where information should be stored on disk.
 ///
 /// This section is for read/write storage.

crates/arti-config/Cargo.toml

@@ -19,6 +19,7 @@ serde = { version = "1.0.124", features = ["derive"] }
 toml = "0.5.8"
 regex = { version = "1.5.3", default-features = false, features = ["std"] }
 thiserror = "1.0.24"
+derive_builder = "0.10.2"
 
 [dev-dependencies]
 tempfile = "3.2.0"

crates/arti-config/src/options.rs

@@ -4,6 +4,7 @@ use arti_client::config::{
     dir::{DownloadScheduleConfig, NetworkConfig},
     StorageConfig, TorClientConfig,
 };
+use derive_builder::Builder;
 use serde::Deserialize;
 use std::collections::HashMap;
 use tor_config::ConfigBuildError;
@@ -12,9 +13,10 @@ use tor_config::ConfigBuildError;
 pub(crate) const ARTI_DEFAULTS: &str = concat!(include_str!("./arti_defaults.toml"),);
 
 /// Structure to hold our logging configuration options
-#[derive(Deserialize, Debug, Clone)]
+#[derive(Deserialize, Debug, Clone, Builder)]
 #[serde(deny_unknown_fields)]
 #[non_exhaustive] // TODO(nickm) remove public elements when I revise this.
+#[builder(build_fn(error = "ConfigBuildError"))]
 pub struct LoggingConfig {
     /// Filtering directives that determine tracing levels as described at
     /// <https://docs.rs/tracing-subscriber/0.2.20/tracing_subscriber/filter/struct.EnvFilter.html>
@@ -30,9 +32,17 @@ pub struct LoggingConfig {
     pub journald: bool,
 }
 
+impl LoggingConfig {
+    /// Return a new LoggingConfigBuilder
+    pub fn builder() -> LoggingConfigBuilder {
+        LoggingConfigBuilder::default()
+    }
+}
+
 /// Configuration for one or more proxy listeners.
-#[derive(Deserialize, Debug, Clone)]
+#[derive(Deserialize, Debug, Clone, Builder)]
 #[serde(deny_unknown_fields)]
+#[builder(build_fn(error = "ConfigBuildError"))]
 pub struct ProxyConfig {
     /// Port to listen on (at localhost) for incoming SOCKS
     /// connections.
@@ -40,6 +50,11 @@ pub struct ProxyConfig {
 }
 
 impl ProxyConfig {
+    /// Return a new [`ProxyConfigBuilder`].
+    pub fn builder() -> ProxyConfigBuilder {
+        ProxyConfigBuilder::default()
+    }
+
     /// Return the configured SOCKS port for this proxy configuration,
     /// if one is enabled.
     pub fn socks_port(&self) -> Option<u16> {

crates/tor-circmgr/src/config.rs

@@ -45,6 +45,10 @@ fn ipv6_prefix_default() -> u8 {
 }
 
 impl PathConfig {
+    /// Return a new [`PathConfigBuilder`].
+    pub fn builder(&self) -> PathConfigBuilder {
+        PathConfigBuilder::default()
+    }
     /// Return a subnet configuration based on these rules.
     pub fn subnet_config(&self) -> tor_netdir::SubnetConfig {
         tor_netdir::SubnetConfig::new(
@@ -106,6 +110,13 @@ impl Default for CircuitTiming {
     }
 }
 
+impl CircuitTiming {
+    /// Return a new [`CircuitTimingBuilder`]
+    pub fn builder() -> CircuitTimingBuilder {
+        CircuitTimingBuilder::default()
+    }
+}
+
 /// Configuration for a circuit manager.
 ///
 /// This configuration includes information about how to build paths
@@ -128,3 +139,10 @@ pub struct CircMgrConfig {
     #[builder(default)]
     pub(crate) circuit_timing: CircuitTiming,
 }
+
+impl CircMgrConfig {
+    /// Return a new [CircMgrConfigBuiler`].
+    pub fn builder() -> CircMgrConfigBuilder {
+        CircMgrConfigBuilder::default()
+    }
+}