Initialize config defaults in separate function

src/server/config.rs

@@ -1,6 +1,7 @@
 use std::net::{IpAddr, Ipv4Addr, SocketAddr};
 use std::path::PathBuf;
 
+use config::{ConfigBuilder, ConfigError, builder::DefaultState};
 use serde::Deserialize;
 
 /// Enable secure cookies by default only in release mode
@@ -203,11 +204,22 @@ pub struct Config {
 
 impl Config {
     /// Parse configuration from the expected files and environment variables
-    pub fn from_env() -> Result<Self, config::ConfigError> {
+    pub fn from_env() -> Result<Self, ConfigError> {
         use config::{Environment, File};
 
         let pkg_name = env!("CARGO_PKG_NAME");
 
+        Self::defaults()?
+            .add_source(File::with_name(&format!("/etc/{pkg_name}/config")).required(false))
+            .add_source(File::with_name(&format!("/etc/{pkg_name}")).required(false))
+            .add_source(File::with_name("config").required(false))
+            .add_source(Environment::with_prefix(pkg_name).separator("_"))
+            .build()?
+            .try_deserialize()
+    }
+
+    /// Generate a `config::ConfigBuilder` from default values
+    fn defaults() -> Result<ConfigBuilder<DefaultState>, ConfigError> {
         config::Config::builder()
             .set_default(
                 "server.port",
@@ -221,13 +233,7 @@ impl Config {
             )?
             .set_default("auth.open_signup", false)?
             .set_default("auth.cookies_secure", DEFAULT_COOKIES_SECURE)?
-            .set_default("server.public_path", default_public_dir())?
+            .set_default("server.public_path", default_public_dir())
-            .add_source(File::with_name(&format!("/etc/{pkg_name}/config")).required(false))
-            .add_source(File::with_name(&format!("/etc/{pkg_name}")).required(false))
-            .add_source(File::with_name("config").required(false))
-            .add_source(Environment::with_prefix(pkg_name).separator("_"))
-            .build()?
-            .try_deserialize()
     }
 }