check and merge config from toml and env

crates/cdk-mintd/example.config.toml

@@ -36,7 +36,7 @@ enabled = false
 #[prometheus]
 #enabled = true
 #address = "127.0.0.1"
-#port = 9090
+#port = 9000
 # 
 [info.http_cache]
 # memory or redis

crates/cdk-mintd/src/config.rs

@@ -47,6 +47,7 @@ pub struct LoggingConfig {
 }
 
 #[derive(Clone, Serialize, Deserialize)]
+#[serde(default)]
 pub struct Info {
     pub url: String,
     pub listen_host: String,
@@ -175,6 +176,7 @@ impl std::str::FromStr for LnBackend {
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(default)]
 pub struct Ln {
     pub ln_backend: LnBackend,
     pub invoice_description: Option<String>,
@@ -199,6 +201,7 @@ impl Default for Ln {
 
 #[cfg(feature = "lnbits")]
 #[derive(Clone, Serialize, Deserialize)]
+#[serde(default)]
 pub struct LNbits {
     pub admin_api_key: String,
     pub invoice_api_key: String,
@@ -237,6 +240,7 @@ impl Default for LNbits {
 
 #[cfg(feature = "cln")]
 #[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(default)]
 pub struct Cln {
     pub rpc_path: PathBuf,
     #[serde(default = "default_cln_bolt12")]
@@ -269,6 +273,7 @@ fn default_cln_bolt12() -> bool {
 
 #[cfg(feature = "lnd")]
 #[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(default)]
 pub struct Lnd {
     pub address: String,
     pub cert_file: PathBuf,
@@ -294,6 +299,7 @@ impl Default for Lnd {
 
 #[cfg(feature = "ldk-node")]
 #[derive(Clone, Serialize, Deserialize)]
+#[serde(default)]
 pub struct LdkNode {
     /// Fee percentage (e.g., 0.02 for 2%)
     #[serde(default = "default_ldk_fee_percent")]
@@ -437,6 +443,7 @@ fn default_keyset_version() -> String {
 
 #[cfg(feature = "fakewallet")]
 #[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(default)]
 pub struct FakeWallet {
     pub supported_units: Vec<CurrencyUnit>,
     pub fee_percent: f32,
@@ -487,6 +494,7 @@ fn default_max_delay_time() -> u64 {
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq)]
+#[serde(default)]
 pub struct GrpcProcessor {
     #[serde(default)]
     pub supported_units: Vec<CurrencyUnit>,
@@ -538,17 +546,20 @@ impl std::str::FromStr for DatabaseEngine {
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, Default)]
+#[serde(default)]
 pub struct Database {
     pub engine: DatabaseEngine,
     pub postgres: Option<PostgresConfig>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, Default)]
+#[serde(default)]
 pub struct AuthDatabase {
     pub postgres: Option<PostgresAuthConfig>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(default)]
 pub struct PostgresAuthConfig {
     pub url: String,
     pub tls_mode: Option<String>,
@@ -568,6 +579,7 @@ impl Default for PostgresAuthConfig {
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(default)]
 pub struct PostgresConfig {
     pub url: String,
     pub tls_mode: Option<String>,
@@ -609,6 +621,7 @@ impl std::str::FromStr for AuthType {
 }
 
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
+#[serde(default)]
 pub struct Auth {
     #[serde(default)]
     pub auth_enabled: bool,
@@ -644,6 +657,7 @@ fn default_blind() -> AuthType {
 
 /// CDK settings, derived from `config.toml`
 #[derive(Debug, Clone, Serialize, Deserialize, Default)]
+#[serde(default)]
 pub struct Settings {
     pub info: Info,
     pub mint_info: MintInfo,
@@ -668,11 +682,13 @@ pub struct Settings {
     pub mint_management_rpc: Option<MintManagementRpc>,
     pub auth: Option<Auth>,
     #[cfg(feature = "prometheus")]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub prometheus: Option<Prometheus>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, Default)]
 #[cfg(feature = "prometheus")]
+#[serde(default)]
 pub struct Prometheus {
     pub enabled: bool,
     pub address: Option<String>,
@@ -708,6 +724,7 @@ fn default_max_outputs() -> usize {
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, Default)]
+#[serde(default)]
 pub struct MintInfo {
     /// name of the mint and should be recognizable
     pub name: String,
@@ -731,6 +748,7 @@ pub struct MintInfo {
 
 #[cfg(feature = "management-rpc")]
 #[derive(Debug, Clone, Serialize, Deserialize, Default)]
+#[serde(default)]
 pub struct MintManagementRpc {
     /// When this is set to `true` the mint use the config file for the initial set up on first start.
     /// Changes to the `[mint_info]` after this **MUST** be made via the RPC changes to the config file or env vars will be ignored.
@@ -741,23 +759,30 @@ pub struct MintManagementRpc {
 }
 
 impl Settings {
+    pub fn try_new<P>(config_file_name: Option<P>) -> Result<Self, ConfigError>
+    where
+        P: Into<PathBuf>,
+    {
+        let default_settings = Self::default();
+        Self::new_from_default(&default_settings, config_file_name)
+    }
+
+    /// Loads settings from defaults and an optional config file.
+    ///
+    /// Prefer [`Self::try_new`] in any code path that can surface a recoverable
+    /// config error; this constructor exists for callers that want a hard fail.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the config file cannot be read or deserialized. Unlike earlier
+    /// versions, this never silently falls back to defaults — silent fallback
+    /// hid real misconfiguration.
     #[must_use]
     pub fn new<P>(config_file_name: Option<P>) -> Self
     where
         P: Into<PathBuf>,
     {
-        let default_settings = Self::default();
-        // attempt to construct settings with file
-        let from_file = Self::new_from_default(&default_settings, config_file_name);
-        match from_file {
-            Ok(f) => f,
-            Err(e) => {
-                tracing::error!(
-                    "Error reading config file, falling back to defaults. Error: {e:?}"
-                );
-                default_settings
-            }
-        }
+        Self::try_new(config_file_name).unwrap_or_else(|e| panic!("Error reading config file: {e}"))
     }
 
     fn new_from_default<P>(
@@ -865,6 +890,8 @@ mod tests {
     /// This test runs sequentially for all enabled backends to avoid env var interference.
     #[test]
     fn test_env_var_only_config_all_backends() {
+        let _env_lock = crate::test_utils::env_lock();
+
         // Run each backend test sequentially
         #[cfg(feature = "lnd")]
         test_lnd_env_config();
@@ -918,7 +945,7 @@ max_melt = 500000
         env::set_var(crate::env_vars::ENV_LND_RESERVE_FEE_MIN, "4");
 
         // Load settings and apply environment variables (same as production code)
-        let mut settings = Settings::new(Some(&config_path));
+        let mut settings = Settings::try_new(Some(&config_path)).expect("Failed to load config");
         settings.from_env().expect("Failed to apply env vars");
 
         // Verify that settings were populated from env vars
@@ -975,7 +1002,7 @@ max_melt = 500000
         env::set_var(crate::env_vars::ENV_CLN_RESERVE_FEE_MIN, "4");
 
         // Load settings and apply environment variables (same as production code)
-        let mut settings = Settings::new(Some(&config_path));
+        let mut settings = Settings::try_new(Some(&config_path)).expect("Failed to load config");
         settings.from_env().expect("Failed to apply env vars");
 
         // Verify that settings were populated from env vars
@@ -1033,7 +1060,7 @@ max_melt = 500000
         env::set_var(crate::env_vars::ENV_LNBITS_RESERVE_FEE_MIN, "5");
 
         // Load settings and apply environment variables (same as production code)
-        let mut settings = Settings::new(Some(&config_path));
+        let mut settings = Settings::try_new(Some(&config_path)).expect("Failed to load config");
         settings.from_env().expect("Failed to apply env vars");
 
         // Verify that settings were populated from env vars
@@ -1087,7 +1114,7 @@ max_melt = 500000
         env::set_var(crate::env_vars::ENV_FAKE_WALLET_MAX_DELAY, "5");
 
         // Load settings and apply environment variables (same as production code)
-        let mut settings = Settings::new(Some(&config_path));
+        let mut settings = Settings::try_new(Some(&config_path)).expect("Failed to load config");
         settings.from_env().expect("Failed to apply env vars");
 
         // Verify that settings were populated from env vars
@@ -1141,7 +1168,7 @@ max_melt = 500000
         env::set_var(crate::env_vars::ENV_GRPC_PROCESSOR_PORT, "50051");
 
         // Load settings and apply environment variables (same as production code)
-        let mut settings = Settings::new(Some(&config_path));
+        let mut settings = Settings::try_new(Some(&config_path)).expect("Failed to load config");
         settings.from_env().expect("Failed to apply env vars");
 
         // Verify that settings were populated from env vars
@@ -1199,7 +1226,7 @@ max_melt = 500000
         );
 
         // Load settings and apply environment variables (same as production code)
-        let mut settings = Settings::new(Some(&config_path));
+        let mut settings = Settings::try_new(Some(&config_path)).expect("Failed to load config");
         settings.from_env().expect("Failed to apply env vars");
 
         // Verify that settings were populated from env vars

crates/cdk-mintd/src/env_vars/mod.rs

@@ -146,7 +146,7 @@ impl Settings {
                 self.grpc_processor =
                     Some(self.grpc_processor.clone().unwrap_or_default().from_env());
             }
-            LnBackend::None => bail!("Ln backend must be set"),
+            LnBackend::None => {}
             #[allow(unreachable_patterns)]
             _ => bail!("Selected Ln backend is not enabled in this build"),
         }