Gray Action for API by #630

Co-Authored-By: brekotis <93345790+brekotis@users.noreply.github.com>

src/config/hot_reload.rs

@@ -560,6 +560,7 @@ fn warn_non_hot_changes(old: &ProxyConfig, new: &ProxyConfig, non_hot_changed: b
     if old.server.api.enabled != new.server.api.enabled
         || old.server.api.listen != new.server.api.listen
         || old.server.api.whitelist != new.server.api.whitelist
+        || old.server.api.gray_action != new.server.api.gray_action
         || old.server.api.auth_header != new.server.api.auth_header
         || old.server.api.request_body_limit_bytes != new.server.api.request_body_limit_bytes
         || old.server.api.minimal_runtime_enabled != new.server.api.minimal_runtime_enabled

src/config/load.rs

@@ -1492,6 +1492,7 @@ mod tests {
         assert_eq!(cfg.censorship.unknown_sni_action, UnknownSniAction::Drop);
         assert_eq!(cfg.server.api.listen, default_api_listen());
         assert_eq!(cfg.server.api.whitelist, default_api_whitelist());
+        assert_eq!(cfg.server.api.gray_action, ApiGrayAction::Drop);
         assert_eq!(
             cfg.server.api.request_body_limit_bytes,
             default_api_request_body_limit_bytes()
@@ -1662,6 +1663,7 @@ mod tests {
         );
         assert_eq!(server.api.listen, default_api_listen());
         assert_eq!(server.api.whitelist, default_api_whitelist());
+        assert_eq!(server.api.gray_action, ApiGrayAction::Drop);
         assert_eq!(
             server.api.request_body_limit_bytes,
             default_api_request_body_limit_bytes()
@@ -1809,6 +1811,59 @@ mod tests {
         );
     }
 
+    #[test]
+    fn api_gray_action_parses_and_defaults_to_drop() {
+        let cfg_default: ProxyConfig = toml::from_str(
+            r#"
+            [server]
+            [general]
+            [network]
+            [access]
+            "#,
+        )
+        .unwrap();
+        assert_eq!(cfg_default.server.api.gray_action, ApiGrayAction::Drop);
+
+        let cfg_api: ProxyConfig = toml::from_str(
+            r#"
+            [server]
+            [general]
+            [network]
+            [access]
+            [server.api]
+            gray_action = "api"
+            "#,
+        )
+        .unwrap();
+        assert_eq!(cfg_api.server.api.gray_action, ApiGrayAction::Api);
+
+        let cfg_200: ProxyConfig = toml::from_str(
+            r#"
+            [server]
+            [general]
+            [network]
+            [access]
+            [server.api]
+            gray_action = "200"
+            "#,
+        )
+        .unwrap();
+        assert_eq!(cfg_200.server.api.gray_action, ApiGrayAction::Ok200);
+
+        let cfg_drop: ProxyConfig = toml::from_str(
+            r#"
+            [server]
+            [general]
+            [network]
+            [access]
+            [server.api]
+            gray_action = "drop"
+            "#,
+        )
+        .unwrap();
+        assert_eq!(cfg_drop.server.api.gray_action, ApiGrayAction::Drop);
+    }
+
     #[test]
     fn dc_overrides_allow_string_and_array() {
         let toml = r#"

src/config/types.rs

@@ -1183,6 +1183,13 @@ pub struct ApiConfig {
     #[serde(default = "default_api_whitelist")]
     pub whitelist: Vec<IpNetwork>,
 
+    /// Behavior for requests from source IPs outside `whitelist`.
+    /// - `api`: return structured API forbidden response.
+    /// - `200`: return `200 OK` with an empty body.
+    /// - `drop`: close the connection without HTTP response.
+    #[serde(default)]
+    pub gray_action: ApiGrayAction,
+
     /// Optional static value for `Authorization` header validation.
     /// Empty string disables header auth.
     #[serde(default)]
@@ -1227,6 +1234,7 @@ impl Default for ApiConfig {
             enabled: default_true(),
             listen: default_api_listen(),
             whitelist: default_api_whitelist(),
+            gray_action: ApiGrayAction::default(),
             auth_header: String::new(),
             request_body_limit_bytes: default_api_request_body_limit_bytes(),
             minimal_runtime_enabled: default_api_minimal_runtime_enabled(),
@@ -1240,6 +1248,19 @@ impl Default for ApiConfig {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "lowercase")]
+pub enum ApiGrayAction {
+    /// Preserve current API behavior for denied source IPs.
+    Api,
+    /// Mimic a plain web endpoint by returning `200 OK` with an empty body.
+    #[serde(rename = "200")]
+    Ok200,
+    /// Drop connection without HTTP response for denied source IPs.
+    #[default]
+    Drop,
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
 #[serde(rename_all = "lowercase")]
 pub enum ConntrackMode {