WEB: Resolve opt-in decoy hostnames during config preparation #929

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

src/healthcheck.rs

@@ -8,13 +8,17 @@ use crate::config::ProxyConfig;
 
 const HEALTHCHECK_RESPONSE_MAX_BYTES: u64 = 64 * 1024;
 
+/// API health contract selected by the standalone healthcheck command.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub(crate) enum HealthcheckMode {
+    /// Require a responsive API process.
     Liveness,
+    /// Require the active runtime to report readiness.
     Ready,
 }
 
 impl HealthcheckMode {
+    /// Parses the supported command-line healthcheck modes.
     pub(crate) fn from_cli_arg(value: &str) -> Option<Self> {
         match value {
             "liveness" => Some(Self::Liveness),
@@ -31,6 +35,7 @@ impl HealthcheckMode {
     }
 }
 
+/// Runs the bounded API healthcheck without preparing a new proxy generation.
 pub(crate) fn run(config_path: &str, mode: HealthcheckMode) -> i32 {
     match run_inner(config_path, mode) {
         Ok(()) => 0,
@@ -42,8 +47,9 @@ pub(crate) fn run(config_path: &str, mode: HealthcheckMode) -> i32 {
 }
 
 fn run_inner(config_path: &str, mode: HealthcheckMode) -> Result<(), String> {
-    let config =
-        ProxyConfig::load(config_path).map_err(|error| format!("config load failed: {error}"))?;
+    let config = ProxyConfig::parse_source(config_path)
+        .map_err(|error| format!("config load failed: {error}"))?
+        .config;
     let api_cfg = &config.server.api;
     if !api_cfg.enabled {
         return Ok(());
@@ -229,4 +235,26 @@ mod tests {
 
         assert!(read_response_bounded(&mut payload.as_slice()).is_err());
     }
+
+    #[test]
+    fn decoy_dns_healthcheck_reads_source_without_resolution() {
+        let directory = tempfile::tempdir().unwrap();
+        let path = directory.path().join("config.toml");
+        std::fs::write(
+            &path,
+            r#"
+[server.api]
+enabled = false
+[[web.vhosts]]
+host = "proxy.example.com"
+public_addr = "203.0.113.10:443"
+[web.vhosts.decoy]
+mode = "http_upstream"
+upstream = "http://unresolvable.example.invalid:8080"
+resolve = "startup"
+"#,
+        )
+        .unwrap();
+        super::run_inner(path.to_str().unwrap(), HealthcheckMode::Liveness).unwrap();
+    }
 }