Rename _tapp-address to _dstack-app-address

Author: kvinwang

README.md

@@ -251,7 +251,7 @@ Now, I want to use my custom domain `tapp-nginx.kvin.wang` to access the Tapp. I
 
 Where
 
-`_tapp-address.tapp-nginx.kvin.wang` means configuring the tapp destination address of domain `tapp-nginx.kvin.wang`.
+`_dstack-app-address.tapp-nginx.kvin.wang` means configuring the tapp destination address of domain `tapp-nginx.kvin.wang`.
 
 The TXT record value `3327603e03f5bd1f830812ca4a789277fc31f577:8043` means that requests sent to `tapp-nginx.kvin.wang` will be processed by Tapp `3327603e03f5bd1f830812ca4a789277fc31f577` on port `8043`
 

gateway/gateway.toml

@@ -52,6 +52,7 @@ buffer_size = 8192
 # number of hosts to try to connect to
 connect_top_n = 3
 localhost_enabled = false
+app_address_ns_prefix = "_dstack-app-address"
 
 [core.proxy.timeouts]
 # Timeout for establishing a connection to the target app.

gateway/src/config.rs

@@ -59,6 +59,7 @@ pub struct ProxyConfig {
     pub buffer_size: usize,
     pub connect_top_n: usize,
     pub localhost_enabled: bool,
+    pub app_address_ns_prefix: String,
 }
 
 #[derive(Debug, Clone, Deserialize)]

gateway/src/proxy/tls_passthough.rs

@@ -29,8 +29,8 @@ impl TappAddress {
 }
 
 /// resolve tapp address by sni
-async fn resolve_tapp_address(sni: &str) -> Result<TappAddress> {
-    let txt_domain = format!("_tapp-address.{sni}");
+async fn resolve_tapp_address(prefix: &str, sni: &str) -> Result<TappAddress> {
+    let txt_domain = format!("{prefix}.{sni}");
     let resolver = hickory_resolver::AsyncResolver::tokio_from_system_conf()
         .context("failed to create dns resolver")?;
     let lookup = resolver
@@ -51,7 +51,7 @@ pub(crate) async fn proxy_with_sni(
     buffer: Vec<u8>,
     sni: &str,
 ) -> Result<()> {
-    let tapp_addr = resolve_tapp_address(sni)
+    let tapp_addr = resolve_tapp_address(&state.config.proxy.app_address_ns_prefix, sni)
         .await
         .context("failed to resolve tapp address")?;
     debug!("target address is {}:{}", tapp_addr.app_id, tapp_addr.port);
@@ -120,10 +120,12 @@ mod tests {
 
     #[tokio::test]
     async fn test_resolve_tapp_address() {
-        let tapp_addr =
-            resolve_tapp_address("3327603e03f5bd1f830812ca4a789277fc31f577.app.kvin.wang")
-                .await
-                .unwrap();
+        let tapp_addr = resolve_tapp_address(
+            "_dstack-app-address",
+            "3327603e03f5bd1f830812ca4a789277fc31f577.app.kvin.wang",
+        )
+        .await
+        .unwrap();
         assert_eq!(tapp_addr.app_id, "3327603e03f5bd1f830812ca4a789277fc31f577");
         assert_eq!(tapp_addr.port, 8090);
     }