From d78658a4821ac63aaa46564385fcdc820ec6c554 Mon Sep 17 00:00:00 2001
From: Ives van Hoorne <ives@codesandbox.io>
Date: Fri, 31 Jan 2025 10:17:38 +0100
Subject: [PATCH 1/2] feat: support __VITE_ADDITIONAL_SERVER_ALLOWED_HOSTS for
 defining allowed hosts

---
 packages/vite/src/node/server/index.ts | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/packages/vite/src/node/server/index.ts b/packages/vite/src/node/server/index.ts
index b3c10bccf92456..3825ec52c4e028 100644
--- a/packages/vite/src/node/server/index.ts
+++ b/packages/vite/src/node/server/index.ts
@@ -1154,6 +1154,17 @@ export function resolveServerOptions(
     )
   }
 
+  if (
+    process.env.__VITE_ADDITIONAL_SERVER_ALLOWED_HOSTS &&
+    Array.isArray(server.allowedHosts)
+  ) {
+    const additionalHosts = process.env.__VITE_ADDITIONAL_SERVER_ALLOWED_HOSTS
+      .split(',')
+      .map((h) => h.trim())
+
+    server.allowedHosts = [...server.allowedHosts, ...additionalHosts]
+  }
+
   return server
 }
 

From fa9ddc8e5da9182b3906b25a06ff9dfee71aaf32 Mon Sep 17 00:00:00 2001
From: Ives van Hoorne <ives@codesandbox.io>
Date: Tue, 4 Feb 2025 20:26:58 +0100
Subject: [PATCH 2/2] process feedback

---
 docs/config/server-options.md          | 4 ++++
 packages/vite/src/node/server/index.ts | 7 ++-----
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/docs/config/server-options.md b/docs/config/server-options.md
index a4031d6828e584..5263690dc28a80 100644
--- a/docs/config/server-options.md
+++ b/docs/config/server-options.md
@@ -56,6 +56,10 @@ If a string starts with `.`, it will allow that hostname without the `.` and all
 If set to `true`, the server is allowed to respond to requests for any hosts.
 This is not recommended as it will be vulnerable to DNS rebinding attacks.
 
+::: details Configure via environment variable
+You can set the environment variable `__VITE_ADDITIONAL_SERVER_ALLOWED_HOSTS` to add an additional allowed host.
+:::
+
 ## server.port
 
 - **Type:** `number`
diff --git a/packages/vite/src/node/server/index.ts b/packages/vite/src/node/server/index.ts
index 3825ec52c4e028..1e4328c5129b98 100644
--- a/packages/vite/src/node/server/index.ts
+++ b/packages/vite/src/node/server/index.ts
@@ -1158,11 +1158,8 @@ export function resolveServerOptions(
     process.env.__VITE_ADDITIONAL_SERVER_ALLOWED_HOSTS &&
     Array.isArray(server.allowedHosts)
   ) {
-    const additionalHosts = process.env.__VITE_ADDITIONAL_SERVER_ALLOWED_HOSTS
-      .split(',')
-      .map((h) => h.trim())
-
-    server.allowedHosts = [...server.allowedHosts, ...additionalHosts]
+    const additionalHost = process.env.__VITE_ADDITIONAL_SERVER_ALLOWED_HOSTS
+    server.allowedHosts = [...server.allowedHosts, additionalHost]
   }
 
   return server