From d55df2967005a9d77275ba747c424df052c6fa41 Mon Sep 17 00:00:00 2001
From: chimurai <655241+chimurai@users.noreply.github.com>
Date: Sat, 23 Apr 2022 22:55:02 +0200
Subject: [PATCH] fix(sse): fix sse when backend restarts

---
 .../default/debug-proxy-errors-plugin.ts      | 30 ++++++++++++++-----
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/src/plugins/default/debug-proxy-errors-plugin.ts b/src/plugins/default/debug-proxy-errors-plugin.ts
index 5bab5fc7..6af70c48 100644
--- a/src/plugins/default/debug-proxy-errors-plugin.ts
+++ b/src/plugins/default/debug-proxy-errors-plugin.ts
@@ -7,7 +7,7 @@ const debug = Debug.extend('debug-proxy-errors-plugin');
  * Subscribe to {@link https://www.npmjs.com/package/http-proxy#listening-for-proxy-events http-proxy error events} to prevent server from crashing.
  * Errors are logged with {@link https://www.npmjs.com/package/debug debug} library.
  */
-export const debugProxyErrorsPlugin: Plugin = (proxyServer): void => {
+export const debugProxyErrorsPlugin: Plugin = (proxyServer, options): void => {
   /**
    * http-proxy doesn't handle any errors by default (https://github.com/http-party/node-http-proxy#listening-for-proxy-events)
    * Prevent server from crashing when http-proxy errors (uncaught errors)
@@ -22,18 +22,34 @@ export const debugProxyErrorsPlugin: Plugin = (proxyServer): void => {
     });
   });
 
-  /**
-   * Fix SSE close events
-   * @link https://github.com/chimurai/http-proxy-middleware/issues/678
-   * @link https://github.com/http-party/node-http-proxy/issues/1520#issue-877626125
-   */
   proxyServer.on('proxyRes', (proxyRes, req, res) => {
+    /**
+     * Fix SSE close events
+     * @link https://github.com/chimurai/http-proxy-middleware/issues/678
+     * @link https://github.com/http-party/node-http-proxy/issues/1520#issue-877626125
+     */
     res.on('close', () => {
       if (!res.writableEnded) {
-        debug('Destroying proxyRes in proxyRes close event');
+        debug('res close event received, destroying proxyRes');
         proxyRes.destroy();
       }
     });
+
+    /**
+     * Fix SSE when backend closes/restarts
+     * @link https://github.com/chimurai/http-proxy-middleware/discussions/765
+     */
+    proxyRes.on('close', () => {
+      // don't destroy res when using it in response interceptor
+      if (options.selfHandleResponse) {
+        return;
+      }
+
+      if (!res.writableEnded) {
+        debug('proxyRes close event received, destroying res');
+        res.destroy();
+      }
+    });
   });
 
   /**