Fix demo development inside a dev container (#21261)

.devcontainer/devcontainer.json

@@ -8,6 +8,7 @@
   "postCreateCommand": "sudo apt update && sudo apt upgrade -y && sudo apt install -y libpcap-dev",
   "postStartCommand": "script/bootstrap",
   "containerEnv": {
+    "DEV_CONTAINER": "1",
     "WORKSPACE_DIRECTORY": "${containerWorkspaceFolder}"
   },
   "customizations": {

build-scripts/env.cjs

@@ -32,4 +32,7 @@ module.exports = {
     }
     return version[1];
   },
+  isDevContainer() {
+    return process.env.DEV_CONTAINER === "1";
+  },
 };

build-scripts/gulp/webpack.js

@@ -40,8 +40,12 @@ const runDevServer = async ({
   compiler,
   contentBase,
   port,
-  listenHost = "localhost",
+  listenHost = undefined,
 }) => {
+  if (listenHost === undefined) {
+    // For dev container, we need to listen on all hosts
+    listenHost = env.isDevContainer() ? "0.0.0.0" : "localhost";
+  }
   const server = new WebpackDevServer(
     {
       hot: false,