feat: allow configuring Metro bind host (#70)

hannojg · V3RON · web-flow · commit a0f64b1d9e65 · 2026-03-06T19:02:40.000+01:00
Co-authored-by: Szymon Chmal &lt;szymon@chmal.it&gt;
diff --git a/.nx/version-plans/version-plan-1772810670470.md b/.nx/version-plans/version-plan-1772810670470.md
@@ -0,0 +1,5 @@
+---
+__default__: patch
+---
+
+Add a new host option to rn-harness.config for Metro bind host, replacing HARNESS_METRO_BIND_HOST.
diff --git a/packages/bundler-metro/src/factory.ts b/packages/bundler-metro/src/factory.ts
@@ -66,9 +66,15 @@ export const getMetroInstance = async (
     .use('/status', getStatusMiddleware(projectRoot));
 
   const ready = waitForBundler(reporter, abortSignal);
+  const metroBindHost = harnessConfig.host?.trim();
+  if (metroBindHost) {
+    logger.debug(`Binding Metro server to host ${metroBindHost}`);
+  }
+
   const maybeServer = await Metro.runServer(config, {
     waitForBundler: true,
     unstable_extraMiddleware: [middleware],
+    ...(metroBindHost ? { host: metroBindHost } : {}),
   });
 
   // Metro <0.83 returns the server directly, while 0.83+ returns an object with the server as a property.
diff --git a/packages/config/src/types.ts b/packages/config/src/types.ts
@@ -21,6 +21,7 @@ export const ConfigSchema = z
       .min(1, 'App registry component name is required'),
     runners: z.array(RunnerSchema).min(1, 'At least one runner is required'),
     defaultRunner: z.string().optional(),
+    host: z.string().min(1, 'Host is required').optional(),
     webSocketPort: z.number().optional().default(3001),
     bridgeTimeout: z
       .number()
diff --git a/website/src/docs/getting-started/configuration.mdx b/website/src/docs/getting-started/configuration.mdx
@@ -84,6 +84,7 @@ For Expo projects, the `entryPoint` should be set to the path specified in the `
 | `appRegistryComponentName`         | **Required.** Name of the component registered with AppRegistry.              |
 | `runners`                          | **Required.** Array of test runners (at least one required).                  |
 | `defaultRunner`                    | Default runner to use when none specified.                                    |
+| `host`                             | Hostname or IP address to bind the Metro server to (default: Metro default).  |
 | `bridgeTimeout`                    | Bridge timeout in milliseconds (default: `60000`).                            |
 | `bundleStartTimeout`               | Bundle start timeout in milliseconds (default: `15000`).                      |
 | `maxAppRestarts`                   | Maximum number of app restarts when app fails to report ready (default: `2`). |

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +__default__: patch
 +---
++
 +Add a new host option to rn-harness.config for Metro bind host, replacing HARNESS_METRO_BIND_HOST.