feat: provide HOST env variable at runtime (#5421)

* feat: provide HOST env variable at runtime

* doc: add change to documentation

* Update documentation according to suggestions

Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>

* fix: empty string is considered as undefined

Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>

.changeset/violet-buckets-repeat.md

@@ -0,0 +1,5 @@
+---
+'@astrojs/node': minor
+---
+
+Allow HOST env variable to be provided at runtime

packages/integrations/node/README.md

@@ -109,6 +109,15 @@ node ./dist/server/entry.mjs
 
 For standalone mode the server handles file servering in addition to the page and API routes.
 
+
+#### Custom host and port
+
+You can override the host and port the standalone server runs on by passing them as environment variables at runtime:
+
+```shell
+HOST=0.0.0.0 PORT=3000 node ./dist/server/entry.mjs
+```
+
 #### HTTPS
 
 By default the standalone server uses HTTP. This works well if you have a proxy server in front of it that does HTTPS. If you need the standalone server to run HTTPS itself you need to provide your SSL key and certificate.

packages/integrations/node/src/standalone.ts

@@ -39,7 +39,8 @@ export default function startServer(app: NodeApp, options: Options) {
 	const { client } = resolvePaths(options);
 	const handler = middleware(app);
 
-	const host = getResolvedHostForHttpServer(options.host);
+	// Allow to provide host value at runtime
+	const host = getResolvedHostForHttpServer(process.env.HOST !== undefined && process.env.HOST !== '' ? process.env.HOST : options.host);
 	const server = createServer(
 		{
 			client,