10 files changed, 71 insertions, 8 deletions
diff --git a/.changeset/good-teachers-relax.md b/.changeset/good-teachers-relax.md
new file mode 100644
index 000000000..6048804ba
--- /dev/null
+++ b/.changeset/good-teachers-relax.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Add ability to specify hostname in devOptions
diff --git a/packages/astro/src/@types/astro.ts b/packages/astro/src/@types/astro.ts
index 3ff0ceb7e..e57d2db18 100644
--- a/packages/astro/src/@types/astro.ts
+++ b/packages/astro/src/@types/astro.ts
@@ -29,6 +29,7 @@ export interface AstroConfig {
   };
   /** Options for the development server run with `astro dev`. */
   devOptions: {
+    hostname?: string;
     /** The port to run the dev server on. */
     port: number;
     projectRoot?: string;
@@ -42,6 +43,7 @@ export type AstroUserConfig = Omit<AstroConfig, 'buildOptions' | 'devOptions'> &
     sitemap: boolean;
   };
   devOptions: {
+    hostname?: string;
     port?: number;
     projectRoot?: string;
     tailwindConfig?: string;
diff --git a/packages/astro/src/cli.ts b/packages/astro/src/cli.ts
index 6c33f3106..a1628e2ac 100644
--- a/packages/astro/src/cli.ts
+++ b/packages/astro/src/cli.ts
@@ -27,6 +27,7 @@ interface CLIState {
   options: {
     projectRoot?: string;
     sitemap?: boolean;
+    hostname?: string;
     port?: number;
     config?: string;
     reload?: boolean;
@@ -93,6 +94,7 @@ async function printVersion() {
 function mergeCLIFlags(astroConfig: AstroConfig, flags: CLIState['options']) {
   if (typeof flags.sitemap === 'boolean') astroConfig.buildOptions.sitemap = flags.sitemap;
   if (typeof flags.port === 'number') astroConfig.devOptions.port = flags.port;
+  if (typeof flags.hostname === 'string') astroConfig.devOptions.hostname = flags.hostname;
 }
 
 /** Handle `astro run` command */
diff --git a/packages/astro/src/compiler/index.ts b/packages/astro/src/compiler/index.ts
index 329ffccc1..215a80aca 100644
--- a/packages/astro/src/compiler/index.ts
+++ b/packages/astro/src/compiler/index.ts
@@ -107,7 +107,8 @@ interface CompileComponentOptions {
 /** Compiles an Astro component */
 export async function compileComponent(source: string, { compileOptions, filename, projectRoot }: CompileComponentOptions): Promise<CompileResult> {
   const result = await transformFromSource(source, { compileOptions, filename, projectRoot });
-  const site = compileOptions.astroConfig.buildOptions.site || `http://localhost:${compileOptions.astroConfig.devOptions.port}`;
+  const { hostname, port } = compileOptions.astroConfig.devOptions
+  const site = compileOptions.astroConfig.buildOptions.site || `http://${hostname}:${port}`;
 
   // return template
   let moduleJavaScript = `
diff --git a/packages/astro/src/config.ts b/packages/astro/src/config.ts
index 7e2aeec4e..b41d67003 100644
--- a/packages/astro/src/config.ts
+++ b/packages/astro/src/config.ts
@@ -43,6 +43,9 @@ function validateConfig(config: any): void {
   if (typeof config.devOptions?.port !== 'number') {
     throw new Error(`[config] devOptions.port: Expected number, received ${type(config.devOptions?.port)}`);
   }
+  if (typeof config.devOptions?.hostname !== 'string') {
+    throw new Error(`[config] devOptions.hostname: Expected string, received ${type(config.devOptions?.hostname)}`);
+  }
   if (config.devOptions?.tailwindConfig !== undefined && typeof config.devOptions?.tailwindConfig !== 'string') {
     throw new Error(`[config] devOptions.tailwindConfig: Expected string, received ${type(config.devOptions?.tailwindConfig)}`);
   }
@@ -59,6 +62,7 @@ async function configDefaults(userConfig?: any): Promise<any> {
   if (!config.public) config.public = './public';
   if (!config.devOptions) config.devOptions = {};
   if (!config.devOptions.port) config.devOptions.port = await getPort({ port: getPort.makeRange(3000, 3050) });
+  if (!config.devOptions.hostname) config.devOptions.hostname = 'localhost';
   if (!config.buildOptions) config.buildOptions = {};
   if (!config.markdownOptions) config.markdownOptions = {};
   if (typeof config.buildOptions.sitemap === 'undefined') config.buildOptions.sitemap = true;
diff --git a/packages/astro/src/dev.ts b/packages/astro/src/dev.ts
index f85d4dda1..7a0828109 100644
--- a/packages/astro/src/dev.ts
+++ b/packages/astro/src/dev.ts
@@ -9,8 +9,6 @@ import { defaultLogDestination, defaultLogLevel, debug, error, info, parseError
 import { createRuntime } from './runtime.js';
 import { stopTimer } from './build/util.js';
 
-const hostname = '127.0.0.1';
-
 const logging: LogOptions = {
   level: defaultLogLevel,
   dest: defaultLogDestination,
@@ -50,7 +48,8 @@ export default async function dev(astroConfig: AstroConfig) {
         break;
       }
       case 404: {
-        const fullurl = new URL(req.url || '/', astroConfig.buildOptions.site || `http://localhost${astroConfig.devOptions.port}`);
+        const { hostname, port } = astroConfig.devOptions;
+        const fullurl = new URL(req.url || '/', astroConfig.buildOptions.site || `http://${hostname}:${port}`);
         const reqPath = decodeURI(fullurl.pathname);
         error(logging, 'static', 'Not found', reqPath);
         res.statusCode = 404;
@@ -99,7 +98,7 @@ export default async function dev(astroConfig: AstroConfig) {
     }
   });
 
-  const port = astroConfig.devOptions.port;
+  const { hostname, port } = astroConfig.devOptions;
   server
     .listen(port, hostname, () => {
       const endServerTime = performance.now();
diff --git a/packages/astro/src/runtime.ts b/packages/astro/src/runtime.ts
index 2bcc9316b..a1219c3a8 100644
--- a/packages/astro/src/runtime.ts
+++ b/packages/astro/src/runtime.ts
@@ -66,7 +66,7 @@ async function load(config: RuntimeConfig, rawPathname: string | undefined): Pro
   const { logging, snowpackRuntime, snowpack, configManager } = config;
   const { buildOptions, devOptions } = config.astroConfig;
 
-  let origin = buildOptions.site ? new URL(buildOptions.site).origin : `http://localhost:${devOptions.port}`;
+  let origin = buildOptions.site ? new URL(buildOptions.site).origin : `http://${devOptions.hostname}:${devOptions.port}`;
   const fullurl = new URL(rawPathname || '/', origin);
 
   const reqPath = decodeURI(fullurl.pathname);
diff --git a/packages/astro/test/config-hostname.test.js b/packages/astro/test/config-hostname.test.js
new file mode 100644
index 000000000..0458c7536
--- /dev/null
+++ b/packages/astro/test/config-hostname.test.js
@@ -0,0 +1,43 @@
+import { fileURLToPath } from 'url';
+import { suite } from 'uvu';
+import * as assert from 'uvu/assert';
+import { runDevServer } from './helpers.js';
+import { loadConfig } from '#astro/config';
+
+const ConfigPort = suite('Config hostname');
+const MAX_TEST_TIME = 10000; // max time this test suite may take
+
+const root = new URL('./fixtures/config-hostname/', import.meta.url);
+const timers = {};
+
+ConfigPort.before.each(({ __test__ }) => {
+  timers[__test__] = setTimeout(() => {
+    throw new Error(`Test "${__test__}" did not finish within allowed time`);
+  }, MAX_TEST_TIME);
+});
+
+ConfigPort('can be specified in the astro config', async (context) => {
+  const astroConfig = await loadConfig(fileURLToPath(root));
+  assert.equal(astroConfig.devOptions.hostname, '0.0.0.0');
+});
+
+ConfigPort('can be specified via --hostname flag', async (context) => {
+  const args = ['--hostname', '127.0.0.1'];
+  const proc = runDevServer(root, args);
+
+  proc.stdout.setEncoding('utf8');
+  for await (const chunk of proc.stdout) {
+    if (/Local:/.test(chunk)) {
+      assert.ok(/:127.0.0.1/.test(chunk), 'Using the right hostname');
+      break;
+    }
+  }
+
+  proc.kill();
+});
+
+ConfigPort.after.each(({ __test__ }) => {
+  clearTimeout(timers[__test__]);
+});
+
+ConfigPort.run();
diff --git a/packages/astro/test/fixtures/config-hostname/astro.config.mjs b/packages/astro/test/fixtures/config-hostname/astro.config.mjs
new file mode 100644
index 000000000..e1e33ea0a
--- /dev/null
+++ b/packages/astro/test/fixtures/config-hostname/astro.config.mjs
@@ -0,0 +1,6 @@
+
+export default {
+  devOptions: {
+    hostname: '0.0.0.0'
+  }
+}
diff --git a/packages/create-astro/src/config.ts b/packages/create-astro/src/config.ts
index 40e6653a0..31b7acc20 100644
--- a/packages/create-astro/src/config.ts
+++ b/packages/create-astro/src/config.ts
@@ -10,8 +10,9 @@ export const createConfig = ({ renderers }: { renderers: string[] }) => {
     sitemap: true,         // Generate sitemap (set to "false" to disable)
   },
   devOptions: {
-    // port: 3000,         // The port to run the dev server on.
-    // tailwindConfig: '', // Path to tailwind.config.js if used, e.g. './tailwind.config.js'
+    // hostname: 'localhost',  // The hostname to run the dev server on. 
+    // port: 3000,             // The port to run the dev server on.
+    // tailwindConfig: '',     // Path to tailwind.config.js if used, e.g. './tailwind.config.js'
   },`,
     `  renderers: ${JSON.stringify(renderers, undefined, 2)
       .split('\n')