Can I bind to a specific host? How is the host option passed through?

Question

RepoPilot · Accepted Answer

Yes, you can bind to a specific host using the `host` option in the `getPort()` function.

**How to use it:**

According to [index.d.ts:L57-L62], the `host` option is defined as:

> The host on which port resolution should be performed. Can be either an IPv4 or IPv6 address.
>
> By default, it checks availability on all local addresses defined in [OS network interfaces](https://nodejs.org/api/os.html#os_os_networkinterfaces). If this option is set, it will only check the given host.

**Examples from tests:**

The test suite shows practical usage. For instance, [test.js:L48-L55] demonstrates passing an IPv4 host:

```js
test('preferred port given IPv4 host', async t => {
	const desiredPort = 8081;
	const port = await getPort({
		port: desiredPort,
		host: '0.0.0.0',
	});

t.is(port, desiredPort);
});
```

**How it's passed through:**

Looking at the Options type definition in [index.d.ts:L3-L65], the `host` option is part of the `Options` object that gets passed to `getPort()`. Additionally, the Options type uses `& Omit<ListenOptions, 'port'>` at line 64, which means the `host` option is ultimately passed through to Node.js's underlying `net.Server.listen()` method (since `ListenOptions` comes from that API).

FOLLOW_UPS:
- What happens when host is not specified?
- Can I use IPv6 addresses with the host option?
- How does reserve option interact with host?