feat: added instructions to enable IPv6 networking on application ser…

…vers (#617)

* feat: added IPv6 private networking instructions

---------

Co-authored-by: Brody Over <10548119+brody192@users.noreply.github.com>

src/docs/guides/fixing-common-errors.md

@@ -93,22 +93,23 @@ async function bootstrap() {
 #### Node / Next
 
 Next needs an additional flag to listen on `PORT`:
+
 ```bash
 next start --port ${PORT-3000}
 ```
 
 #### Python / Gunicorn
 
 `gunicorn` listens on `0.0.0.0` and the `PORT` environment variable by default:
+
 ```bash
 gunicorn main:app
 ```
 
-There is no additional configuration necessary.
-
 #### Python / Uvicorn
 
 `uvicorn` needs additional configuration flags to listen on `0.0.0.0` and `PORT`:
+
 ```bash
 uvicorn main:app --host 0.0.0.0 --port $PORT
 ```
@@ -139,4 +140,4 @@ When an HTTP client encounters a 301 Moved Permanently redirect, the client will
 
 ### Solution
 
-Fortunately, the solution is simple: Ensure you are using HTTPS when calling your Railway-hosted services.
+Fortunately, the solution is simple: Ensure you are using HTTPS when calling your Railway-hosted services.

src/docs/guides/private-networking.md

@@ -17,9 +17,13 @@ To communicate over the private network, there are some specific things to know
 
 ### Listen on IPv6
 
-Since the private network is an IPv6 network, applications that will receive requests over the private network must be configured to listen on IPv6.  On most web frameworks, you can do this via `::` and specifying the port(s) to which you want to bind.
+Since the private network is an IPv6 only network, applications that will receive requests over the private network must be configured to listen on IPv6. On most web frameworks, you can do this by binding to the host `::`.
 
-For example - 
+Some examples are below -
+
+#### Node / Express
+
+Listen on `::` to bind to both IPv4 and IPv6.
 
 ```javascript
 const port = process.env.PORT || 3000;
@@ -29,6 +33,64 @@ app.listen(port, '::', () => {
 });
 ```
 
+#### Node / Nest
+
+Listen on `::` to bind to both IPv4 and IPv6.
+
+```javascript
+const port = process.env.PORT || 3000;
+
+async function bootstrap() {
+  await app.listen(port, '::');
+}
+```
+
+#### Node / Next
+
+Update your start command to bind to both IPv4 and IPv6.
+
+```bash
+next start --hostname :: --port ${PORT-3000}
+```
+
+Or if you are using a custom server, set `hostname` to `::` in the configuration object passed to the `next()` function.
+
+```javascript
+const port = process.env.PORT || 3000;
+
+const app = next({
+  // ...
+  hostname: '::',
+  port: port
+});
+```
+
+If neither of these options are viable, you can set a `HOSTNAME` [service variable](/guides/variables#service-variables) with the value `::` to listen on both IPv4 and IPv6.
+
+#### Python / Gunicorn
+
+Update your start command to bind to both IPv4 and IPv6.
+
+```bash
+gunicorn app:app --bind [::]:${PORT-3000}
+```
+
+#### Python / Hypercorn
+
+Update your start command to bind to both IPv4 and IPv6.
+
+```bash
+hypercorn app:app --bind [::]:${PORT-3000}
+```
+
+#### Python / Uvicorn
+
+Update your start command to bind to IPv6.
+
+```bash
+uvicorn app:app --host :: --port ${PORT-3000}
+```
+
 **Note:** If your application needs to be accessible over both private and public networks, your application server must support dual stack binding. Most servers handle this automatically when listening on `::`, but some, like Uvicorn, do not.
 
 ### Use Internal Hostname and Port