> Markdown version of [Hostname Guidelines](https://vaadin.com/docs/v24/control-center/application-deployment/hostname-guidelines). Section index: [llms.txt](https://vaadin.com/docs/v24/control-center/llms.txt)

# Hostname Guidelines

When deploying applications to a Kubernetes cluster, it’s important to choose proper hostnames for your applications and services. This page provides guidelines for choosing hostnames for your Control Center applications and services.

## <a id="hostname-necessity"></a>Hostname Necessity

A hostname has two requirements: external access; and service communication. Regarding external access, the hostname acts as the application’s URL and makes it accessible from outside the cluster (e.g., via a browser or API calls). As for service communication, other services or microservices may need to communicate with your Vaadin application via this hostname.

A valid hostname must resolve to an IP address that can be accessed from the browser or external services.

### <a id="cloud-environments"></a>Cloud Environments

If your Kubernetes cluster is hosted on a cloud platform (e.g., Google Kubernetes Engine, Amazon EKS, Azure AKS), you can add a DNS record that points to the cluster’s public IP.

To do this, get the public IP address of your service from your cloud provider’s dashboard. Then add a DNS record (e.g., `app.mydomain.com`) pointing to this public IP. For example, you might use:

```
https://app.mydomain.com
```

Make sure your firewall rules or security settings allow external traffic to this IP address on the appropriate ports.

### <a id="local-development-testing"></a>Local Development & Testing

If you’re working with a local Kubernetes cluster (e.g., Minikube, Docker Desktop), you can use a local hostname and configure your operating system’s `hosts` file to resolve it to the loopback address.

The next two sub-sections provide the steps for configuring the `hosts` file depending on your operating system. Be sure to use a consistent hostname throughout your development environment to avoid a misconfiguration.

Whichever system you use, after editing the file, you can access your application locally by using the hostname, `http://app.local`.

#### <a id="linux-macos"></a>Linux & macOS

When using a Unix based system like Linux or macOS, you’ll need to open the `hosts` file with administrative privileges like so:

```bash
sudo nano /etc/hosts
```

There you’ll have to add the following line to map `app.local` to your loopback address:

```plain
127.0.0.1   app.local
```

#### <a id="windows"></a>Windows

If you’re using a Windows system, you’ll instead need to start Notepad as an administrator. Using it, open the `hosts` file located at `C:\Windows\System32\drivers\etc\hosts`.

Add the following line to that file:

```plain
127.0.0.1   app.local
```