Update page to add a use case

Author: mlsmaycon

src/components/NavigationDocs.jsx

@@ -57,7 +57,7 @@ export const docsNavigation = [
             { title: 'Monitor system and network activity', href: '/how-to/monitor-system-and-network-activity' },
             { title: 'Activity event streaming', href: '/how-to/activity-event-streaming' },
             { title: 'Access NetBird API', href: '/how-to/access-netbird-public-api' },
-            { title: 'Netstack - Cloud functions', href: '/how-to/netstack' },
+            { title: 'Running NetBird on FaaS', href: '/how-to/netbird-on-faas' },
             { title: 'Examples', href: '/how-to/examples' },
             { title: 'CLI', href: '/how-to/cli' },
             { title: 'Delete your NetBird account', href: '/how-to/delete-account' },

src/pages/how-to/netbird-on-faas.mdx

@@ -0,0 +1,64 @@
+
+# Running NetBird on FaaS environments
+
+Function as a Service (FaaS) is a cloud computing model where developers write individual "functions" – small, single-purpose pieces of code – 
+which are then deployed and managed by a cloud provider. This model eliminates the need for developers to manage infrastructure, as the FaaS 
+provider automatically handles the scaling, provisioning, and maintenance of servers. When a specific event triggers a function, the FaaS platform 
+executes it, only charging for the time and resources used during execution. This makes FaaS highly scalable and cost-effective, especially for applications 
+with variable or unpredictable workloads. It's a bit like having an on-demand, auto-scaling computing service, where you only pay for what you use, when you use it.
+
+In FaaS environments, there are significant limitations, especially in terms of accessing the system's root, kernel, 
+and network stack. Developers do not have root or kernel-level access, a restriction critical for maintaining security and stability in a shared cloud infrastructure. 
+This constraint ensures that the actions of one user don't impact the overall system, especially in a multi-tenant setup. Additionally, access to the system's network 
+stack is also limited. This means that tasks like creating WireGuard tunnels, which require more profound system-level network configuration, might not be feasible.
+
+
+NetBird has adapted to the constraints of FaaS environments by leveraging netstack from the gVisor Go package, which is part of [Wireguard-go](https://github.com/netbirdio/wireguard-go), 
+enabling the WireGuard stack to run entirely in userspace. This approach circumvents the typical need for root or kernel-level access, which is often restricted in 
+cloud-based systems to ensure security and stability. Furthermore, NetBird enhances its network capabilities by implementing a SOCKS5 proxy, allowing applications to seamlessly 
+connect to private resources within a NetBird network. This method not only respects the security protocols of FaaS environments but also ensures efficient and secure network 
+connectivity, all without requiring the deep system-level access typically barred in these platforms.
+
+## How to enable netstack mode?
+You can enable the netstack mode for the NetBird client using environment variables:
+
+`NB_USE_NETSTACK_MODE`: Set to true to enable netstack mode. (Default: false)
+`NB_SOCKS5_LISTENER_PORT`: Set the port where the Socks5 proxy listens. (Default: 1080)
+
+<Note>
+    The DNS feature is not supported. You can reach the peers by IP address only.
+</Note>
+
+### Running locally
+```bash
+export NB_USE_NETSTACK_MODE=true
+export NB_SOCKS5_LISTENER_PORT=30000
+netbird up -F
+```
+
+### Docker
+Some container environments can be restricted as well. For example, Docker containers are not allowed to create new VPN interfaces by default. For that reason, you can run a NetBird agent in a standard mode to enable the netstack mode:
+```bash
+docker run --rm --name PEER_NAME --hostname PEER_NAME -d \
+-e NB_SETUP_KEY=<SETUP KEY> -e NB_USE_NETSTACK_MODE=true -e  NB_SOCKS5_LISTENER_PORT=1080 -v netbird-client:/etc/netbird netbirdio/netbird:latest
+```
+This is useful when you want to configure a simple routing peer without adding privileged permissions or linux capabilities.
+
+## How to use the SOCKS5 proxy?
+Once you have the agent running in netstack mode, you need to configure your application to use the SOCKS5 proxy. The following is an example of a python 3 application:
+```python
+import socks
+import socket
+import os
+def Example():
+    socks.set_default_proxy(socks.SOCKS5, "127.0.0.1", int(os.getenv('NB_SOCKS5_LISTENER_PORT', '1080')))
+    socket.socket = socks.socksocket
+    # rest of the code...
+```
+## How to use NetBird in FaaS environments?
+Cloud providers like AWS and Azure, allow you to configure custom runtime environments for their function services, in AWS this is called Lambda Layers, 
+and in Azure, it's called containerized Azure Functions.
+
+There are many ways that you can configure these environments with NetBird's client binary. We have created a simple example using containerized Azure Functions, 
+which you can find [Azure functions python db access example
+](https://github.com/netbirdio/azure-functions-python-db-access).