Add Deploy routing peers to a Kubernetes cluster guide (#151)

* Add Deploy routing peers to a Kubernetes cluster guide

* adjust images width

Author: mlsmaycon

public/docs-static/img/how-to-guides/k8s-add-access-control-policy.png

@@ -60,6 +60,7 @@ export const docsNavigation = [
             { title: 'Running NetBird on FaaS', href: '/how-to/netbird-on-faas' },
             { title: 'Delete your NetBird account', href: '/how-to/delete-account' },
             { title: 'Manage access with posture checks', href: '/how-to/manage-posture-checks' },
+            { title: 'Deploy routing peers to Kubernetes', href: '/how-to/routing-peers-and-kubernetes' },
             { title: 'Report bugs and issues', href: '/how-to/report-bug-issues' },
             { title: 'Troubleshooting client issues', href: '/how-to/troubleshooting-client' },
             { title: 'Examples', href: '/how-to/examples' },

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@@ -0,0 +1,130 @@
+import {Note} from "@/components/mdx";
+
+# Deploy routing peers to a Kubernetes cluster
+This guide provides instructions on how to use NetBird agent within a Kubernetes cluster to establish secure, peer-to-peer
+networking between your Kubernetes pods and external services or other clusters.
+
+## Prerequisites
+- Access to a Kubernetes cluster
+- Kubernetes CLI (kubectl) installed and configured
+- Access to the NetBird management dashboard
+
+## Use Case Scenario
+Imagine you're running a multi-cloud Kubernetes environment where your application components are distributed across
+different cloud providers, including on-premise Kubernetes clusters. Your goal is to securely access your kubernetes services
+from hosts running on a Hetzner without exposing them to the public internet.
+
+## Step-by-Step guide
+### Step 1: Create a setup key
+Navigate to Setup Keys in the NetBird management dashboard and click on "Create setup key".
+
+Choose a name, e.g. `Kubernetes routing peers`, mark the key as `reusable` and enable `Ephemeral peers`. This option is
+ideal for stateless workloads like containers, where peers that are offline for over 10 minutes are automatically removed.
+
+Create or add group called `kubernetes-routers` to the `Auto-assigned groups` list. This designation can be adjusted to
+suit your needs.
+
+See the screenshot below for reference:
+<p>
+    <img src="/docs-static/img/how-to-guides/k8s-create-setup-key.png" alt="k8s-create-setup-key" width="400" className="imagewrapper"/>
+</p>
+
+With your setup key created, note it down for the next steps.
+
+### Step 2: Add a network route
+Navigate to Network Routes in the NetBird management dashboard and click on `Add Route`.
+
+Set your kubernetes pod range as the destination network, and select the `Peer group` option, choosing the
+"kubernetes-routers" group. This configuration allows for scaling pods as necessary within your Kubernetes cluster.
+
+Set the distribution group to `hetzner-servers`. This group is used to distribute the route to all servers in the group.
+
+See the screenshot below for reference:
+<p>
+    <img src="/docs-static/img/how-to-guides/k8s-add-network-route.png" alt="k8s-add-network-route" width="400" className="imagewrapper"/>
+</p>
+
+Click on Name & Description to give your route a name and description. Then click on `Add Route` to save your changes.
+<p>
+    <img src="/docs-static/img/how-to-guides/k8s-name-network-route.png" alt="k8s-name-network-route" width="400" className="imagewrapper"/>
+</p>
+
+### Step 3: Create an access control policy
+Navigate to Access Control Policies in the NetBird management dashboard and click on `Add Policy`.
+
+Set the source group to `hetzner-servers` and the destination group to `kubernetes-routers`. This configuration allows
+the Hetzner servers to access the kubernetes pods.
+<p>
+    <img src="/docs-static/img/how-to-guides/k8s-add-access-control-policy.png" alt="k8s-add-access-control-policy" width="400" className="imagewrapper"/>
+</p>
+
+Click on Name & Description to give your policy a name and description. Then click on `Add Policy` to save your changes.
+<p>
+    <img src="/docs-static/img/how-to-guides/k8s-name-access-control-policy.png" alt="k8s-name-access-control-policy" width="400" className="imagewrapper"/>
+</p>
+
+### Step 4: Deploy the NetBird agent
+You can deploy the NetBird agent using a daemon set or a deployment. Below is an example of a deployment configuration with 3 replicas.
+
+```yaml
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: netbird
+  namespace: default
+spec:
+  replicas: 3
+  selector:
+    matchLabels:
+      app: netbird
+  template:
+    metadata:
+      labels:
+        app: netbird
+    spec:
+      containers:
+        - name: netbird
+          image: netbirdio/netbird:latest
+          env:
+            - name: NB_SETUP_KEY
+              value: "0000000000-0000-0000-0000-0000000000" # replace with your setup key
+            - name: NB_HOSTNAME
+              value: "netbird-k8s-router" # name that will appear in the management UI
+            - name: NB_LOG_LEVEL
+              value: "info"
+          securityContext:
+            capabilities:
+              add:
+                - NET_ADMIN
+                - SYS_RESOURCE
+                - SYS_ADMIN
+```
+
+Edit your deployment.yml file, incorporating the setup key into the relevant sections.
+
+Apply the updated deployment file to your Kubernetes cluster using the following command:
+```shell
+kubectl apply -f deployment.yml
+```
+
+<Note>
+    In this example the setup key is passed as an environment variable. You should use a secret to pass the setup key.
+</Note>
+
+### Step 5: Verify the deployment
+After deploying the NetBird agent, you can verify that the agent is running by checking the logs of the pods.
+
+```shell
+kubectl logs -l app=netbird
+```
+
+You can also verify that the agent is connected to the NetBird management dashboard by checking the dashboard.
+<p>
+    <img src="/docs-static/img/how-to-guides/k8s-netbird-agent-connected.png" alt="k8s-netbird-agent-connected" width="800" className="imagewrapper"/>
+</p>
+
+## Conclusion
+By following these steps, you've successfully integrated Netbird within your Kubernetes cluster, enabling secure,
+peer-to-peer networking between your Kubernetes pods and external services. This setup is particularly beneficial for
+hybrid, multi-cloud environments and remote access, ensuring seamless connectivity and security across your infrastructure.