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docs/develop/deploy/kubernetes/k3s.md

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+### Integrating WasmEdge with k3s
+
+This guide will help you integrate WasmEdge with k3s, a lightweight Kubernetes distribution for edge computing. Follow the steps below to set up and deploy WasmEdge applications on k3s.
+
+#### Prerequisites
+- A machine with Linux (preferably Ubuntu)
+- Docker installed
+- `k3s` installed
+- `kubectl` command-line tool installed
+- `crun` container runtime installed
+
+#### Step 1: Install k3s
+
+First, install k3s on your machine. You can do this by running the following command:
+
+```sh
+curl -sfL https://get.k3s.io | sh -
+```
+
+This command installs k3s and starts it automatically. To check the status of k3s, run:
+
+```sh
+sudo systemctl status k3s
+```
+
+#### Step 2: Install containerd and crun-wasmedge
+
+WasmEdge requires the `crun` runtime to run WebAssembly applications. Follow these steps to install and configure `containerd` and `crun-wasmedge`.
+
+1. **Install containerd**:
+
+```sh
+sudo apt-get update
+sudo apt-get install -y containerd
+```
+
+2. **Install crun**:
+
+```sh
+sudo apt-get install -y crun
+```
+
+3. **Install WasmEdge**:
+
+Follow the installation instructions from the [WasmEdge documentation](https://wasmedge.org/docs/start/install). For example:
+
+```sh
+curl -sSf https://raw.githubusercontent.com/WasmEdge/WasmEdge/master/utils/install.sh | sudo bash
+```
+
+4. **Configure containerd to use crun with WasmEdge**:
+
+Edit the `config.toml` file for containerd to enable crun as the runtime handler for WasmEdge. This file is typically located at `/etc/containerd/config.toml`.
+
+Add or modify the following lines:
+
+```toml
+[plugins]
+ [plugins.cri.containerd]
+ [plugins.cri.containerd.runtimes]
+ [plugins.cri.containerd.runtimes.crun-wasmedge]
+ runtime_type = "io.containerd.runc.v2"
+ [plugins.cri.containerd.runtimes.crun-wasmedge.options]
+ BinaryName = "crun"
+ SystemdCgroup = true
+```
+
+Restart `containerd` to apply the changes:
+
+```sh
+sudo systemctl restart containerd
+```
+
+#### Step 3: Configure k3s to use containerd with crun-wasmedge
+
+Edit the k3s service configuration to use the configured containerd runtime. Typically, the configuration file is located at `/etc/systemd/system/k3s.service` or `/etc/systemd/system/k3s.service.d/k3s.conf`.
+
+Add the following environment variable to the service configuration:
+
+```ini
+[Service]
+Environment="CONTAINERD_RUNTIME_HANDLER=crun-wasmedge"
+```
+
+Reload the systemd configuration and restart k3s:
+
+```sh
+sudo systemctl daemon-reload
+sudo systemctl restart k3s
+```
+
+#### Step 4: Deploy a WasmEdge application on k3s
+
+Create a Kubernetes deployment YAML file for your WasmEdge application. For example, `wasmedge-deployment.yaml`:
+
+```yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+ name: wasmedge-demo
+spec:
+ replicas: 1
+ selector:
+ matchLabels:
+ app: wasmedge-demo
+ template:
+ metadata:
+ labels:
+ app: wasmedge-demo
+ spec:
+ containers:
+ - name: wasmedge-demo
+ image: your-wasmedge-image:latest
+ command: ["your-wasmedge-command"]
+ resources:
+ limits:
+ memory: "128Mi"
+ cpu: "500m"
+ ports:
+ - containerPort: 8080
+```
+
+Apply the deployment file using `kubectl`:
+
+```sh
+kubectl apply -f wasmedge-deployment.yaml
+```
+
+Check the status of your deployment:
+
+```sh
+kubectl get pods
+```
+
+#### Step 5: Access your WasmEdge application
+
+Expose your WasmEdge application using a Kubernetes service. Create a service YAML file, e.g., `wasmedge-service.yaml`:
+
+```yaml
+apiVersion: v1
+kind: Service
+metadata:
+ name: wasmedge-service
+spec:
+ selector:
+ app: wasmedge-demo
+ ports:
+ - protocol: TCP
+ port: 80
+ targetPort: 8080
+ type: LoadBalancer
+```
+
+Apply the service file:
+
+```sh
+kubectl apply -f wasmedge-service.yaml
+```
+
+Retrieve the external IP address of the service:
+
+```sh
+kubectl get svc wasmedge-service
+```
+
+You can now access your WasmEdge application via the external IP address.
+
+#### Conclusion
+
+You have successfully integrated WasmEdge with k3s and deployed a WebAssembly application. You can now build and deploy more WasmEdge applications on your k3s cluster.