https://wasmedge.org/docs/assets/js/664bb007.408a8438.js

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1function m(e){let{components:t,...a}=e;return(0,s.kt)(u,(0,n.Z)({},d,a,{components:t,mdxType:"MDXLayout"}),(0,s.kt)("h1",{id:"k3s"},"K3s"),(0,s.kt)("p",null,(0,s.kt)("a",{parentName:"p",href:"https://k3s.io/"},"K3s")," is a lightweight, certified Kubernetes distribution designed for resource-constrained environments such as edge, IoT, and CI/CD. It bundles containerd as the default container runtime and can automatically detect WebAssembly runtimes like WasmEdge."),(0,s.kt)("admonition",{type:"note"},(0,s.kt)("p",{parentName:"admonition"},"This guide is based on containerd + runwasi (containerd-shim-wasmedge).")),(0,s.kt)("h2",{id:"prerequisites"},"Prerequisites"),(0,s.kt)("ul",null,(0,s.kt)("li",{parentName:"ul"},"A Linux machine (x86_64 or aarch64) with systemd"),(0,s.kt)("li",{parentName:"ul"},"Root or sudo access")),(0,s.kt)("h2",{id:"install-wasmedge"},"Install WasmEdge"),(0,s.kt)("p",null,"Use the ",(0,s.kt)("a",{parentName:"p",href:"/docs/start/install"},"simple install script")," to install WasmEdge on your node."),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},"curl -sSf https://raw.githubusercontent.com/WasmEdge/WasmEdge/master/utils/install.sh | bash\n")),(0,s.kt)("h2",{id:"install-the-containerd-shim-wasmedge"},"Install the containerd-shim-wasmedge"),(0,s.kt)("p",null,"K3s looks for the ",(0,s.kt)("inlineCode",{parentName:"p"},"containerd-shim-wasmedge-v1")," binary in the system PATH. You can install it from a pre-built release binary or build it from source."),(0,s.kt)("h3",{id:"option-a-pre-built-binary"},"Option A: Pre-built binary"),(0,s.kt)("p",null,"Download the latest release from the ",(0,s.kt)("a",{parentName:"p",href:"https://github.com/containerd/runwasi/releases"},"runwasi releases page")," and install it."),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},"# Detect architecture and download the appropriate binary\nARCH=$(uname -m) # x86_64 or aarch64\nwget https://github.com/containerd/runwasi/releases/download/containerd-shim-wasmedge%2Fv0.6.0/containerd-shim-wasmedge-${ARCH}-linux-musl.tar.gz\ntar xzf containerd-shim-wasmedge-${ARCH}-linux-musl.tar.gz\nsudo install -m 755 containerd-shim-wasmedge-v1 /usr/local/bin/\n")),(0,s.kt)("h3",{id:"option-b-build-from-source"},"Option B: Build from source"),(0,s.kt)("p",null,"Make sure you have ",(0,s.kt)("a",{parentName:"p",href:"https://www.rust-lang.org/tools/install"},"Rust")," installed, then build the shim from the ",(0,s.kt)("a",{parentName:"p",href:"https://github.com/containerd/runwasi"},"runwasi")," project."),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},'git clone https://github.com/containerd/runwasi.git\ncd runwasi\n./scripts/setup-linux.sh\nmake build-wasmedge\nINSTALL="sudo install" LN="sudo ln -sf" make install-wasmedge\n')),(0,s.kt)("h2",{id:"install-and-start-k3s"},"Install and start K3s"),(0,s.kt)("p",null,"Install K3s after the shim binary is in place, so that K3s can detect the WasmEdge runtime at startup."),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},"curl -sfL https://get.k3s.io | sh -\n")),(0,s.kt)("p",null,"K3s will automatically detect ",(0,s.kt)("inlineCode",{parentName:"p"},"containerd-shim-wasmedge-v1")," in the system PATH and create a corresponding Kubernetes ",(0,s.kt)("inlineCode",{parentName:"p"},"RuntimeClass")," named ",(0,s.kt)("inlineCode",{parentName:"p"},"wasmedge"),"."),(0,s.kt)("p",null,"Verify that K3s is running and the RuntimeClass exists:"),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},"sudo kubectl get nodes\nsudo kubectl get runtimeclass\n")),(0,s.kt)("p",null,"Expected output:"),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},"$ sudo kubectl get nodes\nNAME     STATUS   ROLES           AGE   VERSION\nubuntu   Ready    control-plane   45s   v1.34.6+k3s1\n\n$ sudo kubectl get runtimeclass\nNAME                  HANDLER               AGE\ncrun                  crun                  45s\nlunatic               lunatic               45s\nnvidia                nvidia                45s\nnvidia-experimental   nvidia-experimental   45s\nslight                slight                45s\nspin                  spin                  45s\nwasmedge              wasmedge              45s\nwasmer                wasmer                45s\nwasmtime              wasmtime              45s\nwws                   wws                   45s\n")),(0,s.kt)("p",null,"Make sure ",(0,s.kt)("inlineCode",{parentName:"p"},"wasmedge")," is in the list."),(0,s.kt)("admonition",{type:"note"},(0,s.kt)("p",{parentName:"admonition"},"If the ",(0,s.kt)("inlineCode",{parentName:"p"},"wasmedge")," RuntimeClass does not appear, make sure the ",(0,s.kt)("inlineCode",{parentName:"p"},"containerd-shim-wasmedge-v1")," binary is in a directory listed in the K3s service's PATH (e.g., ",(0,s.kt)("inlineCode",{parentName:"p"},"/usr/local/bin"),"), then restart K3s with ",(0,s.kt)("inlineCode",{parentName:"p"},"sudo systemctl restart k3s"),".")),(0,s.kt)("h2",{id:"run-a-simple-webassembly-app"},"Run a simple WebAssembly app"),(0,s.kt)("p",null,(0,s.kt)("a",{parentName:"p",href:"https://github.com/second-state/wasmedge-containers-examples/blob/main/simple_wasi_app.md"},"A separate article")," explains how to compile, package, and publish a simple WebAssembly WASI program as a container image to Docker Hub. Run the WebAssembly-based image from Docker Hub in the K3s cluster as follows."),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},'sudo kubectl run --restart=Never wasi-demo \\\n  --image=wasmedge/example-wasi:latest \\\n  --overrides=\'{"kind":"Pod","apiVersion":"v1","spec":{"runtimeClassName":"wasmedge"}}\' \\\n  -- /wasi_example_main.wasm 50000000\n')),(0,s.kt)("p",null,"Check the pod status and view the output:"),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},"sudo kubectl get pod wasi-demo\nsudo kubectl logs wasi-demo\n")),(0,s.kt)("p",null,"The output from the containerized application is printed into the console."),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},"$ sudo kubectl get pod wasi-demo\nNAME        READY   STATUS      RESTARTS   AGE\nwasi-demo   0/1     Completed   0          7s\n\n$ sudo kubectl logs wasi-demo\nRandom number: -817406905\nRandom bytes: [7, 7, 147, 202, 106, 102, 198, 6, 42, 39, 198, 92, 59, 247, 54, 99, 249, 117, 113, 

1143, 240, 85, 226, 102, 44, 165, 66, 251, 220, 107, 106, 70, 168, 144, 114, 113, 77, 132, 114, 33, 155, 254, 169, 196, 218, 119, 171, 145, 106, 36, 205, 130, 43, 208, 152, 127, 60, 57, 26, 160, 178, 75, 3, 215, 98, 32, 223, 67, 176, 35, 182, 141, 2, 190, 15, 72, 167, 44, 46, 148, 240, 1, 110, 148, 19, 134, 182, 21, 127, 141, 106, 65, 27, 84, 121, 217, 171, 36, 88, 47, 197, 96, 193, 102, 143, 105, 67, 77, 40, 187, 40, 151, 60, 140, 238, 143, 8, 89, 129, 117, 103, 157, 102, 34, 65, 5, 195, 246]\nPrinted from wasi: This is from a main function\nThis is from a main function\nThe env vars are as follows.\nThe args are as follows.\n/wasi_example_main.wasm\n50000000\nFile content is This is in a file\n")),(0,s.kt)("p",null,"Clean up the pod after verifying:"),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},"sudo kubectl delete pod wasi-demo\n")),(0,s.kt)("h2",{id:"run-a-webassembly-based-http-service"},"Run a WebAssembly-based HTTP service"),(0,s.kt)("p",null,(0,s.kt)("a",{parentName:"p",href:"https://github.com/second-state/wasmedge-containers-examples/blob/main/http_server_wasi_app.md"},"A separate article")," explains how to compile, package, and publish a simple WebAssembly HTTP service application as a container image to Docker Hub. Create a deployment using a YAML file:"),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-yaml"},"apiVersion: apps/v1\nkind: Deployment\nmetadata:\n  name: http-server\nspec:\n  replicas: 1\n  selector:\n    matchLabels:\n      app: http-server\n  template:\n    metadata:\n      labels:\n        app: http-server\n    spec:\n      runtimeClassName: wasmedge\n      containers:\n        - name: http-server\n          image: wasmedge/example-wasi-http:latest\n          ports:\n            - containerPort: 1234\n              protocol: TCP\n---\napiVersion: v1\nkind: Service\nmetadata:\n  name: http-server\nspec:\n  type: NodePort\n  selector:\n    app: http-server\n  ports:\n    - port: 1234\n      targetPort: 1234\n")),(0,s.kt)("p",null,"Save the above as ",(0,s.kt)("inlineCode",{parentName:"p"},"k3s-http-server.yaml")," and apply it:"),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},"sudo kubectl apply -f k3s-http-server.yaml\n")),(0,s.kt)("p",null,"Wait for the pod to be ready, then get the NodePort:"),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},"sudo kubectl get svc http-server\n")),(0,s.kt)("p",null,"Access the HTTP service using the NodePort:"),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},'curl -d "name=WasmEdge" -X POST http://localhost:<NodePort>\necho: name=WasmEdge\n')),(0,s.kt)("p",null,"Clean up the deployment and service after verifying:"),(0,s.kt)("pre",null,(0,s.kt)("code",{parentName:"pre",className:"language-bash"},"sudo kubectl delete -f k3s-http-server.yaml\n")),(0,s.kt)("p",null,"That's it!"))}m.isMDXComponent=!0}}]);