Added docs for Kubernetes+containerd+runwasi setup, updated runwasi setup page (#240)

Signed-off-by: Shivesh Gupta <shiveshanjaligupta@gmail.com>

Author: shiveshcodes

docs/develop/deploy/cri-runtime/containerd.md

@@ -19,7 +19,9 @@ The containerd-shim [runwasi](https://github.com/containerd/runwasi/) project su
 3. Build and install the wasmedge-containerd-shim
 
    ```bash
+   # Reference: https://github.com/containerd/runwasi/blob/main/CONTRIBUTING.md#setting-up-your-local-environment
    cd runwasi
+   ./scripts/setup-linux.sh
    make build-wasmedge
    INSTALL="sudo install" LN="sudo ln -sf" make install-wasmedge
    ```

docs/develop/deploy/kubernetes/kubernetes-containerd-runwasi.md

@@ -4,7 +4,144 @@ sidebar_position: 3
 
 # Kubernetes + Containerd + Runwasi
 
-<!-- prettier-ignore -->
-:::info
-Work in Progress
-:::
+## Quick start
+
+The [GitHub repo](https://github.com/second-state/wasmedge-containers-examples/) contains scripts and GitHub Actions for running our example apps on Kubernetes + containerd + runwasi.
+
+- Simple WebAssembly example [Quick start](https://github.com/second-state/wasmedge-containers-examples/blob/main/kubernetes_containerd/README.md) | [Github Actions](https://github.com/second-state/wasmedge-containers-examples/blob/main/.github/workflows/kubernetes-containerd.yml)
+- WebAssembly-based HTTP service [Quick start](https://github.com/second-state/wasmedge-containers-examples/blob/main/kubernetes_containerd/http_server/README.md) | [Github Actions](https://github.com/second-state/wasmedge-containers-examples/blob/main/.github/workflows/kubernetes-containerd-server.yml)
+
+In the rest of this section, we will explain the steps in detail.
+
+## Prerequisites for this setup
+
+Please ensure that you have completed the following steps before proceeding with this setup.
+
+- Install the latest version of [Wasmedge](../../../start/install.md)
+- Ensure that you have containerd setup following the [instructions here](../../deploy/cri-runtime/containerd-crun.md). 
+- Ensure that you have installed and [setup runwasi](../../deploy/cri-runtime/containerd.md) for containerd-shim-wasmedge
+
+
+
+## Install and start Kubernetes
+
+Run the following commands from a terminal window. It sets up Kubernetes for local development.
+
+```bash
+# Install go
+$ wget https://golang.org/dl/go1.17.1.linux-amd64.tar.gz
+$ sudo rm -rf /usr/local/go
+$ sudo tar -C /usr/local -xzf go1.17.1.linux-amd64.tar.gz
+$ source /home/${USER}/.profile
+
+# Clone k8s
+$ git clone https://github.com/kubernetes/kubernetes.git
+$ cd kubernetes
+$ git checkout v1.22.2
+
+# Install etcd with hack script in k8s
+$ sudo CGROUP_DRIVER=systemd CONTAINER_RUNTIME=remote CONTAINER_RUNTIME_ENDPOINT='unix:///var/run/containerd/containerd.sock' ./hack/install-etcd.sh
+$ export PATH="/home/${USER}/kubernetes/third_party/etcd:${PATH}"
+$ sudo cp third_party/etcd/etcd* /usr/local/bin/
+
+# After run the above command, you can find the following files: /usr/local/bin/etcd  /usr/local/bin/etcdctl  /usr/local/bin/etcdutl
+
+# Build and run k8s with containerd
+$ sudo apt-get install -y build-essential
+$ sudo CGROUP_DRIVER=systemd CONTAINER_RUNTIME=remote CONTAINER_RUNTIME_ENDPOINT='unix:///var/run/containerd/containerd.sock' ./hack/local-up-cluster.sh
+
+... ...
+Local Kubernetes cluster is running. Press Ctrl-C to shut it down.
+```
+
+Do NOT close your terminal window. Kubernetes is running!
+
+
+## Run and test the Kubernetes Cluster
+
+Finally, we can run WebAssembly programs in Kubernetes as containers in pods. In this section, we will start from **another terminal window** and start using the cluster.
+
+```bash
+export KUBERNETES_PROVIDER=local
+
+sudo cluster/kubectl.sh config set-cluster local --server=https://localhost:6443 --certificate-authority=/var/run/kubernetes/server-ca.crt
+sudo cluster/kubectl.sh config set-credentials myself --client-key=/var/run/kubernetes/client-admin.key --client-certificate=/var/run/kubernetes/client-admin.crt
+sudo cluster/kubectl.sh config set-context local --cluster=local --user=myself
+sudo cluster/kubectl.sh config use-context local
+sudo cluster/kubectl.sh
+```
+
+Let's check the status to make sure that the cluster is running.
+
+```bash
+$ sudo cluster/kubectl.sh cluster-info
+
+# Expected output
+Cluster "local" set.
+User "myself" set.
+Context "local" created.
+Switched to context "local".
+Kubernetes control plane is running at https://localhost:6443
+CoreDNS is running at https://localhost:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
+
+To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
+```
+
+## Configure containerd and Kubernetes for Wasmedge Runtime 
+
+Next we will configure containerd to add support for the containerd-shim-wasmedge.
+Please ensure that you have [setup runwasi](../../deploy/cri-runtime/containerd.md) to work with WasmEdge container images.
+```bash
+# Run the following command as root user
+sudo bash -c "containerd config default > /etc/containerd/config.toml"
+echo '[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.wasmedge] runtime_type = "io.containerd.wasmedge.v1"' | sudo tee -a /etc/containerd/config.toml > /dev/null
+sudo systemctl restart containerd
+```
+
+Next we will create a RuntimeClass in Kubernetes to specify usage of wasmedge runtime for objects labeled as `runtime=wasm`
+
+```bash
+sudo cluster/kubectl.sh apply -f - <<< '{"apiVersion":"node.k8s.io/v1","kind":"RuntimeClass","metadata":{"name":"wasm"},"scheduling":{"nodeSelector":{"runtime":"wasm"}},"handler":"wasmedge"}'
+```
+
+Now we will label the kubernetes node as `runtime=wasm`. Note that the node where we changed the containerd configurations will be the one which we will label.
+
+An example of how we can label the node is given below:
+
+```bash
+sudo cluster/kubectl.sh get nodes
+# Sample output from the command above
+NAME        STATUS     ROLES    AGE    VERSION
+127.0.0.1   Ready   <none>   3h4m   v1.22.2
+# Run the following command to label the node 
+sudo cluster/kubectl.sh label nodes 127.0.0.1 runtime=wasm
+# A successful output from the above command looks like this
+node/127.0.0.1 labeled
+```
+### A WebAssembly-based HTTP service
+
+[A separate article](https://github.com/second-state/wasmedge-containers-examples/blob/main/http_server_wasi_app.md) explains how to compile, package, and publish a simple WebAssembly HTTP service application as a container image to Docker hub. Run the WebAssembly-based image from Docker Hub in the Kubernetes cluster as follows.
+
+```bash
+sudo cluster/kubectl.sh apply -f - <<< '{"apiVersion":"apps/v1","kind":"Deployment","metadata":{"name":"http-server-deployment"},"spec":{"replicas":1,"selector":{"matchLabels":{"app":"http-server"}},"template":{"metadata":{"labels":{"app":"http-server"}},"spec":{"hostNetwork":true,"runtimeClassName":"wasm","containers":[{"name":"http-server","image":"wasmedge/example-wasi-http:latest","ports":[{"containerPort":1234}]}]}}}}'
+```
+
+Since we are using `hostNetwork` in the `kubectl run` command, the HTTP server image is running on the local network with IP address `127.0.0.1`. Now, you can use the `curl` command to access the HTTP service.
+
+```bash
+$ curl -d "name=WasmEdge" -X POST http://127.0.0.1:1234
+echo: name=WasmEdge
+```
+
+That's it!
+
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