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containerd + crun

Quick start​

The GitHub repo contains scripts and GitHub Actions for running our example apps on containerd.

In the sections below, we will explain the steps in the quick start scripts.

Install containerd​

Use the following commands to install containerd on your system.

export VERSION="1.5.7"
echo -e "Version: $VERSION"
echo -e "Installing libseccomp2 ..."
sudo apt install -y libseccomp2
echo -e "Installing wget"
sudo apt install -y wget

wget https://github.com/containerd/containerd/releases/download/v${VERSION}/cri-containerd-cni-${VERSION}-linux-amd64.tar.gz
wget https://github.com/containerd/containerd/releases/download/v${VERSION}/cri-containerd-cni-${VERSION}-linux-amd64.tar.gz.sha256sum
sha256sum --check cri-containerd-cni-${VERSION}-linux-amd64.tar.gz.sha256sum

sudo tar --no-overwrite-dir -C / -xzf cri-containerd-cni-${VERSION}-linux-amd64.tar.gz
sudo systemctl daemon-reload

Configure containerd to use crun as the underlying OCI runtime. It changes the /etc/containerd/config.toml file.

sudo mkdir -p /etc/containerd/
sudo bash -c "containerd config default > /etc/containerd/config.toml"
wget https://raw.githubusercontent.com/second-state/wasmedge-containers-examples/main/containerd/containerd_config.diff
sudo patch -d/ -p0 < containerd_config.diff

Start the containerd service.

sudo systemctl start containerd

Next, make sure that you have built and installed the crun binary with WasmEdge support before running the following examples.

Run a simple WebAssembly app​

Now, we can run a simple WebAssembly program using containerd. A separate article explains how to compile, package, and publish the WebAssembly program as a container image to Docker hub. This section will start pulling this WebAssembly-based container image from the Docker hub using containerd tools.

sudo ctr i pull docker.io/wasmedge/example-wasi:latest

Now, you can run the example in just one line with ctr (the containerd cli).

sudo ctr run --rm --runc-binary crun --runtime io.containerd.runc.v2 --label module.wasm.image/variant=compat-smart docker.io/wasmedge/example-wasi:latest wasm-example /wasi_example_main.wasm 50000000

Starting the container would execute the WebAssembly program. You can see the output in the console.

Creating POD ...
Random number: -1678124602
Random bytes: [12, 222, 246, 184, 139, 182, 97, 3, 74, 155, 107, 243, 20, 164, 175, 250, 60, 9, 98, 25, 244, 92, 224, 233, 221, 196, 112, 97, 151, 155, 19, 204, 54, 136, 171, 93, 204, 129, 177, 163, 187, 52, 33, 32, 63, 104, 128, 20, 204, 60, 40, 183, 236, 220, 130, 41, 74, 181, 103, 178, 43, 231, 92, 211, 219, 47, 223, 137, 70, 70, 132, 96, 208, 126, 142, 0, 133, 166, 112, 63, 126, 164, 122, 49, 94, 80, 26, 110, 124, 114, 108, 90, 62, 250, 195, 19, 189, 203, 175, 189, 236, 112, 203, 230, 104, 130, 150, 39, 113, 240, 17, 252, 115, 42, 12, 185, 62, 145, 161, 3, 37, 161, 195, 138, 232, 39, 235, 222]
Printed from wasi: This is from a main function
This is from a main function
The env vars are as follows.
The args are as follows.
/wasi_example_main.wasm
50000000
File content is This is in a file

Next, you can run it in Kubernetes!

Run a HTTP server app​

Finally, we can run a simple WebAssembly-based HTTP micro-service in containerd. A separate article explains how to compile, package, and publish the WebAssembly program as a container image to Docker hub. This section will start pulling this WebAssembly-based container image from the Docker hub using containerd tools.

sudo ctr i pull docker.io/wasmedge/example-wasi-http:latest

Now, you can run the example in just one line with ctr (the containerd cli). Notice that we are running the container with --net-host so that the HTTP server inside the WasmEdge container is accessible from the outside shell.

sudo ctr run --rm --net-host --runc-binary crun --runtime io.containerd.runc.v2 --label module.wasm.image/variant=compat-smart docker.io/wasmedge/example-wasi-http:latest http-server-example /http_server.wasm

Starting the container would execute the WebAssembly program. You can see the output in the console.

new connection at 1234

# Test the HTTP service at that IP address
curl -d "name=WasmEdge" -X POST http://127.0.0.1:1234
echo: name=WasmEdge

Next, you can run it in Kubernetes!