Adds a dev container and Codespaces docs

Signed-off-by: Samruddhi Khandale <samruddhikhandale@github.com>

.devcontainer/Dockerfile

@@ -0,0 +1,28 @@
+# For details, see https://github.com/devcontainers/images/tree/main/src/base-ubuntu
+FROM mcr.microsoft.com/devcontainers/base:1-ubuntu-22.04
+
+RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
+    && apt-get -y install --no-install-recommends \
+        gperf \
+        dmsetup \
+        bc \
+        software-properties-common \
+        libseccomp-dev \
+        xfsprogs \
+        lsof \
+        iptables \
+        autoconf \
+        automake \
+        g++ \
+        libtool \
+        acl \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN add-apt-repository -y ppa:criu/ppa \
+    && apt-get update \
+    && apt-get install -y criu \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN setfacl -PRdm u::rwx,g::rx,o::rx /tmp
+
+COPY .devcontainer/welcome-message.txt /usr/local/etc/vscode-dev-containers/first-run-notice.txt

.devcontainer/devcontainer.json

@@ -0,0 +1,32 @@
+// For format details, see https://aka.ms/devcontainer.json.
+{
+	"name": "containerd",
+	"build": {
+		"context": "..",
+		"dockerfile": "Dockerfile"
+	},
+	"workspaceFolder": "/go/src/github.com/containerd/containerd",
+	"workspaceMount": "source=${localWorkspaceFolder},target=/go/src/github.com/containerd/containerd,type=bind,consistency=cached",
+
+	// Features to add to the dev container. More info: https://containers.dev/features.
+	"features": {
+		"ghcr.io/devcontainers/features/docker-in-docker:2": {},
+		"ghcr.io/devcontainers/features/go:1": {
+			"version": "1.20"
+		}
+	},
+
+	"onCreateCommand": "sudo PATH=$PATH bash .devcontainer/setup.sh",
+	"postAttachCommand": {
+		"Runs all non-integration tests that do not require `root` privileges": "make test",
+		"Runs non-integration tests which require `root`": "sudo PATH=$PATH  make root-test"
+	},
+
+	"remoteUser": "root",
+	"runArgs": [
+		"--ipc=host",
+		"--volume=/dev:/dev",
+		"--volume=/run/udev:/run/udev",
+		"--privileged"
+	]
+}

.devcontainer/setup.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+
+#   Copyright The containerd Authors.
+
+#   Licensed under the Apache License, Version 2.0 (the "License");
+#   you may not use this file except in compliance with the License.
+#   You may obtain a copy of the License at
+
+#       http://www.apache.org/licenses/LICENSE-2.0
+
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the License is distributed on an "AS IS" BASIS,
+#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#   See the License for the specific language governing permissions and
+#   limitations under the License.
+
+set -eux
+
+script/setup/install-seccomp
+script/setup/install-runc
+script/setup/install-cni $(grep containernetworking/plugins go.mod | awk '{print $2}')
+script/setup/install-critools
+script/setup/install-failpoint-binaries
+script/setup/install-gotestsum
+script/setup/install-teststat
+
+script/setup/install-protobuf \
+    && mkdir -p /go/src/usr/local/bin /go/src/usr/local/include \
+    && mv /usr/local/bin/protoc /go/src/usr/local/bin/protoc \
+    && mv /usr/local/include/google /go/src/usr/local/include/google
+
+make binaries GO_BUILD_FLAGS="-mod=vendor"
+sudo -E PATH=$PATH make install

.devcontainer/welcome-message.txt

@@ -0,0 +1,7 @@
+👋 Welcome to "containerd" in GitHub Codespaces!
+
+🛠️  Your environment is fully setup with all the required software.
+
+🔍 To explore VS Code to its fullest, search using the Command Palette (Cmd/Ctrl + Shift + P or F1).
+
+ℹ️  Look at https://github.com/containerd/project/blob/main/CONTRIBUTING.md for contribution guidelines.

BUILDING.md

@@ -4,12 +4,23 @@ This guide is useful if you intend to contribute on containerd. Thanks for your
 effort. Every contribution is very appreciated.
 
 This doc includes:
+* [Getting started with GitHub Codespaces](#getting-started-with-gitHub-codespaces)
 * [Build requirements](#build-requirements)
 * [Build the development environment](#build-the-development-environment)
 * [Build containerd](#build-containerd)
 * [Via docker container](#via-docker-container)
 * [Testing](#testing-containerd)
 
+## Getting started with GitHub Codespaces
+
+To get started, create a codespace for this repository by clicking this 👇
+
+[![Open in GitHub Codespaces](https://github.com/codespaces/badge.svg)](https://github.com/codespaces/new?hide_repo_select=true&ref=main&repo=46089560)
+
+A codespace will open in a web-based version of Visual Studio Code. The [dev container](.devcontainer/devcontainer.json) is fully configured with software needed for this project and the containerd built. If you use a codespace, then you can directly skip to the [testing](#testing-containerd) section of this document.
+
+**Note**: Dev containers is an open spec which is supported by [GitHub Codespaces](https://github.com/codespaces) and [other tools](https://containers.dev/supporting).
+
 ## Build requirements
 
 To build the `containerd` daemon, and the `ctr` simple test client, the following build system dependencies are required: