Add a devcontainer config (#1432)

GitHub supports [dev containers][dc] to describe reproducible
development environments (e.g. for use from VS code). This change
introduces a devcontainer.json and Dockerfile to support container-based
development. This setup configures docker-in-docker so that docker and
k3d can be run inside the dev container.

This base configuration can be amended with per-user personalizations
via a [dotfiles][df] repo. For example: github.com/olix0r/dotfiles.

[dc]: https://docs.github.com/en/codespaces/setting-up-your-project-for-codespaces/configuring-codespaces-for-your-project
[df]: https://docs.github.com/en/codespaces/customizing-your-codespace/personalizing-codespaces-for-your-account

Signed-off-by: Oliver Gould <ver@buoyant.io>

.devcontainer/Dockerfile

@@ -0,0 +1,49 @@
+FROM docker.io/rust:1.56.1-bullseye
+
+ENV DEBIAN_FRONTEND=noninteractive
+RUN apt update && apt upgrade -y
+RUN apt install -y \
+    clang \
+    cmake \
+    golang \
+    lldb \
+    lsb-release \
+    sudo \
+    time
+
+ARG USER=code
+ARG USER_UID=1000
+ARG USER_GID=1000
+RUN groupadd --gid=$USER_GID $USER \
+    && useradd --uid=$USER_UID --gid=$USER_GID -m $USER \
+    && echo "$USER ALL=(root) NOPASSWD:ALL" >/etc/sudoers.d/$USER \
+    && chmod 0440 /etc/sudoers.d/$USER
+
+# Install a Docker client that uses the host's Docker daemon
+ARG USE_MOBY=false
+ENV DOCKER_BUILDKIT=1
+RUN curl --proto '=https' --tlsv1.3 -vsSfL https://raw.githubusercontent.com/microsoft/vscode-dev-containers/main/script-library/docker-debian.sh \
+    | bash -s -- true /var/run/docker-host.sock /var/run/docker.sock "${USER}" "${USE_MOBY}" latest
+
+USER $USER
+ENV HOME=/home/$USER
+RUN mkdir -p $HOME/bin
+ENV PATH=$HOME/bin:$PATH
+
+RUN curl --proto '=https' --tlsv1.3 -vsSfLo $HOME/kubectl "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl" \
+    && chmod 755 $HOME/kubectl
+RUN curl --proto '=https' --tlsv1.3 -vsSfL https://raw.githubusercontent.com/rancher/k3d/main/install.sh \
+    | USE_SUDO=false K3D_INSTALL_DIR=$HOME/bin bash
+
+RUN rustup component add clippy rustfmt
+RUN mkdir /tmp/cargo-deny && cd /tmp/cargo-deny && \
+    curl --proto '=https' --tlsv1.3 -vsSfL https://github.com/EmbarkStudios/cargo-deny/releases/download/0.11.0/cargo-deny-0.11.0-x86_64-unknown-linux-musl.tar.gz \
+        | tar zxf - \
+    && mv cargo-deny-0.11.0-x86_64-unknown-linux-musl/cargo-deny $HOME/bin \
+    && cd .. && rm -rf /tmp/cargo-deny
+
+RUN curl --proto '=https' --tlsv1.3 -vsSfL https://run.linkerd.io/install-edge | sh \
+    && ln -s $(readlink ~/.linkerd2/bin/linkerd) ~/bin/linkerd
+
+ENTRYPOINT ["/usr/local/share/docker-init.sh"]
+CMD ["sleep", "infinity"]

.devcontainer/devcontainer.json

@@ -0,0 +1,29 @@
+{
+	"name": "linkerd2-proxy",
+	"image": "ghcr.io/linkerd/dev-proxy:v3",
+	//"dockerFile": "./Dockerfile",
+	"extensions": [
+		"DavidAnson.vscode-markdownlint",
+		"matklad.rust-analyzer",
+		"NathanRidley.autotrim",
+		"samverschueren.final-newline",
+		"streetsidesoftware.code-spell-checker",
+		"tamasfe.even-better-toml",
+		"vadimcn.vscode-lldb",
+		"zxh404.vscode-proto3"
+	],
+	// Support docker + debugger
+	"runArgs": [
+		"--init",
+		// Use the host network so we can access k3d, etc.
+		"--net=host",
+		// For lldb
+		"--cap-add=SYS_PTRACE",
+		"--security-opt=seccomp=unconfined"
+	],
+	"overrideCommand": false,
+	"remoteUser": "code",
+	"mounts": [
+		"source=/var/run/docker.sock,target=/var/run/docker-host.sock,type=bind"
+	]
+}