dev: Use the common linkerd devcontainer image (kubernetes#1465)

This repo's devcontainer runs everything as root, which can lead to
weird permissions, especially in the `.git/` directory.

This change replaces the repo-specific devcontainer with the general
`linkerd/dev` container. Custom tools like `hugo`, `htmltest`, and
`gcloud` are installed via an on-create script.

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

.devcontainer/devcontainer.json

@@ -1,12 +1,26 @@
 {
-    "name": "website",
-    //"image": "buoyantio/website-builder:v1.3.3",
-    "build": {
-        "dockerfile": "../Dockerfile"
-    },
-    // "context": "..",
+    "name": "linkerd-website",
+    "image": "ghcr.io/linkerd/dev:v30",
+    "onCreateCommand": ".devcontainer/on-create.sh",
+    "extensions": [
+        "DavidAnson.vscode-markdownlint",
+        "dbaeumer.vscode-eslint",
+        "budparr.language-hugo-vscode",
+        "NathanRidley.autotrim",
+        "redhat.vscode-yaml",
+        "samverschueren.final-newline",
+        "tamasfe.even-better-toml"
+    ],
+    "runArgs": [
+        "--init",
+        // Limit container memory usage.
+        "--memory=4g",
+        "--memory-swap=4g",
+        // Use the host network so we can access k3d, etc.
+        "--net=host"
+    ],
     "overrideCommand": false,
-    "remoteUser": "root",
+    "remoteUser": "code",
     "mounts": [
         "source=/var/run/docker.sock,target=/var/run/docker-host.sock,type=bind"
     ]

.devcontainer/on-create.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+cd $(mktemp -d)
+
+# hugo
+scurl -O https://github.com/gohugoio/hugo/releases/download/v0.61.0/hugo_extended_0.61.0_Linux-64bit.deb
+sudo dpkg -i hugo*.deb
+rm hugo*.deb
+
+# htmltest
+scurl https://htmltest.wjdp.uk | bash
+sudo mv bin/htmltest /usr/local/bin
+
+# gcloud
+echo "deb [signed-by=/usr/share/keyrings/cloud.google.gpg] https://packages.cloud.google.com/apt cloud-sdk main" \
+    | sudo tee -a /etc/apt/sources.list.d/google-cloud-sdk.list
+scurl https://packages.cloud.google.com/apt/doc/apt-key.gpg \
+    | sudo apt-key --keyring /usr/share/keyrings/cloud.google.gpg add -
+sudo apt-get update
+sudo apt-get install google-cloud-cli