docker-in-docker (dind) devcontainer image to be used for labs (#2058)

* devcontainer init

* fix name

* cleanup devcontainer setup

* set user to "user" staticly

.github/containers/dind/Dockerfile

@@ -0,0 +1,5 @@
+FROM public.ecr.aws/docker/library/debian:12-slim
+
+# Switch to user
+USER user
+ENV PATH=$PATH:/home/${USERNAME}/.local/bin

.github/containers/dind/devcontainer.json

@@ -0,0 +1,32 @@
+// For format details, see https://aka.ms/devcontainer.json.
+{
+    "build": {
+        "dockerfile": "./Dockerfile",
+        "context": "."
+        // "args": {
+        //     "USERNAME": "${localEnv:USERNAME}"
+        // }
+    },
+    "features": {
+        "ghcr.io/devcontainers/features/docker-in-docker:2": {
+            "version": "latest",
+            "dockerDashComposeVersion": "none"
+        },
+        // Add sshd to support gh cli codespace cp.
+        "ghcr.io/devcontainers/features/sshd:1": {
+            "version": "latest"
+        }
+    },
+    "customizations": {
+        "vscode": {
+            "extensions": [
+                // Python.
+                "ms-python.python",
+                "ms-python.vscode-pylance",
+                // Errors and highlighters.
+                "mechatroner.rainbow-csv",
+                "oderwat.indent-rainbow"
+            ]
+        }
+    }
+}

.github/workflows/build-devcontainer.yml

@@ -0,0 +1,47 @@
+name: dind-devcontainer
+on:
+  workflow_dispatch:
+
+env:
+  REGISTRY: ghcr.io
+
+jobs:
+  dind-devcontainer:
+    name: lint
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log into registry ${{ env.REGISTRY }}
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract Docker metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ github.repository }}
+          tags: |
+            type=ref,event=branch
+            type=ref,event=pr
+            # git short commit
+            type=sha
+
+      - name: Pre-build dev container image 🔨
+        uses: devcontainers/[email protected]
+        # env:
+        #   USERNAME: ${{ inputs.username }}
+        #   UID: ${{ inputs.user_id }}
+        #   GID: ${{ inputs.group_id }}
+        with:
+          subFolder: .github/containers/dind
+          imageName: ghcr.io/${{ github.repository }}/clab-dind
+          imageTag: ${{ steps.meta.outputs.tags }}
+          push: always