Add a Devcontainer (#6290)

.devcontainer/devcontainer.json

@@ -0,0 +1,22 @@
+{
+  "name": "moto",
+  "image": "mcr.microsoft.com/devcontainers/python:0-3.11",
+  "remoteUser": "root",
+  "features": {
+    "ghcr.io/devcontainers/features/docker-in-docker:2": {}
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": ["ms-vscode.makefile-tools", "ms-python.python", "ms-python.black-formatter"],
+      "settings": {
+        "python.defaultInterpreterPath": "${workspaceFolder}/.venv",
+        "python.formatting.provider": "none",
+        "[python]": {
+          "editor.defaultFormatter": "ms-python.black-formatter"
+        }
+      }
+    }
+  },
+  "postCreateCommand": "python -m venv .venv",
+  "postStartCommand": ". .venv/bin/activate && make init"
+}

docs/docs/contributing/installation.rst

@@ -52,3 +52,31 @@ If black fails, you can run the following command to automatically format the of
   make format
 
 If any of these steps fail, please see our :ref:`contributing faq` or open an issue on Github.
+
+Development within a Devcontainer
+==================================
+
+Moto is equipped with a `devcontainer.json` for use in VSCode Devcontainers and/or GitHub Codespaces.
+
+Launching the Devcontainer or Codespace:
+
+ - Configures Docker-in-Docker.
+ - Sets up a Virtual Environment in `${workspaceFolder}/.venv`.
+ - Runs `make init`.
+
+Be patient while the Devcontainer or Codespace launches as dependencies automatically installed. 
+
+Once both `postCreateCommand` and `postStartCommand` have run, open a Terminal session in VSCode and run:
+
+.. code-block:: bash
+
+  source .venv/bin/activate
+
+Then standard development on Moto can proceed, for example:
+
+.. code-block:: bash
+
+  flake8 moto/s3
+  black --check moto/s3 tests/test_s3
+  pylint tests/test_s3
+  pytest -sv tests/test_s3