Update instructions for Docker-based Spaces

README.md

@@ -46,10 +46,41 @@ The dev mode is currently not available for static Spaces.
 
 ### Docker Spaces
 
-Dev mode is supported for Docker Spaces. However, your Space needs to comply with the following rules for the Dev mode to work properly:
+Dev mode is supported for Docker Spaces. However, your Space needs to comply with the following rules for the Dev mode to work properly.
 
-- `apt-get` must be installed in the container (base images such as `debian` or `ubuntu` have that package by default).
-- The Dockerfile must contain a `CMD` instruction for startup.
+1. The following packages must be installed:
 
-Checkout [Docker's documentation](https://docs.docker.com/reference/dockerfile/#cmd) about the `CMD` instruction for more details.
+- `bash` (required to establish SSH connections)
+- `curl`, `wget` and `procps` (required by the VS Code server process)
+- `git` and `git-lfs` to be able to commit and push changes from your dev mode environment
 
+2. Your application code must be located in the `/app` folder for the dev mode daemon to be able to detect changes.
+
+3. The `/app` folder must be owned by the user with uid `1000` to allow you to make changes to the code.
+
+4. The Dockerfile must contain a `CMD` instruction for startup. Checkout [Docker's documentation](https://docs.docker.com/reference/dockerfile/#cmd) about the `CMD` instruction for more details.
+
+### Example of a compatible Dockerfile
+
+This is an example of a Dockerfile compatible with Spaces dev mode.
+
+It installs the required packages with `apt-get`, along with a couple more for developer convenience (namely: `top`, `vim` and `nano`).
+It then starts a NodeJS application from `/app`.
+
+```Dockerfile
+FROM node:19-slim
+
+RUN RUN apt-get update && \
+    apt-get install -y \
+      bash \
+      git git-lfs \
+      wget curl procps \
+      htop vim nano && \
+    rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+COPY --link --chown=1000 ./ /app
+RUN  npm ci 
+
+CMD ["node", "index.mjs"]
+```