---
title: README
emoji: 👀
colorFrom: blue
colorTo: red
sdk: static
pinned: false
---
Spaces Dev Mode is currently in beta. It's available for
PRO users (personnal Spaces) or
Enterprise organizations (org Spaces).
Please share your feedback about Spaces Dev Mode in the
Community tab.
# Spaces Dev Mode (feature preview)
## About Spaces
Spaces offer a simple way to host ML demos and apps on your profile or your organization's profile.
In essence, a Space is a Docker container that runs your application.
Learn more about Spaces here: https://huggingface.co/docs/hub/spaces.
## Spaces Dev Mode
Whenever your commit some changes to your Space repo, the underlying Docker image gets rebuilt, and then a new virtual machine is provisioned to host the new container.
The Dev Mode allows you to update your Space much quicker by overriding the Docker image.
The Dev Mode Docker image starts your application as a sub-process, allowing you to restart it without stopping the Space container itself.
It also starts a VS Code server and a SSH server in the background for you to connect to the Space.
The ability to connect to the running Space unlocks several use cases:
- You can make changes to the app code without the Space rebuilding everytime
- You can debug a running application and monitor resources live
Overall it makes developing and experimenting with Spaces much faster by skipping the Docker image rebuild phase.
## Interface
Once the Dev Mode is enabled on your Space, you should see a modal like the following.
The application does not restart automatically when you change the code. For your changes to appear in the Space, you need to use the `Refresh` button that will restart the app.
If you're using the Streamlit or Gradio SDK, or if your application is Pyhton-based, note that requirements are not installed automatically.
You will need to manually run `pip install` from VS Code or SSH.
### Persisting changes
The changes you make when the Dev Mode is enabled are not persisted to the Space repo automatically.
By default, they will be discarded when the Dev Mode is disabled or when the Space goes to sleep.
If you wish to persist changes made while the Dev Mode is enabled, you need to use `git` from inside the Space container (using VS Code or SSH). For example:
```shell
# Add changes and commit them
git add .
git commit -m "Persist changes from Dev Mode"
# Push the commit to persist them in the repo
git push
```
The modal will display a warning if you have uncommitted or unpushed changes in the Space:
### How to enable the Dev Mode
Go to your Space's settings and click on "Enable Dev Mode".
You can also enable the Dev Mode from the quick actions dropdown.
## Limitations
The Dev Mode is currently not available for static Spaces. Docker Spaces also have some additional requirements.
### 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.
1. The following packages must be installed:
- `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.
The Dev Mode works well when the base image is debian-based (eg, ubuntu).
More exotic linux distros (eg, alpine) are not tested and the Dev Mode is not guaranteed to work on them.
### 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"]
```