[](https://vscode.dev/redirect?url=vscode://ms-vscode-remote.remote-containers/cloneInVolume?url=https://github.com/microsoft/vscode-remote-try-python)
A **development container** is a running [Docker](https://www.docker.com) container with a well-defined tool/runtime stack and its prerequisites. You can try out development containers with **[GitHub Codespaces](https://github.com/features/codespaces)** or **[Visual Studio Code Remote - Containers](https://aka.ms/vscode-remote/containers)**.
This is a sample project that lets you try out either option in a few easy steps. We have a variety of other [vscode-remote-try-*](https://github.com/search?q=org%3Amicrosoft+vscode-remote-try-&type=Repositories) sample projects, too.
For more information on creating your codespace, visit the [GitHub documentation](https://docs.github.com/en/free-pro-team@latest/github/developing-online-with-codespaces/creating-a-codespace#creating-a-codespace).
If you already have VS Code and Docker installed, you can click the badge above or [here](https://vscode.dev/redirect?url=vscode://ms-vscode-remote.remote-containers/cloneInVolume?url=https://github.com/microsoft/vscode-remote-try-python) to get started. Clicking these links will cause VS Code to automatically install the Remote - Containers extension if needed, clone the source code into a container volume, and spin up a dev container for use.
1. If this is your first time using a development container, please ensure your system meets the prerequisites (i.e. have Docker installed) in the [getting started steps](https://aka.ms/vscode-remote/containers/getting-started).
- Choose the "Python" sample, wait for the container to start, and try things out!
> **Note:** Under the hood, this will use the **Remote-Containers: Clone Repository in Container Volume...** command to clone the source code in a Docker volume instead of the local filesystem. [Volumes](https://docs.docker.com/storage/volumes/) are the preferred mechanism for persisting container data.
> **Note:** This container runs as a non-root user with sudo access by default. Comment out `"remoteUser": "vscode"` in `.devcontainer/devcontainer.json` if you'd prefer to run as root.
- Notice that the Python extension is already installed in the container since the `.devcontainer/devcontainer.json` lists `"ms-python.python"` as an extension to install automatically when the container is created.
> **Tip:** If you use this container outside of VS Code via `docker run` with `-p 9000`, you may need to append `--host 0.0.0.0` to the command above. The `-p` option "publishes" the port rather than forwarding it. It therefore will not work if the application only listens to localhost. The `forwardPorts` property in `devcontainer.json` does not have this limitation, but you can use `appPort` property instead if you want to mirror the `docker run` behavior.
- Continue (<kbd>F5</kbd>). You can connect to the server in the container by either:
- Clicking on `Open in Browser` in the notification telling you: `Your service running on port 9000 is available`.
- Clicking the globe icon in the 'Ports' view. The 'Ports' view gives you an organized table of your forwarded ports, and you can access it with the command **Ports: Focus on Ports View**.
- Notice port 9000 in the 'Ports' view is labeled "Hello Remote World." In `devcontainer.json`, you can set `"portsAttributes"`, such as a label for your forwarded ports and the action to be taken when the port is autoforwarded.
> **Note:** In Remote - Containers, you can access your app at `http://localhost:9000` in a local browser. But in a browser-based Codespace, you must click the link from the notification or the `Ports` view so that the service handles port forwarding in the browser and generates the correct URL.
You may want to make changes to your container, such as installing a different version of a software or forwarding a new port. You'll rebuild your container for your changes to take effect.
**Open browser automatically:** As an example change, let's update the `portsAttributes` in the `.devcontainer/devcontainer.json` file to open a browser when our port is automatically forwarded.
- Press <kbd>F1</kbd> and select the **Remote-Containers: Rebuild Container** or **Codespaces: Rebuild Container** command so the modifications are picked up.
