document how to run this codespace in a docker container

README.md

@@ -29,6 +29,7 @@ Besides Rust and Cargo, the image comes with the following Rust related tooling:
 
 ### VS Code Extensions
 
+- [Rust](https://marketplace.visualstudio.com/items?itemName=rust-lang.rust): Rust default extension.
 - [Rust Analyzer](https://marketplace.visualstudio.com/items?itemName=matklad.rust-analyzer): an alternative rust language server to the RLS.
 - [CodeLLDB](https://marketplace.visualstudio.com/items?itemName=vadimcn.vscode-lldb): native debugger based on LLDB.
 - [Crates](https://marketplace.visualstudio.com/items?itemName=serayuzgur.crates): helps Rust developers managing dependencies with Cargo.toml.
@@ -40,15 +41,15 @@ Besides Rust and Cargo, the image comes with the following Rust related tooling:
 
 ## Usage
 
-### In VS Codespaces
+### Online VS Codespaces
 
 #### Inital Creation
 
 For usage in VS Codespaces, you're going to want to head over to [online.visualstudio.com](https://online.visualstudio.com) and sign up for VS Codespaces (that process is outside the scope of these instructions). Once you've got an account and are signed in to [online.visualstudio.com](https://online.visualstudio.com), you're going to take the following steps:
 
 - Ensure you're on the `/environments` page at [online.visualstudio.com/environments](https://online.visualstudio.com/environments)
 - In the top right corner, there'll be a "Create environment" button. Click this button, which will open up a panel from the right side of the screen. Fill in the details of this panel:
-  - **Codespace Name:** This will be the visible name of your environment within Codespaces. The value here doesn't particularly matter. 
+  - **Codespace Name:** This will be the visible name of your environment within Codespaces. The value here doesn't particularly matter.
   - **Git Repository:** This is going to be either the URL you'd `git clone` the repo from or the GitHub `<org OR user>/<repo>` shorthand. For this repo, the easier value would be `codespaces-examples/base`.
   - **Instance Type:** For this, you're going to choose your plan - in my case, I'm just going to go with the `Standard (Linux)` plan. For most use cases of this starter, `Basic (Linux)` should suffice. You can also change your plan at any time, as your workload demands.
   - **Suspend idle environment after:** This is the period of time you want your environment to automatically suspend after you've stopped actively using it. I generally chose 5 minutes and have not had any problems to date.
@@ -74,6 +75,34 @@ Additionally, if you've installedthe [Visual Studio Codespaces](https://marketpl
 
 Now that you're set up and connected, you should be able to work within your Codespaces environment.
 
+### VS Codespaces inside a Docker container
+
+Using [Visual Studio Code](https://code.visualstudio.com/) and a [specific extension](https://aka.ms/vscode-remote/download/extension), we can load this codespace in a brand new local [Docker](https://docker.com/) container and use it as a full-featured development environment. Note that this approach requires a few more steps than using the online setup mentioned above. The advantages being that this works offline and there are no costs associated with this approach. It is a great way to play with a setup without having to install everything globally on one's machine!
+
+
+#### Requirements
+
+There are 3 main requirements: **VSCode**, **the Remote - Containers VSCode extension** and **Docker**.
+
+Follow the instruction [guide here](https://code.visualstudio.com/docs/remote/containers#_installation) and come back here once those 3 components are installed locally.
+
+### Setup
+
+To load the codespace in a container, we need to point to it. We have many options here, the main ones being to connect to a repository and the other one to open a local folder with the codespace repo checked out. We are going to take the easiest approach and setup the code space directly from this repository.
+
+1. In VSCode, click on the green icon in the lower left corner.
+
+![](https://code.visualstudio.com/assets/docs/remote/common/remote-dev-status-bar.png)
+
+2. Choose  `Remote-Containers: Open Repository in container`
+3. Type `codespaces-examples/rust` in the prompt.
+4. Chose to create a unique volume.
+5. Wait until the container is setup and you are connected to it, at this point, it should ask you to install some missing Rust components, go ahead and say yes.
+![](https://user-images.githubusercontent.com/113/84210352-468ca100-aa6d-11ea-88c4-fdffa1b9e92a.png)
+
+That's it, you are all setup, you can modify and run the code in your local VSCode instance but the code and extensions will run in your container.
+
+
 ## Contributing
 
 Contributions are welcome. Please refrain from opinionated additions like linters. However, adding package managers and other DX improvements that are additive like `yarn` are welcome. Contributors must follow the [Code of Conduct](./CODE_OF_CONDUCT.md).