Merge pull request #61 from rumpl/document-init

Add documentation about the init command

Author: gtardif

docs/dev/cli/usage.md

@@ -4,6 +4,7 @@ The Extensions CLI is an extension development tool that can be used to manage D
 
 - `docker extension enable` - enable Docker extensions
 - `docker extension disable` - disable Docker extensions
+- `docker extension init` -  create a new Docker extension
 - `docker extension install ` - install a Docker Extension with the specified image
 - `docker extension ls` - list installed Docker extensions
 - `docker extension rm` - remove a Docker extension

docs/tutorials/images/initialized-extension.png

@@ -0,0 +1,139 @@
+In this tutorial you will learn how to create a new Docker Desktop extension
+
+## Prerequisites
+
+- [Docker Desktop build with Extensions capabilities](https://github.com/docker/desktop-extension-samples/releases/)
+- [Docker Extensions CLI](https://github.com/docker/desktop-extension-samples/releases/)
+- [node](https://nodejs.org)
+
+## Creating a new extension
+
+To create a new extension run
+
+```bash
+docker extension init my-extension
+```
+
+and answer the questions.
+
+This will create a directory `my-extension` with a bare-bones extension code.
+
+This extension contains:
+
+- A backend that listens on a socket, it has one endpoint `/hello` that returns
+  a JSON payload
+- A React frontend that can call the backend and output the backend response
+
+## Build the extension
+
+```bash
+cd my-extension
+make extension
+```
+
+## Install the extension
+
+Now that the extension is packaged as a Docker image, let's proceed with the
+installation. To do so, we'll use the Docker Extensions CLI.
+
+!!! info "Enable Docker Desktop Extensions"
+
+    Ensure the Extensions capabilities are enabled in the Docker Desktop build
+    by running `docker extension enable`
+
+To install the extension in Docker Desktop, run:
+
+```bash
+docker extension install my-extension
+```
+
+If the installation was successful, you should see the following output:
+
+```bash
+Installing new extension "my-extension"
+Installing service in Desktop VM...
+Setting additional compose attributes
+VM service started
+Installing Desktop extension UI for tab "My-Extension"...
+Extension UI tab "My-Extension" added.
+Extension "my-extension" installed successfully
+```
+
+## Preview the extension
+
+You can verify that the extension has been installed successfully using the
+following CLI command:
+
+```bash
+docker extension ls
+```
+
+It outputs all the extensions installed:
+
+```bash
+ID                  PROVIDER            VERSION             UI                    VM                  HOST
+my-extension        Docker Inc.                             1 tab(My-Extension)   Running(1)          -
+```
+
+On the left-menu, you should see a new tab with the name `My-Extension`. Click
+on it to load the main window that will render a button. When you click on it
+you should see the response from the backend
+
+![UI Extension](images/initialized-extension.png)
+
+### Opening Dev Tools
+
+To open the Chrome Developer Tools, see [this](../../dev/overview).
+
+### Iterate faster while developing
+
+To iterate faster and try out new changes when developing the extension, use the `docker extension update` command to uninstall the previous version and install the new one with your latest changes.
+
+### Developing the frontend
+
+If you are working on the frontend code of your extension and don't want to
+rebuild the extension image each time you can setup Docker Desktop in a way
+that will use your development server instead of the bundled frontend code from
+the extension image. To do that, in one terminal start your UI development
+server:
+
+```bash
+cd ui
+npm start
+```
+
+This will start a development server that listens on port 3000. You can now tell
+Docker Desktop to use this as the frontend source, in another terminal run:
+
+```bash
+docker extension dev ui-source my-extension http://localhost:3000
+```
+
+Close and reoped the Docker Desktop dashboard and go to your extension, all the
+changes to the frontend code will now be immediately visible.
+
+Once you are done you can remove the ui-source override by running
+
+```bash
+docker extension dev reset my-extension
+```
+
+
+## Clean up
+
+To remove the extension run:
+
+```bash
+docker extension rm my-extension
+```
+
+The following output should be displayed:
+
+```bash
+Removing extension my-extension...
+Removing extension VM service...
+Extension removed from Desktop VM
+VM service socket forwarding stopped
+Extension UI tab My-Extension removed
+Extension "my-extension" removed
+```

docs/tutorials/initialize.md

@@ -39,6 +39,7 @@ markdown_extensions:
 nav:
   - Introduction: index.md
   - Tutorials:
+      - Create your first extension: tutorials/initialize.md
       - Create a minimal frontend extension: tutorials/minimal-frontend-extension.md
       - Create a minimal backend extension: tutorials/minimal-backend-extension.md
       - Create a ReactJS-based extension: tutorials/react-extension.md