extensions: WIP accessing and modifying a running Extension container

development/extensions/index.md

@@ -291,7 +291,7 @@ Each Extension service with a `register_service` endpoint will have an entry in
 
 Different types of Extensions have different functionality, and there are often a variety of tools available to provide that. When starting to develop extensions, we would generally recommend:
 - Python to run stuff
-   - Frequently using a web framework like Starlite/Flask/FastAPI to provide the backend of an interface
+   - Frequently using a web framework like Litestar/Flask/FastAPI to provide the backend of an interface
 - Static HTML files to contain and display parts of an interface
 - Our [Extensions Examples Repository](https://github.com/BlueOS-Community/BlueOS-examples) has some useful examples
 
@@ -397,7 +397,7 @@ QuickStart repositories serve as a way to get an example Extension up and runnin
     - The name should be something like `blueos-extension-image-name` (e.g. `blueos-quickstart`)
 3. Set up [GitHub Secrets](https://docs.github.com/en/actions/security-guides/using-secrets-in-github-actions#creating-secrets-for-a-repository):
     - `DOCKER_USERNAME`: your Docker Hub username
-    - `DOCKER_PASSWORD`: a Read & Write [access token](https://docs.docker.com/security/for-developers/access-tokens/), to provide upload permissions from your GitHub repository to your Docker Hub account
+    - `DOCKER_PASSWORD`: a Docker Hub [access token](https://docs.docker.com/security/for-developers/access-tokens/) (Read & Write), to allow your GitHub repository actions to upload Docker images to your Docker Hub account
 4. Set up [GitHub Variables](https://docs.github.com/en/actions/learn-github-actions/variables#creating-configuration-variables-for-a-repository):
     - `IMAGE_NAME`: the name you chose for your Docker repository
     - `MY_EMAIL`: the developer's email address
@@ -436,7 +436,7 @@ For reference:
 
 Testing each Extension release before making it available to install from the online store is strongly recommended. 
 
-1. Go to the [Extensions Manager](../../advanced-usage#extensions-manager) in BlueOS
+1. Go to the [Extensions Manager](../../advanced-usage/#extensions-manager) in BlueOS
 1. Click on the "Installed" tab
 1. Click the "+" icon in the bottom right corner
 1. Enter the relevant information for your Docker Image, so it can be fetched from Docker Hub
@@ -454,6 +454,33 @@ Testing each Extension release before making it available to install from the on
     - `Custom settings`: the contents of your Dockerfile's `permissions` LABEL, but with relevant variable substitutions (e.g. `$IMAGE_NAME` → `blueos-quickstart`) and without the backslash line continuation characters
         - Used for configuration of the Docker container when it's run
 
+##### Accessing an Installed Extension's Docker Container
+
+It is possible to enter running Docker containers via the [Terminal](../../advanced-usage/#terminal), by 
+
+1. Running `red-pill` to exit the BlueOS-core container
+1. Running `docker container ls` to list the currently running Docker containers
+1. Running `docker attach -it container-name` to enter the container and see the outputs of the running process
+1. Pressing `CTRL+C` to stop the process (e.g. if you want to modify something)
+1. Pressing your keyboard's up arrow to find the command the container was last running (or running some alternative command instead)
+1. Pressing ...? (TODO) to exit the docker container
+
+If you made changes that you want to make persistent across future restarts it is necessary to `docker commit` a new Docker image from the container,
+and potentially overwrite the old one with it if you want it to operate in place of the original Extension.
+
+TODO: describe how to register an existing image as an Extension, if that's even possible.
+
+{% note() %}
+While this can be useful for testing minor changes during development (e.g. fixing a small bug, or adjusting some logging outputs), it is
+not recommended to upload commit-modified images as new Extension versions, because there's then no record in the source code repository of the change(s).
+{% end %}
+
+{% note() %}
+If you want to make changes to files that are mounted to the computer's filesystem (via `binds` in the `permissions` metadata LABEL) then that can instead
+be done via the [File Browser](../../advanced-usage/#file-browser), restarting the Extension afterwards if necessary. In that case the changes will be
+persistent once the modified file has been saved.
+{% end %}
+
 #### Submission to the Bazaar
 
 1. Check [metadata docs](#metadata-dockerfile), and match the requirements with your Dockerfile
@@ -487,6 +514,9 @@ The expected iteration process is:
 1. Confirm the new version is available through the BlueOS Extensions Manager
 1. Install and test it
 
+##### Modifying an Existing Docker Image
+
+
 
 - [Sneak peek diagram](https://github.com/bluerobotics/ardusub-zola/blob/BlueOS-1.1/development/extensions/development-process.mermaid)