Towards deprecating jupyterlite-xeus-python (#198)

* Towards deprecating jupyterlite-xeus-python

* Improve diff

* Linter

Author: martinRenou

Diff for: README.md

@@ -1,5 +1,9 @@
 # jupyterlite-xeus-python
 
+> [!WARNING]
+> jupyterlite-xeus-python is DEPRECATED
+> See [the migration guide](https://xeus-python-kernel.readthedocs.io/en/latest/migration.html)
+
 [![ci-badge]][ci] [![docs-badge]][docs]
 
 [ci-badge]: https://github.com/jupyterlite/xeus-python-kernel/workflows/Build/badge.svg

Diff for: docs/index.md

@@ -2,6 +2,10 @@
 
 The [xeus-python](https://github.com/jupyter-xeus/xeus-python) kernel compiled to WebAssembly and installable in JupyterLite!
 
+> [!WARNING]
+> jupyterlite-xeus-python is DEPRECATED
+> Please see {ref}`migration`
+
 Features:
 
 - all IPython features included (magics, matplotlib inline `etc`)
@@ -33,5 +37,6 @@ How does it compare to the [Pyodide kernel](https://github.com/jupyterlite/pyodi
 installation
 deploy
 configuration
+migration
 changelog
 ```

Diff for: docs/migration.md

@@ -0,0 +1,54 @@
+(migration)=
+
+# **jupyterlite-xeus-python** deprecation
+
+**jupyterlite-xeus-python** is being deprecated over [jupyterlite-xeus](https://github.com/jupyterlite/xeus) as of January 2024, you will find in this page migration steps to this new package.
+
+**jupyterlite-xeus** is a generalized approach of installing xeus-based kernels into a JupyterLite deployment. Using this new library, the main entry point is an `environment.yml` file, specifying your kernel environment including kernels and runtime dependencies.
+
+Example of an `environment.yml`:
+
+```yml
+name: my-jupyterlite-env
+channels:
+  - https://repo.mamba.pm/emscripten-forge
+  - conda-forge
+dependencies:
+  - xeus-python
+  - xeus-lua
+  - numpy
+  - matplotlib
+  - pip:
+      - ipywidgets
+```
+
+# Migrating to **jupyterlite-xeus**
+
+## Base setup
+
+Considering you have a simple setup where you install **jupyterlite-xeus-python** and have an **environment.yml** file with your dependencies:
+
+You will now need to install **jupyterlite-xeus** in your build environment instead of **jupyterlite-xeus-python**, and the diff for your **environment.yml** should look like the following (adding **xeus-python** explicitely in the runtime):
+
+```diff
+ name: my-jupyterlite-env
+ channels:
+   - https://repo.mamba.pm/emscripten-forge
+   - conda-forge
+ dependencies:
++  - xeus-python
+   - numpy
+   - matplotlib
+```
+
+See https://github.com/jupyterlite/xeus-python-demo for a deployment using **jupyterlite-xeus**.
+
+## CLI options
+
+Considering you are using more options from **jupyterlite-xeus-python** like **empack_config**:
+
+- The **xeus_python_version** option is removed, you need to specify the xeus-python version you need in your **environment.yml** file
+- The **empack_config** option is still supported: `jupyter lite build --XeusPythonEnv.empack_config=./file.yml` becomes `jupyter lite build --XeusAddon.empack_config=./file.yml`
+- The **pin_packages** option is removed.
+- The **packages** option is removed, you need to specify your dependencies in **environment.yml** only
+- The **environment_file** is still supported: `jupyter lite build --XeusPythonEnv.environment_file=./file.yml` becomes `jupyter lite build --XeusAddon.environment_file=./file.yml`. Defaults to **environment.yml**.