Python bug fix - Add jupyterlab even if python is not installed by Feature but exists (#244)

* python fix bug

* fix test

* address comments

* address comment

src/python/devcontainer-feature.json

 {
   "id": "python",
-  "version": "1.0.13",
+  "version": "1.0.14",
   "name": "Python",
   "documentationURL": "https://github.com/devcontainers/features/tree/main/src/python",
   "description": "Installs the provided version of Python, as well as PIPX, and other common Python utilities.  JupyterLab is conditionally installed with the python feature. Note: May require source code compilation.",

src/python/install.sh

@@ -322,7 +322,7 @@ sudo_if() {
 
 install_user_package() {
     PACKAGE="$1"
-    sudo_if "$INSTALL_PATH/bin/python3" -m pip install --user --upgrade --no-cache-dir "$PACKAGE"
+    sudo_if "${PYTHON_SRC}" -m pip install --user --upgrade --no-cache-dir "$PACKAGE"
 }
 
 add_user_jupyter_config() {
@@ -413,6 +413,10 @@ if [ "${PYTHON_VERSION}" != "none" ]; then
     chown -R "${USERNAME}:python" "${PYTHON_INSTALL_PATH}"
     chmod -R g+r+w "${PYTHON_INSTALL_PATH}"
     find "${PYTHON_INSTALL_PATH}" -type d -print0 | xargs -0 -n 1 chmod g+s
+
+    PYTHON_SRC="${INSTALL_PATH}/bin/python3"
+else
+    PYTHON_SRC=$(which python)
 fi
 
 # Install Python tools if needed
@@ -464,6 +468,11 @@ fi
 
 # Install JupyterLab if needed
 if [ "${INSTALL_JUPYTERLAB}" = "true" ]; then
+    if [ -z "${PYTHON_SRC}" ]; then
+        echo "(!) Could not install Jupyterlab. Python not found."
+        exit 1
+    fi
+
     install_user_package jupyterlab
     install_user_package jupyterlab-git
 

test/python/install_jupyterlab_from_python_image.sh

+#!/bin/bash
+
+set -e
+
+# Optional: Import test library
+source dev-container-features-test-lib
+
+# Always run these checks as the non-root user
+user="$(whoami)"
+check "user" grep vscode <<< "$user"
+
+# Check for an installation of JupyterLab
+check "version" jupyter lab --version
+
+# Report result
+reportResults

test/python/scenarios.json

@@ -13,6 +13,7 @@
         "remoteUser": "vscode",
         "features": {
             "python": {
+                "version": "latest",
                 "installJupyterlab": true,
                 "configureJupyterlabAllowOrigin": "*"
             }
@@ -36,6 +37,17 @@
             "python": "os-provided"
         }
     },
+    "install_jupyterlab_from_python_image": {
+        "image": "mcr.microsoft.com/devcontainers/python:3.10-bullseye",
+        "remoteUser": "vscode",
+        "features": {
+            "python": {
+                "version": "none",
+                "installTools": false,
+                "installJupyterlab": true
+            }
+        }
+    },
     "install_via_oryx": {
         "image": "mcr.microsoft.com/oryx/build:full-debian-bullseye",
         "features": {