Add documentation about plugin enabling on pex

docs/backend_architecture/plugins.rst

@@ -44,6 +44,19 @@ Similarly, to disable the plugin the following command can be used:
 
     kolibri plugin disable kolibri.plugins.example_plugin
 
+.. note::
+    **Using externally-built plugins with PEX**
+
+    When using externally-built plugins (plugins installed separately from Kolibri's core installation) with a PEX distribution of Kolibri, you must set the environment variable ``PEX_INHERIT_PATH=1`` to enable the PEX file to access plugins installed in the system Python path.
+
+    For example:
+
+    .. code-block:: bash
+
+        PEX_INHERIT_PATH=1 python kolibri.pex start
+
+    This allows Kolibri to discover and use plugins that were installed via ``pip install`` outside of the PEX environment.
+
 To exactly set the currently enabled plugins (disabling all other plugins, and enabling the ones specified) you can do this:
 
 .. code-block:: bash

kolibri/utils/cli.py

@@ -1,4 +1,5 @@
 import logging
+import os
 import signal
 import sys
 import traceback
@@ -22,6 +23,7 @@
 from kolibri.utils import server
 from kolibri.utils.compat import module_exists
 from kolibri.utils.conf import OPTIONS
+from kolibri.utils.constants import installation_types
 from kolibri.utils.debian_check import check_debian_user
 from kolibri.utils.main import initialize
 from kolibri.utils.main import set_django_settings_and_python_path
@@ -390,6 +392,30 @@ def plugin():
     pass
 
 
+def generate_pex_error():
+    """
+    Format plugin error message with additional context for PEX installations.
+    """
+    if "PEX_INHERIT_PATH" in os.environ:
+        return ""
+
+    # Add PEX-specific help if running from PEX
+    current_installation = server.installation_type()
+    if (
+        current_installation
+        and installation_types.PEX.lower() in current_installation.lower()
+    ):
+        return (
+            "\n\nYou are running Kolibri from a PEX file. "
+            "To use externally-installed plugins with PEX, you must set the "
+            "PEX_INHERIT_PATH environment variable:\n\n"
+            "    PEX_INHERIT_PATH=1 python kolibri.pex start\n\n"
+            "This allows the PEX file to access plugins installed in the system Python path."
+        )
+
+    return ""
+
+
 @plugin.command(cls=KolibriCommand, help="Enable Kolibri plugins")
 @click.argument("plugin_names", nargs=-1)
 @click.option("-d", "--default-plugins", default=False, is_flag=True)
@@ -399,7 +425,9 @@ def enable(plugin_names, default_plugins):
     else:
         error = enable_plugins(plugin_names)
     if error:
-        exception = click.ClickException("One or more plugins could not be enabled")
+        exception = click.ClickException(
+            "One or more plugins could not be enabled" + generate_pex_error()
+        )
         exception.exit_code = 2
         raise exception
 
@@ -428,7 +456,7 @@ def apply(plugin_names):
     error = enable_plugins(plugin_names) or error
     if error:
         exception = click.ClickException(
-            "An error occurred applying the plugin configuration"
+            "An error occurred applying the plugin configuration" + generate_pex_error()
         )
         exception.exit_code = 2
         raise exception