Introduces environment variable MWI_CUSTOM_MATLAB_ROOT to instruct matlab-proxy to use specified MATLAB instead of using the MATLAB found on the system PATH.

fixes #3
fixes mathworks/jupyter-matlab-proxy#37

Author: diningPhilosopher64

Advanced-Usage.md

@@ -1,5 +1,5 @@
 # Advanced Usage
-Copyright (c) 2020-2022 The MathWorks, Inc. All rights reserved.
+Copyright (c) 2020-2023 The MathWorks, Inc. All rights reserved.
 
 This page lists some of the advanced manuevers that may be of specific interest to help configure the package for use in your environment.
 
@@ -29,6 +29,47 @@ The following table describes all the environment variables that you can set to
 | **MWI_ENABLE_TOKEN_AUTH** | string | `"True"` | When set to `True`, matlab-proxy will require users to provide the security token to access the proxy. <br />The default value is `False` . See [Token-Based Authentication](./SECURITY.md#token-based-authentication) for more information.|
 | **MWI_AUTH_TOKEN** | string (optional) | `"AnyURLSafeToken"` | Optionally, provide a custom `token` for use with `MWI_ENABLE_TOKEN_AUTH`. A token can safely contain any combination of alpha numeric text along with the following permitted characters: `- .  _  ~`.<br />When absent matlab-proxy will generate a random URL safe token. |
 | **MWI_USE_EXISTING_LICENSE** | string (optional) | `"True"` | When set to True, matlab-proxy will not ask you for additional licensing information and will try to launch an already activated MATLAB on your system PATH.
+| **MWI_CUSTOM_MATLAB_ROOT** | string (optional) | `"/path/to/matlab/root/"` | Optionally, provide a custom path to MATLAB root. For more information see [Adding MATLAB to System Path](#adding-matlab-to-system-path) |
+
+## Adding MATLAB to System Path
+
+When `matlab-proxy` starts, it expects the `matlab` executable to be present on  system PATH in the environment from which it was spawned.
+
+`matlab-proxy` will error out if it is unable to find `matlab` on the PATH.
+
+One can add it to the system PATH using the following commands:
+```bash
+# On Linux & MacOS
+sudo ln -fs ${MATLAB_ROOT}/bin/matlab /usr/bin/matlab
+
+# On Windows environments
+setx PATH "${MATLAB_ROOT}\bin;%PATH%"
+```
+Where `MATLAB_ROOT` points to the folder in which MATLAB was installed.
+Example values of `MATLAB_ROOT` on various platforms are:
+```
+On linux: /usr/local/MATLAB/R2023a
+On MacOS: /Applications/MATLAB_R2023a.app
+On Windows: C:\Program Files\MATLAB\R2023a
+```
+
+### Custom MATLAB Root
+
+Use the environment variable `MWI_CUSTOM_MATLAB_ROOT` to specify the location of `MATLAB_ROOT`.
+
+When this environment variable is set, `matlab-proxy` will not search the system PATH for MATLAB.
+
+This might be useful in the following situations:
+
+1. Changes to the system PATH are not possible or desirable.
+2. There are multiple MATLAB installations on a system, and you want to use `matlab-proxy` with a particular installation of MATLAB.
+3. The existing `matlab` executable on PATH is a user defined script as explained in this [issue](https://github.com/mathworks/matlab-proxy/issues/3).
+
+Example usage:
+```bash
+env MWI_CUSTOM_MATLAB_ROOT=/opt/software/matlab/r2023a matlab-proxy-app
+```
+
 
 
 ## Custom HTTP Headers 

matlab_proxy/app.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2020-2022 The MathWorks, Inc.
+# Copyright (c) 2020-2023 The MathWorks, Inc.
 
 import asyncio
 import json
@@ -19,7 +19,7 @@
 from matlab_proxy.util import list_servers, mwi
 from matlab_proxy.util.mwi import environment_variables as mwi_env
 from matlab_proxy.util.mwi import token_auth
-from matlab_proxy.util.mwi.exceptions import AppError, LicensingError, InvalidTokenError
+from matlab_proxy.util.mwi.exceptions import AppError, InvalidTokenError, LicensingError
 
 mimetypes.add_type("font/woff", ".woff")
 mimetypes.add_type("font/woff2", ".woff2")

matlab_proxy/constants.py

@@ -1,3 +1,5 @@
-"""This module defines project-level constants"""
+# Copyright (c) 2023 The MathWorks, Inc.
 
+"""This module defines project-level constants"""
 CONNECTOR_SECUREPORT_FILENAME = "connector.securePort"
+VERSION_INFO_FILE_NAME = "VersionInfo.xml"

matlab_proxy/settings.py

@@ -11,28 +11,68 @@
 from pathlib import Path
 
 import matlab_proxy
+from matlab_proxy.constants import VERSION_INFO_FILE_NAME
 from matlab_proxy.util import mwi, system
 from matlab_proxy.util.mwi import environment_variables as mwi_env
 from matlab_proxy.util.mwi import token_auth
 
 logger = mwi.logger.get()
 
 
-def get_matlab_path():
+def get_matlab_root_path():
+    """Returns the path from the MWI_CUSTOM_MATLAB_ROOT environment variable if valid, else returns
+    MATLAB root based on the matlab executable if found on the system path.
+
+    Returns:
+        pathlib.Path: pathlib.Path object to MATLAB root.
+    """
+    custom_matlab_root_path = os.environ.get(mwi_env.get_env_name_custom_matlab_root())
+
+    if custom_matlab_root_path and mwi.validators.validate_custom_matlab_root_path(
+        Path(custom_matlab_root_path)
+    ):
+        return custom_matlab_root_path
+
     which_matlab = shutil.which("matlab")
-    if which_matlab is None:
+
+    return Path(which_matlab).resolve().parent.parent if which_matlab else None
+
+
+def get_matlab_executable_path(matlab_root_path: Path):
+    """Returns path to the MATLAB executable based on the OS
+
+    Args:
+        matlab_root_path (Path): Path to MATLAB Root
+
+    Returns:
+        [Path | None]: Path to MATLAB executable if a valid MATLAB root path is supplied else return None
+    """
+    if not matlab_root_path:
         return None
-    return Path(which_matlab).resolve().parent.parent
+
+    return (
+        matlab_root_path / "bin" / "matlab"
+        if system.is_posix()
+        else matlab_root_path / "bin" / "matlab.exe"
+    )
 
 
-def get_matlab_version(matlab_path):
-    """Get the MATLAB Release version in this image"""
+def get_matlab_version(matlab_root_path):
+    """Returns MATLAB version from VersionInfo.xml file present at matlab_root_path
 
-    if matlab_path is None:
+    Args:
+        matlab_root_path (pathlib.Path): pathlib.Path to MATLAB root.
+
+    Returns:
+        (str | None): Returns MATLAB version from VersionInfo.xml file.
+    """
+    if matlab_root_path is None:
         return None
 
-    tree = ET.parse(matlab_path / "VersionInfo.xml")
+    version_info_file_path = Path(matlab_root_path) / VERSION_INFO_FILE_NAME
+    tree = ET.parse(version_info_file_path)
     root = tree.getroot()
+
     return root.find("release").text
 
 
@@ -137,7 +177,8 @@ def get(config_name=matlab_proxy.get_default_config_name(), dev=False):
         matlab_startup_file = str(
             Path(__file__).resolve().parent / "matlab" / "startup.m"
         )
-        matlab_path = get_matlab_path()
+        matlab_path = get_matlab_root_path()
+        matlab_executable_path = get_matlab_executable_path(Path(matlab_path))
         ws_env, ws_env_suffix = get_ws_env_settings()
 
         ssl_key_file, ssl_cert_file = mwi.validators.validate_ssl_key_and_cert_file(
@@ -172,7 +213,7 @@ def get(config_name=matlab_proxy.get_default_config_name(), dev=False):
             "matlab_path": matlab_path,
             "matlab_version": get_matlab_version(matlab_path),
             "matlab_cmd": [
-                "matlab",
+                matlab_executable_path,
                 "-nosplash",
                 flag_to_hide_desktop,
                 "-softwareopengl",

matlab_proxy/util/__init__.py

@@ -1,8 +1,9 @@
-# Copyright (c) 2020-2022 The MathWorks, Inc.
+# Copyright (c) 2020-2023 The MathWorks, Inc.
 import argparse
 import os
 import socket
-import sys
+
+from pathlib import Path
 
 import matlab_proxy
 from matlab_proxy.util import mwi, system
@@ -241,3 +242,16 @@ def get_access_url(app):
         url = f"{access_protocol}://{host_interface}:{port}{base_url}"
 
     return url
+
+
+def is_valid_path(path: Path):
+    """Returns true if path supplied is a valid path to a file or directory
+
+    Args:
+        path (pathlib.Path): pathlib.Path object of a file or directory
+
+    Returns:
+        bool: True if a valid path is supplied else False
+    """
+    path = Path(path)
+    return path.is_dir() or path.is_file()

matlab_proxy/util/mwi/environment_variables.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2020-2022 The MathWorks, Inc.
+# Copyright (c) 2020-2023 The MathWorks, Inc.
 """This file lists and exposes the environment variables which are used by the integration."""
 
 import os
@@ -145,3 +145,8 @@ def get_env_name_matlab_log_dir():
 def get_env_name_mwi_use_existing_license():
     """Returns the environment variable name used to instruct matlab-proxy to use an existing license. Usually used by already activated MATLAB installations."""
     return "MWI_USE_EXISTING_LICENSE"
+
+
+def get_env_name_custom_matlab_root():
+    """User specified path to MATLAB root"""
+    return "MWI_CUSTOM_MATLAB_ROOT"

matlab_proxy/util/mwi/validators.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2020-2022 The MathWorks, Inc.
+# Copyright (c) 2020-2023 The MathWorks, Inc.
 """This file contains validators for various runtime artefacts.
 A validator is defined as a function which verifies the input and 
 returns it unchanged if validation passes. 
@@ -14,15 +14,23 @@
 import os
 import socket
 import sys
+from pathlib import Path
+
+from typing import List
 
 import pkg_resources
 
 import matlab_proxy
+from matlab_proxy.constants import VERSION_INFO_FILE_NAME
 
 from . import environment_variables as mwi_env
 from matlab_proxy.util import system
 from . import logger as mwi_logger
 
+from matlab_proxy import util
+
+from .exceptions import MatlabError
+
 logger = mwi_logger.get()
 
 
@@ -276,3 +284,51 @@ def validate_use_existing_licensing(use_existing_license):
         bool: if use_existing_license is set to true
     """
     return True if use_existing_license.casefold() == "true" else False
+
+
+def validate_paths(paths: List[Path]):
+    """Validates if  paths of directories or files exists on the file system.
+
+    Args:
+        paths ([pathlib.Path]): List of pathlib.Path's to directories or files
+
+    Raises:
+        OSError: When an invalid path is supplied
+
+    Returns:
+        [pathlib.Path] | None: [pathlib.Path] if valid paths are supplied else None
+    """
+    for path in paths:
+        if not util.is_valid_path(path):
+            raise OSError(f"Supplied invalid path:{path}")
+
+    return paths
+
+
+def validate_custom_matlab_root_path(matlab_root: Path):
+    """Validate if path supplied is MATLAB_ROOT by checking for the existence of VersionInfo.xml file
+    at matlab_root
+
+    Args:
+        path (pathlib.Path): path to MATLAB root
+
+    Returns:
+        pathlib.Path | None: pathlib.Path if a valid path to MATLAB root is supplied else None
+    """
+    try:
+        matlab_root = matlab_root
+        validate_paths([matlab_root])
+        logger.debug(f"Supplied valid MATLAB root path:{matlab_root}")
+    except OSError as exc:
+        logger.error(". ".join(exc.args))
+        sys.exit(1)
+
+    version_info_file_path = matlab_root / VERSION_INFO_FILE_NAME
+
+    if not version_info_file_path.is_file():
+        logger.error(
+            f" {VERSION_INFO_FILE_NAME} file doesn't exist at the provided path :{matlab_root}"
+        )
+        sys.exit(1)
+
+    return matlab_root