chore: Update gPRC documentation

doc/changelog.d/1469.maintenance.md

@@ -0,0 +1 @@
+Update gPRC documentation

doc/source/conf.py

@@ -118,6 +118,9 @@
 numpydoc_validation_exclude = {  # set of regex
     # grpc files
     r"\.*pb2\.*",
+    # Exclude built-in exception attributes from all exception classes
+    r".*__cause__$",
+    r".*__context__$",
 }
 
 # Favicon
@@ -230,7 +233,7 @@
     "show_breadcrumbs": True,
     "collapse_navigation": True,
     "use_edit_page_button": True,
-    "header_links_before_dropdown": 5,  # number of links before the dropdown menu
+    "header_links_before_dropdown": 6,  # number of links before the dropdown menu
     "additional_breadcrumbs": [
         ("PyAnsys", "https://docs.pyansys.com/"),
     ],

doc/source/index.rst

@@ -146,5 +146,6 @@ If you are not sure which mode to pick, see :doc:`getting_started/choose_your_mo
    API reference <api/ansys/mechanical/core/index>
    contribute
    faq
+   contribute
    kil/index
    changelog

doc/source/user_guide/remote_session/grpc_security.rst

@@ -3,11 +3,115 @@
 Secure gRPC connections
 =======================
 
-PyMechanical supports secure gRPC connections using mTLS, WNUA, or insecure modes.
+PyMechanical supports gRPC connections using mTLS, WNUA, or insecure modes.
 
-.. warning::
-   Secure connections (mTLS, WNUA) require specific service packs for each version.
-   Versions without the required service pack only support insecure mode.
+.. _transport_modes:
+
+Transport mode comparison
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. _mtls_mode:
+
+**mTLS (Mutual TLS)**
+
+Provides certificate-based mutual authentication and encryption. Both server and client must possess valid certificates signed by the same Certificate Authority (CA). This mode is platform-independent and recommended for production deployments requiring strong security.
+
+*Authentication mechanism:* Both parties validate each other's certificates against a trusted CA. The connection is rejected if either certificate is invalid or untrusted.
+
+*Encryption:* All data transmitted is encrypted using TLS protocol.
+
+*Cross-platform:* Works on Windows and Linux.
+
+*Network scope:* Can operate across any network including the internet, cloud deployments, and remote connections.
+
+.. _wnua_mode:
+
+**WNUA (Windows Named User Authentication)**
+
+Windows-only mode that authenticates using the current Windows user's credentials through SSPI/Negotiate protocol. Provides authentication based on Windows identity but does not encrypt the data channel.
+
+*Authentication mechanism:* The client authenticates as the currently logged-in Windows user. Only the same Windows user account can connect to the server, regardless of which machine they're connecting from within the domain/workgroup.
+
+*Encryption:* Authentication is secure, but the data channel is **not encrypted**.
+
+*Platform restriction:* Windows only. Both server and client must be Windows systems.
+
+*Network scope:* Limited to Windows domain/workgroup networks. Does not work across domain boundaries without proper trust relationships.
+
+*Access control:* Only the same Windows user who started the server can connect, even from different machines.
+
+.. _insecure_mode:
+
+**Insecure**
+
+Provides no authentication or encryption. Any client that can reach the network port can connect without credentials.
+
+*Authentication mechanism:* None. Any client can connect.
+
+*Encryption:* None. All data is transmitted in plaintext.
+
+*Security risk:* Suitable only for local development on trusted machines. Never use in production or on untrusted networks.
+
+.. _host_and_ip:
+
+Host binding
+^^^^^^^^^^^^
+
+The server's host address determines which network interfaces accept connections:
+
+- **127.0.0.1 (localhost)**: Listens only on loopback. Only same-machine clients can connect. Traffic never leaves the machine.
+
+- **0.0.0.0 (all interfaces)**: Listens on all network interfaces. Any client that can route to the machine can attempt connection, subject to transport mode authentication.
+
+- **Specific IP** (e.g., 192.168.1.100): Listens only on that interface. Only clients that can route to that specific IP can attempt connection.
+
+.. _ip_connectivity:
+
+Client connectivity by IP and transport mode
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+**Server on 0.0.0.0 (all interfaces):**
+
+- **mTLS**: Any client from any network with valid certificates can connect. Access controlled by certificate validation.
+- **WNUA**: Only same Windows user can connect, from same or different machines within domain/workgroup. Different users blocked.
+- **Insecure**: Anyone who can reach the port can connect. No restrictions. High security risk.
+
+**Server on 127.0.0.1 (localhost only):**
+
+- **mTLS**: Only local clients with valid certificates can connect.
+- **WNUA**: Only same Windows user on same machine can connect.
+- **Insecure**: Only local clients can connect. Relatively safe for development.
+
+**Server on specific IP:**
+
+- **mTLS**: Clients that can route to that IP with valid certificates can connect.
+- **WNUA**: Same Windows user from machines that can route to that IP can connect.
+- **Insecure**: Anyone who can route to that IP can connect. Security risk on shared networks.
+
+**Summary table:**
+
+.. list-table::
+   :header-rows: 1
+   :widths: 20 30 25 25
+
+   * - Transport Mode
+     - Authentication
+     - Encryption
+     - Connectivity Scope
+   * - mTLS
+     - Certificate-based
+     - Yes (TLS)
+     - Any network with valid certs
+   * - WNUA
+     - Windows user identity
+     - No
+     - Same Windows user only
+   * - Insecure
+     - None
+     - No
+     - Unrestricted (dangerous)
+
+See the table below for version-specific support and service pack requirements.
 
 .. _grpc_security_version_requirements:
 
@@ -47,25 +151,33 @@
      Ansys installation directory.
 
 .. warning::
-   **Breaking Change**: Version mismatch behavior
+   **Breaking Change for Linux Users**
+
+   If you have the **latest PyMechanical** with an **older version of Mechanical**
+   that doesn't support secure connections (pre-2024 R2 or without required service pack):
 
-   When using ``launch_mechanical()`` without explicitly specifying ``transport_mode``:
+   - **Linux**: The default transport mode is ``mtls``. Calling ``launch_mechanical()``
+     without explicitly specifying ``transport_mode="insecure"`` **will fail** because
+     old Mechanical versions don't support mtls.
 
-   - If you have a **newer version of PyMechanical** with an **older version of Mechanical**
-     that doesn't support secure connections, the connection fails.
-   - If you have an **older version of PyMechanical** with a **newer version of Mechanical**
-     that requires secure connections by default, the connection fails.
+   - **Windows**: The default transport mode is ``wnua``. A warning is issued and the
+     connection **automatically falls back to insecure mode**. The connection succeeds,
+     but you should explicitly specify ``transport_mode="insecure"`` to avoid the warning.
 
-   **Solution**: Always explicitly specify ``transport_mode`` to avoid compatibility issues:
+   **Required Action for Linux**: Always explicitly specify ``transport_mode="insecure"``
+   when using old Mechanical versions:
 
    .. code-block:: python
 
-      # For older Mechanical versions (241 or versions without required SP)
+      # Required for Mechanical 241 or versions without required SP
       mechanical = launch_mechanical(transport_mode="insecure")
 
-      # For newer Mechanical versions with secure support
-      mechanical = launch_mechanical(transport_mode="wnua")  # Windows
-      mechanical = launch_mechanical(transport_mode="mtls")  # Linux
+.. note::
+   **Forward Compatibility**
+
+   If you have an **older version of PyMechanical** with a **newer version of Mechanical**
+   that supports secure connections by default, you may need to update PyMechanical to
+   take advantage of secure transport modes.
 
 Transport modes
 ---------------
@@ -96,8 +208,8 @@
    - **Windows**: Set as a user-level environment variable only. System-level variables are ignored.
    - **Linux**: Can be set at any level (user or system).
 
-   When this variable is set and ``certs_dir`` is not explicitly specified, PyMechanical uses
-   the path from this environment variable.
+   When this variable is set and ``certs_dir`` is not explicitly specified, PyMechanical
+   uses the path from this environment variable.
 
    Example (Windows PowerShell):
 

src/ansys/mechanical/core/__init__.py

@@ -41,7 +41,7 @@
 
 from ansys.mechanical.core.logging import Logger
 
-LOG = Logger(level=logging.ERROR, to_file=False, to_stdout=True)
+LOG = Logger(level=logging.WARN, to_file=False, to_stdout=True)
 """Create logger for package level use."""
 
 

src/ansys/mechanical/core/embedding/find_mechanical.py

@@ -60,8 +60,8 @@ def cli(version: int, path: str | None = None) -> tuple[int, str]:
         Optional path to the Ansys installation directory.
         eg: "usr/ansys_inc/v251/"
 
-    Example
-    -------
+    Examples
+    --------
     Get the version and location of the installation directory.
 
     >>> find-mechanical -r 251

src/ansys/mechanical/core/embedding/logger/__init__.py

@@ -24,21 +24,21 @@
 
 Module to interact with the built-in logging system of Mechanical.
 
-Usage
------
-
+Examples
+--------
 Configuring logger
 ~~~~~~~~~~~~~~~~~~
 
 Configuring the logger can be done using the
 :class:`Configuration <ansys.mechanical.core.embedding.logger.Configuration>` class:
 
 .. code:: python
-  import ansys.mechanical.core as mech
-  from ansys.mechanical.core.embedding.logger import Configuration, Logger
 
-  Configuration.configure(level=logging.INFO, to_stdout=True, base_directory=None)
-  app = mech.App(version=252)
+   import ansys.mechanical.core as mech
+   from ansys.mechanical.core.embedding.logger import Configuration, Logger
+
+   Configuration.configure(level=logging.INFO, to_stdout=True, base_directory=None)
+   app = mech.App(version=252)
 
 Then, the :class:`Logger <ansys.mechanical.core.embedding.logger.Logger>` class can
 be used to write messages to the log:

src/ansys/mechanical/core/embedding/transaction.py

@@ -26,8 +26,8 @@ class Transaction:  # When ansys-pythonnet issue #14 is fixed, this class will b
     """
     A class to speed up bulk user interactions using Ansys ACT Mechanical Transaction.
 
-    Example
-    -------
+    Examples
+    --------
     >>> with Transaction() as transaction:
     ...     pass  # Perform bulk user interactions here
     """

src/ansys/mechanical/core/ide_config.py

@@ -270,8 +270,8 @@ def cli(ide: str, target: str, revision: int) -> None:
         The Mechanical revision number. For example, "261".
         If unspecified, it finds the default Mechanical version from ansys-tools-path.
 
-    Usage
-    -----
+    Examples
+    --------
     The following example demonstrates the main use of this tool:
 
         $ ansys-mechanical-ideconfig --ide vscode --target user --revision 261

src/ansys/mechanical/core/launcher.py

@@ -37,6 +37,7 @@
     has_grpc_service_pack,
     is_linux,
     resolve_certs_dir,
+    verify_server_certificates,
 )
 
 
@@ -101,8 +102,12 @@ def __init__(
             else:
                 transport_mode = "wnua"
         self.transport_mode = transport_mode
+
         # Resolve certs_dir using environment variable if needed for mTLS
         self.certs_dir = resolve_certs_dir(transport_mode, certs_dir)
+        if transport_mode.lower() == "mtls":
+            # Check that certs exist if needed for mTLS
+            verify_server_certificates(self.certs_dir)
         self.__ui_arg_list = ["-DSApplet", "-nosplash", "-notabctrl"]
         self.__batch_arg_list = ["-DSApplet", "-b"]
 
@@ -210,10 +215,11 @@ def __get_commandline_args(self):
 
         # Validate transport mode requirements
         if not supports_grpc and self.transport_mode.lower() != "insecure":
-            raise Exception(
+            LOG.warning(
                 f"Mechanical version {version} does not support secure transport modes. "
-                f"{get_service_pack_message(version)}"
-                f" Please refer to the documentation for more details."
+                f"{get_service_pack_message(version)} "
+                f"Using INSECURE transport mode instead. "
+                f"Please refer to the documentation for more details. "
                 f"https://mechanical.docs.pyansys.com/version/stable/user_guide/remote_session/grpc_security.html"
             )
 

src/ansys/mechanical/core/mechanical.py

@@ -265,9 +265,8 @@ def get_mechanical_path(allow_input=True):
 def check_valid_mechanical():
     """Change to see if the default Mechanical path is valid.
 
-    Example (windows)
-    -----------------
-
+    Examples
+    --------
     >>> from ansys.mechanical.core import mechanical
     >>> from ansys.tools.common.path import change_default_mechanical_path
     >>> mechanical_path = "C:/Program Files/ANSYS Inc/v261/aisol/bin/winx64/AnsysWBU.exe"

src/ansys/mechanical/core/misc.py

@@ -42,6 +42,16 @@ def is_windows():
     return False
 
 
+def is_linux() -> bool:
+    """Check if the host machine is Linux.
+
+    Returns
+    -------
+    ``True`` if the host machine is Linux, ``False`` otherwise.
+    """
+    return os.name == "posix"
+
+
 def get_mechanical_bin(release_version):
     """Get the path for the Mechanical executable file based on the release version.
 
@@ -303,16 +313,6 @@ def get_service_pack_message(version):
         return "Update to Ansys 2024 R2 or later for secure gRPC support."
 
 
-def is_linux() -> bool:
-    """Check if the host machine is Linux.
-
-    Returns
-    -------
-    ``True`` if the host machine is Linux, ``False`` otherwise.
-    """
-    return os.name == "posix"
-
-
 def resolve_certs_dir(transport_mode, certs_dir=None):
     """Resolve the certificate directory for mTLS connections.
 
@@ -355,3 +355,31 @@ def resolve_certs_dir(transport_mode, certs_dir=None):
             # On Linux, read at any level
             return os.environ.get("ANSYS_GRPC_CERTIFICATES", "certs")
     return certs_dir if certs_dir is not None else "certs"
+
+
+def verify_server_certificates(certs_dir: str) -> None:
+    """Check if the required server certificate files exist in the specified directory.
+
+    Parameters
+    ----------
+    certs_dir : str
+        Directory path where the certificate files are expected.
+
+    Raises
+    ------
+    FileNotFoundError
+        If any of the required certificate files are missing.
+    """
+    required_files_server = ["server.cert", "server.key", "ca.cert"]
+    missing_files = []
+    for filename in required_files_server:
+        file_path = Path(certs_dir) / filename
+        if not file_path.is_file():
+            missing_files.append(filename)
+
+    if missing_files:
+        missing_str = ", ".join(missing_files)
+        raise FileNotFoundError(
+            f"Could not launch Ansys Mechanical in mtls transport mode. "
+            f"The following certificate files are missing in '{certs_dir}': {missing_str}"
+        )