Allowing passing IP to MapdlPool (#3048)

* Allowing passing IP to MapdlPool

* add docs

* Fix vale

* Using ports

---------

Co-authored-by: Camille <78221213+clatapie@users.noreply.github.com>

doc/source/user_guide/pool.rst

@@ -41,6 +41,13 @@ their ports when creating the pool.
     'MAPDL Pool with 5 active instances'
     >>> pool.exit(block=True)
 
+You can also specify a list of IP addresses to connect to: 
+
+.. code:: pycon
+
+    >>> pool = MapdlPool(ip=["127.0.0.2", "127.0.0.3", "127.0.0.4"])
+    Creating Pool: 100%|########| 3/3 [00:01<00:00,  1.43it/s]
+
 You can access each individual MAPDL instance with this code:
 
 .. code:: pycon

src/ansys/mapdl/core/launcher.py

@@ -1170,7 +1170,7 @@ def launch_mapdl(
         override the default behavior of this keyword argument with
         the environment variable ``PYMAPDL_START_INSTANCE=FALSE``.
 
-    ip : bool, optional
+    ip : str, optional
         Used only when ``start_instance`` is ``False``. If provided,
         and ``start_instance`` (or its correspondent environment variable
         ``PYMAPDL_START_INSTANCE``) is ``True`` then, an exception is raised.

src/ansys/mapdl/core/pool.py

@@ -23,6 +23,7 @@
 """This module is for threaded implementations of the mapdl interface"""
 import os
 import shutil
+import socket
 import tempfile
 import time
 from typing import Any, Dict, List, Optional, Union
@@ -32,7 +33,9 @@
 from ansys.mapdl.core import LOG, launch_mapdl
 from ansys.mapdl.core.errors import MapdlRuntimeError, VersionError
 from ansys.mapdl.core.launcher import (
+    LOCALHOST,
     MAPDL_DEFAULT_PORT,
+    check_valid_ip,
     get_start_instance,
     port_in_use,
 )
@@ -173,11 +176,15 @@ def __init__(
         override=True,
         start_instance: bool = None,
         exec_file: Optional[str] = None,
+        ip: Optional[str] = None,
         **kwargs,
     ) -> None:
         """Initialize several instances of mapdl"""
         self._instances: List[None] = []
 
+        # Getting debug arguments
+        _debug_no_launch = kwargs.pop("_debug_no_launch", None)
+
         if run_location is None:
             run_location = tempfile.gettempdir()
         self._root_dir: str = run_location
@@ -189,8 +196,40 @@ def __init__(
         self._exiting_i: int = 0
         self._override = override
 
-        # Getting start_instance
-        start_instance = get_start_instance(start_instance)
+        # Getting IP from env var
+        ip_env_var = os.environ.get("PYMAPDL_IP", "")
+        if ip_env_var != "":
+            if ip:
+                warnings.warn(
+                    "The env var 'PYMAPDL_IP' is set, hence the 'ip' argument is overwritten."
+                )
+
+            ip = ip_env_var
+            LOG.debug(f"An IP ({ip}) has been set using 'PYMAPDL_IP' env var.")
+
+        ip = None if ip == "" else ip  # Making sure the variable is not empty
+
+        if ip is None:
+            ips = LOCALHOST
+
+        else:
+            if not isinstance(ip, (tuple, list)):
+                ips = [ip]
+            else:
+                ips = ip
+
+            # Converting ip or hostname to ip
+            ips = [socket.gethostbyname(each) for each in ips]
+            _ = [check_valid_ip(each) for each in ips]  # double check
+
+        # Getting "start_instance" using "True" as default.
+        if (ip is not None) and (start_instance is None):
+            # An IP has been supplied. By default, 'start_instance' is equal
+            # false, unless it is set through the env vars.
+            start_instance = get_start_instance(start_instance=False)
+        else:
+            start_instance = get_start_instance(start_instance=start_instance)
+
         self._start_instance = start_instance
         LOG.debug(f"'start_instance' equals to '{start_instance}'")
 
@@ -257,6 +296,15 @@ def __init__(
             raise ValueError(
                 "The number of instances should be the same as the number of ports."
             )
+
+        if ips == LOCALHOST:
+            ips = [LOCALHOST for each in ports]
+
+        if len(ports) != len(ips):
+            raise ValueError(
+                "The number of ips should be the same as the number of ports."
+            )
+
         LOG.debug(f"Using ports: {ports}")
 
         self._instances = []
@@ -280,6 +328,17 @@ def __init__(
         self._instances = [None for _ in range(n_instances)]
 
         # threaded spawn
+        if _debug_no_launch:
+            self._debug_no_launch = {
+                "ports": ports,
+                "ips": ips,
+                "names": self._names,
+                "start_instance": start_instance,
+                "exec_file": exec_file,
+                "n_instances": n_instances,
+            }
+            return
+
         threads = [
             self._spawn_mapdl(
                 i,

tests/test_pool.py

@@ -337,6 +337,28 @@ def test_only_one_instance():
     pool.exit()
 
 
+def test_ip(monkeypatch):
+    monkeypatch.delenv("PYMAPDL_START_INSTANCE", raising=False)
+    monkeypatch.delenv("PYMAPDL_IP", raising=False)
+
+    ips = ["127.0.0.1", "127.0.0.2", "127.0.0.3"]
+    ports = [50083, 50100, 50898]
+    pool_ = MapdlPool(
+        3,
+        ip=ips,
+        port=ports,
+        exec_file=EXEC_FILE,
+        nproc=NPROC,
+        additional_switches=QUICK_LAUNCH_SWITCHES,
+        _debug_no_launch=True,
+    )
+    args = pool_._debug_no_launch
+
+    assert not args["start_instance"]  # Because of ip
+    assert args["ips"] == ips
+    assert args["ports"] == ports
+
+
 def test_next(pool):
     # Check the instances are free
     for each_instance in pool: