Make mpi4py optional

README.md

@@ -52,7 +52,10 @@ or directly from GitHub:
 ```sh
 python -m pip install "optimas[all] @ git+https://github.com/optimas-org/optimas.git"
 ```
-Make sure `mpi4py` is available in your environment before installing optimas. For more details, check out the full [installation guide](https://optimas.readthedocs.io/en/latest/user_guide/installation_local.html). We have also prepared dedicated installation instructions for some HPC systems such as
+
+If you intend to run Optimus with an MPI Runner, make sure `mpi4py` is available in your environment before installing optimas.
+
+For more details, check out the full [installation guide](https://optimas.readthedocs.io/en/latest/user_guide/installation_local.html). We have also prepared dedicated installation instructions for some HPC systems such as
 [JUWELS (JSC)](https://optimas.readthedocs.io/en/latest/user_guide/installation_juwels.html),
 [Maxwell (DESY)](https://optimas.readthedocs.io/en/latest/user_guide/installation_maxwell.html) and
 [Perlmutter (NERSC)](https://optimas.readthedocs.io/en/latest/user_guide/installation_perlmutter.html).

doc/source/user_guide/dependencies.rst

@@ -7,11 +7,13 @@ Optimas relies on the following packages:
 
 * `jinja2 <https://pypi.org/project/jinja2/>`_ - Needed to generate simulation scripts from templates.
 * `libEnsemble <https://pypi.org/project/libensemble/>`_ - The backbone of optimas, orchestrates the concurrent evaluation of simulations, the resource detection and allocation, and the communication between simulations and manager.
-* `mpi4py <https://pypi.org/project/mpi4py/>`_ - Python bindings for MPI. Required for launching parallel simulations.
 * `pandas <https://pypi.org/project/pandas/>`_ - Enable output as pandas DataFrames.
 * `pydantic <https://pypi.org/project/pydantic/>`_ - Input validation and object serialization.
 * (optional) `Ax <https://pypi.org/project/ax-platform/>`_ - Algorithms for Bayesian optimization.
 
+Optional dependencies:
+
+* `mpi4py <https://pypi.org/project/mpi4py/>`_ - Python bindings for MPI. Required for launching parallel simulations.
 
 The installed dependencies will determine which generators are available for use.
 See table below for a summary.

doc/source/user_guide/installation_local.rst

@@ -3,6 +3,8 @@ Installation on a local computer
 
 The recommended approach is to install optimas in a ``conda`` environment.
 
+Optional: If you intend to run Optimus with an MPI Runner, ``mpi4py`` is required.
+
 Install ``mpi4py``
 ~~~~~~~~~~~~~~~~~~
 If your system has already an MPI implementation installed, install ``mpi4py``

pyproject.toml

@@ -24,7 +24,6 @@ dependencies = [
     'libensemble >= 1.3.0',
     'jinja2',
     'pandas',
-    'mpi4py',
     'pydantic >= 2.0',
 ]
 dynamic = ['version']
@@ -36,10 +35,12 @@ test = [
     'pytest-mpi',
     'ax-platform >=0.5.0',
     'matplotlib',
+    'mpi4py',
 ]
 all = [
     'ax-platform >=0.5.0',
-    'matplotlib'
+    'matplotlib',
+    'mpi4py',
 ]
 
 [project.urls]