feat: support setting the pythonpath in configuration YAMLs

CHANGES.rst

@@ -48,6 +48,9 @@ New Features in 24.0
 - The pyproject.toml gained a config for `ruff <https://github.com/astral-sh/ruff>`_.
 - ``setuptools_scm`` is now used to generate a version file.
 - labgrid-client console will fallback to telnet if microcom is not available.
+- The ``pythonpath`` key allows specifying additional directories for the
+  Python search path (sys.path). This helps include modules/packages not
+  in the standard library or current directory.
 
 
 Bug fixes in 24.0

doc/configuration.rst

@@ -3555,6 +3555,8 @@ The skeleton for an environment consists of:
    imports:
      - <import.py>
      - <python module>
+   pythonpath:
+     - <absolute or relative path>
 
 If you have a single target in your environment, name it "main", as the
 ``get_target`` function defaults to "main".

labgrid/config.py

@@ -3,13 +3,15 @@
 This class encapsulates access functions to the environment configuration
 
 """
+from typing import List
 import os
 from yaml import YAMLError
 import attr
 
 from .exceptions import NoConfigFoundError, InvalidConfigError
 from .util.yaml import load, resolve_templates
 
+
 @attr.s(eq=False)
 class Config:
     filename = attr.ib(validator=attr.validators.instance_of(str))
@@ -258,6 +260,12 @@ def get_imports(self):
 
         return imports
 
+    def get_pythonpath(self) -> List[str]:
+        configured_pythonpath = self.data.get('pythonpath', [])
+        if not isinstance(configured_pythonpath, list):
+            raise KeyError("pythonpath needs to be a list")
+        return [self.resolve_path(p) for p in configured_pythonpath]
+
     def get_paths(self):
         """Helper function that returns the subdict of all paths
 

labgrid/environment.py

@@ -1,5 +1,8 @@
-import os
 from typing import Optional
+from importlib.machinery import SourceFileLoader
+import importlib.util
+import os
+import sys
 import attr
 
 from .target import Target
@@ -19,11 +22,12 @@ def __attrs_post_init__(self):
 
         self.config = Config(self.config_file)
 
-        for user_import in self.config.get_imports():
-            import importlib.util
-            from importlib.machinery import SourceFileLoader
-            import sys
+        # we want configured paths to appear at the beginning of the
+        # PYTHONPATH, so they need to be inserted in reverse order
+        for user_pythonpath in reversed(self.config.get_pythonpath()):
+            sys.path.insert(0, user_pythonpath)
 
+        for user_import in self.config.get_imports():
             if user_import.endswith('.py'):
                 module_name = os.path.basename(user_import)[:-3]
                 loader = SourceFileLoader(module_name, user_import)

man/labgrid-device-config.5

@@ -204,6 +204,29 @@ imports:
 .fi
 .UNINDENT
 .UNINDENT
+.SH PYTHONPATH
+.sp
+The \fBpythonpath\fP key allows specifying additional directories to be added
+to the Python search path (sys.path). This is particularly useful for
+including directories that contain Python modules and packages which are
+not installed in the standard library or not in the current directory.
+Relative paths are resolved relative to the configuration file\(aqs location.
+Specifying this option enables the environment to locate and import modules
+that are not in the default Python path.
+.SS PYTHONPATH EXAMPLE
+.sp
+Extend the Python search path to include the \fIlibs\fP directory:
+.INDENT 0.0
+.INDENT 3.5
+.sp
+.nf
+.ft C
+pythonpath:
+  \- libs
+.ft P
+.fi
+.UNINDENT
+.UNINDENT
 .SH EXAMPLES
 .sp
 A sample configuration with one \fImain\fP target, accessible via SerialPort

man/labgrid-device-config.rst

@@ -192,6 +192,25 @@ Import a local `myfunctions.py` file:
    imports:
      - myfunctions.py
 
+PYTHONPATH
+----------
+The ``pythonpath`` key allows specifying additional directories to be added
+to the Python search path (sys.path). This is particularly useful for
+including directories that contain Python modules and packages which are
+not installed in the standard library or not in the current directory.
+Relative paths are resolved relative to the configuration file's location.
+Specifying this option enables the environment to locate and import modules
+that are not in the default Python path.
+
+PYTHONPATH EXAMPLE
+~~~~~~~~~~~~~~~~~~
+Extend the Python search path to include the `libs` directory:
+
+::
+
+   pythonpath:
+     - libs
+
 EXAMPLES
 --------
 A sample configuration with one `main` target, accessible via SerialPort

tests/test_environment.py

@@ -1,3 +1,4 @@
+from pathlib import Path
 import pytest
 import warnings
 
@@ -81,6 +82,36 @@ class Test:
         t = myimport.Test()
         assert (isinstance(t, myimport.Test))
 
+    def test_env_pythonpath_yaml(self, tmp_path: Path):
+        config = tmp_path / "configs" / "config.yaml"
+        config.parent.mkdir(parents=True, exist_ok=True)
+        config.write_text(f"""---
+target:
+  main:
+    drivers: {{}}
+pythonpath:
+  - ../modules
+imports:
+  - ../sample.py
+""")
+        sample_py = tmp_path / "sample.py"
+        sample_py.write_text("""
+from some_module import Foo
+""")
+        some_module = tmp_path / "modules" / "some_module.py"
+        some_module.parent.mkdir(parents=True, exist_ok=True)
+        some_module.write_text("""
+class Foo:
+    pass
+""")
+        e = Environment(str(config))
+        assert isinstance(e, Environment)
+        import sys
+        assert 'some_module' in sys.modules
+        import some_module
+        f = some_module.Foo()
+        assert isinstance(f, some_module.Foo)
+
     def test_create_named_resources(self, tmpdir):
         p = tmpdir.join("config.yaml")
         p.write(