Merge branch 'conda-clash'

This prevents problematic environment variables from propagating to
the worker process, to avoid the wrong Python environment being used.

See:
https://imagesc.zulipchat.com/#narrow/channel/377693-Appose/topic/Python.20worker.20runs.20in.20wrong.20environment/with/583449746

Author: ctrueden

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "appose"
-version = "0.11.1.dev0"
+version = "0.12.0.dev0"
 description = "Appose: multi-language interprocess cooperation with shared memory."
 license = "BSD-2-Clause"
 authors = [{name = "Appose developers"}]

src/appose/environment.py

@@ -146,7 +146,22 @@ def python(self, *args) -> Service:
             "-c",
             "import appose.python_worker; appose.python_worker.main()",
         ]
-        return self.service(python_exes, *python_args).syntax(PythonSyntax())
+        # NB: Unset conda/mamba variables so they don't bleed into the worker
+        # process and cause the wrong Python interpreter to be resolved.
+        # Only clear variables not explicitly set by the caller via env().
+        conda_vars = (
+            "CONDA_PREFIX",
+            "CONDA_DEFAULT_ENV",
+            "CONDA_SHLVL",
+            "PYTHONEXECUTABLE",
+        )
+        explicit = self.env_vars()
+        conda_unset = {var: None for var in conda_vars if var not in explicit}
+        return (
+            self.service(python_exes, *python_args)
+            .syntax(PythonSyntax())
+            .env(**conda_unset)
+        )
 
     def groovy(
         self,

src/appose/service.py

@@ -47,10 +47,12 @@ class Service:
     _service_count: int = 0
 
     def __init__(
-        self, cwd: str | Path, env_vars: dict[str, str] | None = None, *args: str
+        self, cwd: str | Path, env_vars: dict[str, str | None] | None = None, *args: str
     ) -> None:
         self._cwd: Path = Path(cwd)
-        self._env_vars: dict[str, str] = env_vars.copy() if env_vars is not None else {}
+        self._env_vars: dict[str, str | None] = (
+            env_vars.copy() if env_vars is not None else {}
+        )
         self._args: list[str] = list(args)
         self._tasks: dict[str, "Task"] = {}
         self._service_id: int = Service._service_count
@@ -102,6 +104,20 @@ def init(self, script: str) -> "Service":
         self._init_script = script
         return self
 
+    def env(self, **vars: str | None) -> "Service":
+        """
+        Set environment variables to pass to the worker process.
+
+        Args:
+            **vars: Key/value pairs to add to the worker's environment.
+                A value of None causes the variable to be unset in the worker.
+
+        Returns:
+            This service object, for chaining method calls.
+        """
+        self._env_vars.update(vars)
+        return self
+
     def start(self) -> "Service":
         """
         Explicitly launch the worker process associated with this service.

src/appose/util/process.py

@@ -33,7 +33,11 @@ def builder(
     """
     env = os.environ.copy()
     if env_vars:
-        env.update(env_vars)
+        for key, value in env_vars.items():
+            if value is None:
+                env.pop(key, None)
+            else:
+                env[key] = value
 
     cwd = str(working_dir) if working_dir else None