feat(backend): Add container backend (#135)

pyproject.toml

@@ -56,6 +56,7 @@ dev = [
 "virtualenv" = "isolate.backends.virtualenv:VirtualPythonEnvironment"
 "conda" = "isolate.backends.conda:CondaEnvironment"
 "local" = "isolate.backends.local:LocalPythonEnvironment"
+"container" = "isolate.backends.container:ContainerizedPythonEnvironment"
 "isolate-server" = "isolate.backends.remote:IsolateServer"
 "pyenv" = "isolate.backends.pyenv:PyenvEnvironment"
 

src/isolate/backends/container.py

@@ -0,0 +1,49 @@
+from __future__ import annotations
+
+import sys
+from dataclasses import dataclass, field
+from pathlib import Path
+from typing import Any, ClassVar
+
+from isolate.backends import BaseEnvironment
+from isolate.backends.common import sha256_digest_of
+from isolate.backends.settings import DEFAULT_SETTINGS, IsolateSettings
+from isolate.connections import PythonIPC
+
+
+@dataclass
+class ContainerizedPythonEnvironment(BaseEnvironment[Path]):
+    BACKEND_NAME: ClassVar[str] = "container"
+
+    image: dict[str, Any] = field(default_factory=dict)
+    python_version: str | None = None
+    tags: list[str] = field(default_factory=list)
+
+    @classmethod
+    def from_config(
+        cls,
+        config: dict[str, Any],
+        settings: IsolateSettings = DEFAULT_SETTINGS,
+    ) -> BaseEnvironment:
+        environment = cls(**config)
+        environment.apply_settings(settings)
+        return environment
+
+    @property
+    def key(self) -> str:
+        # dockerfile_str is always there, but the validation is handled by the
+        # controller.
+        dockerfile_str = self.image.get("dockerfile_str", "")
+        return sha256_digest_of(dockerfile_str, *sorted(self.tags))
+
+    def create(self, *, force: bool = False) -> Path:
+        return Path(sys.exec_prefix)
+
+    def destroy(self, connection_key: Path) -> None:
+        raise NotImplementedError("ContainerizedPythonEnvironment cannot be destroyed")
+
+    def exists(self) -> bool:
+        return True
+
+    def open_connection(self, connection_key: Path) -> PythonIPC:
+        return PythonIPC(self, connection_key)