podkit 0.3.1

Container management library with backend abstraction for sandboxed execution

Podkit - Simple Container Management Library

A Python library for sandboxed execution in Docker containers with backend abstraction (Kubernetes-ready)

Features

Podkit implements a clean three-layer architecture for flexible container management:

Layer 1 (Backend) provides runtime-agnostic infrastructure operations for Docker/Kubernetes with image management and workload execution;

Layer 2 (ContainerManager) bridges infrastructure and application logic with container lifecycle management, project-specific mounting strategies, and host-to-container path translation;

Layer 3 (SessionManager) delivers the user-facing API with session lifecycle tracking, automatic activity monitoring, and cleanup of expired sessions.

This separation enables backend portability (swap Docker for Kubernetes without touching business logic), customizable project configurations (different mounting strategies per project), and independent testing of each layer.

Example 1 (the simplest one)

# Auto-creates session OR reconnects to the existing running/exited container (auto-stopping after 1 min)

from podkit import get_docker_session

result = get_docker_session(user_id="bob", session_id="123").execute_command("pwd")
print(result.stdout)

# No auto-removing in this case, only auto-stopping!
# You may not close the session if you expect running some commands in this session again.
# Otherwise close the session manually, like in example 3.

Example 2 (simple with auto-cleanup)

# auto-cleanup with context manager (container will be removed, slower than example 1)

from podkit import get_docker_session

with get_docker_session(user_id="bob", session_id="123") as session:
    result = session.execute_command("pwd")
    print(result.stdout)

# Perfect when you need one-time execution - run the command and clean up resources right away

Example 3 (simple with mounts)

# Persistent workspace (host dir mapping)

from pathlib import Path
from podkit import get_docker_session

session = get_docker_session(
    user_id="bob",
    session_id="123",
    workspace="/app/data/workspace",
    workspace_host="./data/workspace" # files will be here on the host once container exits
)
session.write_file(Path("/workspace/data.txt"), "persistent data")
session.close()

Example 4 (full control - for advanced use cases)

Note: This example shows the low-level API for maximum control. For most use cases, use get_docker_session() instead.

from pathlib import Path

from podkit.backends.docker import DockerBackend
from podkit.core.manager import BaseContainerManager
from podkit.core.models import ContainerConfig
from podkit.core.session import BaseSessionManager
from podkit.utils.paths import get_workspace_path, write_to_mounted_path

# You must provide concrete ContainerManager implementation
# BaseContainerManager requires implementing get_mounts() and write_file()
class MyContainerManager(BaseContainerManager):
    """Custom container manager with project-specific mount logic."""

    def get_mounts(self, user_id: str, session_id: str, config: ContainerConfig):
        """Define how exactly to mount volumes."""

        workspace_path = get_workspace_path(self.workspace_base, user_id, session_id)
        workspace_path.mkdir(parents=True, exist_ok=True)

        return [{
            "Type": "bind",
            "Source": str(workspace_path),
            "Target": "/workspace",
        }]

    def write_file(self, container_id, container_path, content, user_id, session_id):
        """Write file to mounted filesystem (persists)."""

        return write_to_mounted_path(
            container_path,
            content,
            lambda path: self.to_host_path(path, user_id, session_id),
        )

backend = DockerBackend()
backend.connect()

container_manager = MyContainerManager(
    backend=backend,
    container_prefix="podkit",
    workspace_base=Path("/tmp/podkit_workspace"),
)

session_manager = BaseSessionManager(
    container_manager=container_manager,
    default_image="python:3.15-rc-alpine3.23",
)

# Configuration with auto-shutdown (entrypoint=None, default behavior)
# Container runs for 5 minutes then auto-exits (via sleep command)
sandbox_config = ContainerConfig(
    image="python:3.15-rc-alpine3.23",
    container_lifetime_seconds=300,  # Container auto-exits after 5 minutes
    cpu_limit=1.0,
    memory_limit="512m",
    environment={
        "PYTHONUNBUFFERED": "1",
        "LOG_LEVEL": "DEBUG",
    },
)

session = session_manager.create_session(
    user_id="user",
    session_id="session",
    config=sandbox_config,
)

# Execute commands - if container exited (timeout), it auto-restarts
result = session_manager.execute_command(
    user_id="user",
    session_id="session",
    command=["sh", "-c", "echo 'Hello'"],
)
print(result.stdout)

session_manager.write_file(
    user_id="user",
    session_id="session",
    container_path=Path("/workspace/file.txt"),
    content="Hello from podkit",
)

# Configuration without auto-shutdown (explicit entrypoint disables it)
# When entrypoint=[] is set, container uses "sleep infinity" and runs until manually closed
# Note: container_lifetime_seconds is IGNORED when explicit entrypoint is set
no_timeout_config = ContainerConfig(
    image="python:3.15-rc-alpine3.23",
    entrypoint=[],  # Explicit empty entrypoint = sleep infinity, no auto-shutdown
)

session2 = session_manager.create_session(
    user_id="user2",
    session_id="session2",
    config=no_timeout_config,
)
# This container runs indefinitely until manually closed (below)
# Session may still expire due to inactivity (controlled by session_inactivity_timeout_seconds)

# Cleanup
session_manager.close_session("user", "session")
session_manager.close_session("user2", "session2")

Development Setup

Prerequisites

• Docker
• uv

Installation

./scripts/install.sh

Running Tests

Integration Tests (Recommended)

Run tests in Docker container (most realistic):

./scripts/test.sh

This will:

1. Build the test runner container with all dependencies
2. Mount the Docker socket and test workspace
3. Run pytest with the integration tests
4. Clean up automatically

Local Testing (Development)

For faster iteration during development:

# Start test container and keep it running
docker-compose run --rm test-runner bash

# Inside the container, run tests
pytest tests/integration/test_integration_happy_path.py -v

# Or run specific tests
pytest tests/integration/test_integration_happy_path.py::TestPodkitIntegrationHappyPath::test_01_backend_initialized -v

Linting

./scripts/lint.sh         # Check only
./scripts/lint.sh --fix   # Auto-fix issues

This runs ruff and pylint for code checking and formatting.