Mitogen

0.3.46 · active · verified Fri Apr 17

Mitogen is a library for writing distributed self-replicating programs, designed to be fast, efficient, and flexible. It enables code execution on remote hosts with minimal overhead, making it ideal for automation and orchestration tasks. The current version is 0.3.46, and it sees regular minor releases, typically every few weeks or months, indicating active development.

Common errors

```
AttributeError: 'Router' object has no attribute 'importer_whitelist'
```
cause Attempting to access or set the deprecated `importer_whitelist` (or `importer_blacklist`) attribute on a `Router` instance.

fix The `importer_whitelist` attribute was removed in Mitogen v0.3.42. Use `mitogen.master.ImportPolicy` instead, which is passed as an argument to the `Router` constructor. Example: `policy = mitogen.master.ImportPolicy(overrides={'mypackage': True}); router = mitogen.master.Router(import_policy=policy)`.
```
mitogen.parent.ModuleDeniedByOverridesError: Refused to import module 'your_module_name'
```
cause A module required by remote code is not explicitly allowed by the `ImportPolicy` configured on the Mitogen router, often after upgrading to v0.3.42 or later.

fix Configure your `mitogen.master.ImportPolicy` to explicitly allow the module. For example, if 'your_module_name' is denied: `policy = mitogen.master.ImportPolicy(overrides={'your_module_name': True}); router = mitogen.master.Router(import_policy=policy)`. Remember to restart the router for changes to take effect.

Warnings

breaking The `Importer` class and its `whitelist`/`blacklist` methods for controlling remote imports were removed in v00.3.42. Direct manipulation of `Router.importer_whitelist` or `Router.importer_blacklist` is no longer supported.
Fix: Migrate to `mitogen.master.ImportPolicy`. Construct an `ImportPolicy` object with `overrides` or `blocks` and pass it to the `Router` constructor via the `import_policy` argument. E.g., `policy = ImportPolicy(overrides={'mypackage': True}); router = Router(import_policy=policy)`.
gotcha Mitogen's internal logging configuration was overhauled in v0.3.45. If your application relied on specific default logging behaviors or internal Mitogen loggers, you might observe changes in log output or levels.
Fix: Review the Mitogen logging documentation and explicitly configure your `logging` module settings (e.g., `logging.basicConfig`) to ensure desired behavior. For Ansible integration, note that Mitogen debugging is hidden by default at high Ansible verbosity levels.
gotcha Improved security in v0.3.41 introduced a default deny policy for `Unpickler GLOBAL` opcodes, restricting what types can be unpickled over the network. This prevents deserialization of potentially arbitrary code.
Fix: If you encounter pickling errors for custom types, ensure they are explicitly allowed or refactor your code to avoid relying on implicit `GLOBAL` opcodes for insecure types. Consider using `mitogen.master.ImportPolicy` to manage allowed types for unpickling if custom unpickling is necessary and safe.

Install

pip install mitogen Install Mitogen

Imports

Router
```
from mitogen.master import Router
```
ImportPolicy
wrong:
```
from mitogen.master import Importer
```
correct:
```
from mitogen.master import ImportPolicy
```
Importer class and its whitelist/blacklist methods were removed in v0.3.42. Use ImportPolicy instead.

Quickstart

This example demonstrates how to connect to a remote host (defaulting to localhost via SSH) and execute a simple Python function, returning its result. Ensure SSH is configured for the target host or choose a different transport (e.g., `router.fork()`).

import mitogen.master
import os
import sys
import logging

logging.basicConfig(level=logging.INFO)

# Connect to a remote host via SSH. For local testing, set MITOGEN_TARGET_HOSTNAME='localhost'
# or configure your SSH client to allow localhost connections without password.
router = mitogen.master.Router()

try:
    hostname = os.environ.get('MITOGEN_TARGET_HOSTNAME', 'localhost')
    if hostname == 'localhost' and not os.path.exists(os.path.expanduser('~/.ssh/id_rsa')):
        logging.warning("No SSH key found for 'localhost'. Ensure SSH access is configured or use a different transport.")

    context = router.ssh(hostname=hostname)

    # Run an operation on the remote host.
    res = context.call(lambda: 'Hello from Python %s on %s' % (sys.version, os.uname()[1]))

    # Print its return value.
    print(f"Remote execution result: {res}")

finally:
    router.shutdown()
    router.join()

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