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mitogen/docs/api.rst

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API Reference
*************
Package Layout
==============
mitogen Package
---------------
.. automodule:: mitogen
.. autodata:: mitogen.__version__
.. autodata:: mitogen.is_master
.. autodata:: mitogen.context_id
.. autodata:: mitogen.parent_id
.. autodata:: mitogen.parent_ids
.. autofunction:: mitogen.main
mitogen.core
------------
.. automodule:: mitogen.core
.. currentmodule:: mitogen.core
.. autodecorator:: takes_econtext
.. currentmodule:: mitogen.core
.. autodecorator:: takes_router
mitogen.master
--------------
.. automodule:: mitogen.master
mitogen.parent
--------------
.. automodule:: mitogen.parent
mitogen.fakessh
---------------
.. image:: images/fakessh.svg
:class: mitogen-right-300
.. automodule:: mitogen.fakessh
.. currentmodule:: mitogen.fakessh
.. autofunction:: run (dest, router, args, daedline=None, econtext=None)
Message Class
=============
.. currentmodule:: mitogen.core
.. autoclass:: Message
:members:
Router Class
============
.. currentmodule:: mitogen.core
.. autoclass:: Router
:members:
.. currentmodule:: mitogen.parent
.. autoclass:: Router
:members:
.. currentmodule:: mitogen.master
.. autoclass:: Router (broker=None)
:members:
.. _context-factories:
Connection Methods
==================
.. currentmodule:: mitogen.parent
.. method:: Router.fork (on_fork=None, on_start=None, debug=False, profiling=False, via=None)
Construct a context on the local machine by forking the current
process. The forked child receives a new identity, sets up a new broker
and router, and responds to function calls identically to children
created using other methods.
The use of this method is strongly discouraged. It requires Python 2.6 or
newer, as older Pythons made no effort to reset threading state upon fork.
For long-lived processes, :meth:`local` is always better as it
guarantees a pristine interpreter state that inherited little from the
parent. Forking should only be used in performance-sensitive scenarios
where short-lived children must be spawned to isolate potentially buggy
code, and only after accounting for all the bad things possible as a
result of, at a minimum:
* Files open in the parent remaining open in the child,
causing the lifetime of the underlying object to be extended
indefinitely.
* From the perspective of external components, this is observable
in the form of pipes and sockets that are never closed, which may
break anything relying on closure to signal protocol termination.
* Descriptors that reference temporary files will not have their disk
space reclaimed until the child exits.
* Third party package state, such as urllib3's HTTP connection pool,
attempting to write to file descriptors shared with the parent,
causing random failures in both parent and child.
* UNIX signal handlers installed in the parent process remaining active
in the child, despite associated resources, such as service threads,
child processes, resource usage counters or process timers becoming
absent or reset in the child.
* Library code that makes assumptions about the process ID remaining
unchanged, for example to implement inter-process locking, or to
generate file names.
* Anonymous ``MAP_PRIVATE`` memory mappings whose storage requirement
doubles as either parent or child dirties their pages.
* File-backed memory mappings that cannot have their space freed on
disk due to the mapping living on in the child.
* Difficult to diagnose memory usage and latency spikes due to object
graphs becoming unreferenced in either parent or child, causing
immediate copy-on-write to large portions of the process heap.
* Locks held in the parent causing random deadlocks in the child, such
as when another thread emits a log entry via the :mod:`logging`
package concurrent to another thread calling :meth:`fork`, or when a C
extension module calls the C library allocator, or when a thread is using
the C library DNS resolver, for example via :func:`socket.gethostbyname`.
* Objects existing in Thread-Local Storage of every non-:meth:`fork`
thread becoming permanently inaccessible, and never having their
object destructors called, including TLS usage by native extension
code, triggering many new variants of all the issues above.
* Pseudo-Random Number Generator state that is easily observable by
network peers to be duplicate, violating requirements of
cryptographic protocols through one-time state reuse. In the worst
case, children continually reuse the same state due to repeatedly
forking from a static parent.
:meth:`fork` cleans up Mitogen-internal objects, in addition to
locks held by the :mod:`logging` package, reseeds
:func:`random.random`, and the OpenSSL PRNG via
:func:`ssl.RAND_add`, but only if the :mod:`ssl` module is
already loaded. You must arrange for your program's state, including
any third party packages in use, to be cleaned up by specifying an
`on_fork` function.
The associated stream implementation is
:class:`mitogen.fork.Stream`.
:param function on_fork:
Function invoked as `on_fork()` from within the child process. This
permits supplying a program-specific cleanup function to break
locks and close file descriptors belonging to the parent from
within the child.
:param function on_start:
Invoked as `on_start(econtext)` from within the child process after
it has been set up, but before the function dispatch loop starts.
This permits supplying a custom child main function that inherits
rich data structures that cannot normally be passed via a
serialization.
:param mitogen.core.Context via:
Same as the `via` parameter for :meth:`local`.
:param bool debug:
Same as the `debug` parameter for :meth:`local`.
:param bool profiling:
Same as the `profiling` parameter for :meth:`local`.
.. method:: Router.local (remote_name=None, python_path=None, debug=False, connect_timeout=None, profiling=False, via=None)
Construct a context on the local machine as a subprocess of the current
process. The associated stream implementation is
:class:`mitogen.master.Stream`.
:param str remote_name:
The ``argv[0]`` suffix for the new process. If `remote_name` is
``test``, the new process ``argv[0]`` will be ``mitogen:test``.
If unspecified, defaults to ``<username>@<hostname>:<pid>``.
This variable cannot contain slash characters, as the resulting
``argv[0]`` must be presented in such a way as to allow Python to
determine its installation prefix. This is required to support
virtualenv.
:param str|list python_path:
String or list path to the Python interpreter to use for bootstrap.
Defaults to :data:`sys.executable` for local connections, and
``python`` for remote connections.
It is possible to pass a list to invoke Python wrapped using
another tool, such as ``["/usr/bin/env", "python"]``.
:param bool debug:
If :data:`True`, arrange for debug logging (:meth:`enable_debug`) to
be enabled in the new context. Automatically :data:`True` when
:meth:`enable_debug` has been called, but may be used
selectively otherwise.
:param bool unidirectional:
If :data:`True`, arrange for the child's router to be constructed
with :attr:`unidirectional routing
<mitogen.core.Router.unidirectional>` enabled. Automatically
:data:`True` when it was enabled for this router, but may still be
explicitly set to :data:`False`.
:param float connect_timeout:
Fractional seconds to wait for the subprocess to indicate it is
healthy. Defaults to 30 seconds.
:param bool profiling:
If :data:`True`, arrange for profiling (:data:`profiling`) to be
enabled in the new context. Automatically :data:`True` when
:data:`profiling` is :data:`True`, but may be used selectively
otherwise.
:param mitogen.core.Context via:
If not :data:`None`, arrange for construction to occur via RPCs
made to the context `via`, and for :data:`ADD_ROUTE
<mitogen.core.ADD_ROUTE>` messages to be generated as appropriate.
.. code-block:: python
# SSH to the remote machine.
remote_machine = router.ssh(hostname='mybox.com')
# Use the SSH connection to create a sudo connection.
remote_root = router.sudo(username='root', via=remote_machine)
.. method:: Router.doas (username=None, password=None, doas_path=None, password_prompt=None, incorrect_prompts=None, \**kwargs)
Construct a context on the local machine over a ``doas`` invocation.
The ``doas`` process is started in a newly allocated pseudo-terminal,
and supports typing interactive passwords.
Accepts all parameters accepted by :meth:`local`, in addition to:
:param str username:
Username to use, defaults to ``root``.
:param str password:
The account password to use if requested.
:param str doas_path:
Filename or complete path to the ``doas`` binary. ``PATH`` will be
searched if given as a filename. Defaults to ``doas``.
:param bytes password_prompt:
A string that indicates ``doas`` is requesting a password. Defaults
to ``Password:``.
:param list incorrect_prompts:
List of bytestrings indicating the password is incorrect. Defaults
to `(b"doas: authentication failed")`.
:raises mitogen.doas.PasswordError:
A password was requested but none was provided, the supplied
password was incorrect, or the target account did not exist.
.. method:: Router.docker (container=None, image=None, docker_path=None, \**kwargs)
Construct a context on the local machine within an existing or
temporary new Docker container using the ``docker`` program. One of
`container` or `image` must be specified.
Accepts all parameters accepted by :meth:`local`, in addition to:
:param str container:
Existing container to connect to. Defaults to :data:`None`.
:param str username:
Username within the container to :func:`setuid` to. Defaults to
:data:`None`, which Docker interprets as ``root``.
:param str image:
Image tag to use to construct a temporary container. Defaults to
:data:`None`.
:param str docker_path:
Filename or complete path to the Docker binary. ``PATH`` will be
searched if given as a filename. Defaults to ``docker``.
.. method:: Router.jail (container, jexec_path=None, \**kwargs)
Construct a context on the local machine within a FreeBSD jail using
the ``jexec`` program.
Accepts all parameters accepted by :meth:`local`, in addition to:
:param str container:
Existing container to connect to. Defaults to :data:`None`.
:param str username:
Username within the container to :func:`setuid` to. Defaults to
:data:`None`, which ``jexec`` interprets as ``root``.
:param str jexec_path:
Filename or complete path to the ``jexec`` binary. ``PATH`` will be
searched if given as a filename. Defaults to ``/usr/sbin/jexec``.
.. method:: Router.kubectl (pod, kubectl_path=None, kubectl_args=None, \**kwargs)
Construct a context in a container via the Kubernetes ``kubectl``
program.
Accepts all parameters accepted by :meth:`local`, in addition to:
:param str pod:
Kubernetes pod to connect to.
:param str kubectl_path:
Filename or complete path to the ``kubectl`` binary. ``PATH`` will
be searched if given as a filename. Defaults to ``kubectl``.
:param list kubectl_args:
Additional arguments to pass to the ``kubectl`` command.
.. method:: Router.lxc (container, lxc_attach_path=None, \**kwargs)
Construct a context on the local machine within an LXC classic
container using the ``lxc-attach`` program.
Accepts all parameters accepted by :meth:`local`, in addition to:
:param str container:
Existing container to connect to. Defaults to :data:`None`.
:param str lxc_attach_path:
Filename or complete path to the ``lxc-attach`` binary. ``PATH``
will be searched if given as a filename. Defaults to
``lxc-attach``.
.. method:: Router.lxd (container, lxc_path=None, \**kwargs)
Construct a context on the local machine within a LXD container using
the ``lxc`` program.
Accepts all parameters accepted by :meth:`local`, in addition to:
:param str container:
Existing container to connect to. Defaults to :data:`None`.
:param str lxc_path:
Filename or complete path to the ``lxc`` binary. ``PATH`` will be
searched if given as a filename. Defaults to ``lxc``.
.. method:: Router.setns (container, kind, username=None, docker_path=None, lxc_info_path=None, machinectl_path=None, \**kwargs)
Construct a context in the style of :meth:`local`, but change the
active Linux process namespaces via calls to `setns(2)` before
executing Python.
The namespaces to use, and the active root file system are taken from
the root PID of a running Docker, LXC, LXD, or systemd-nspawn
container.
The setns method depends on the built-in :mod:`ctypes` module, and thus
does not support Python 2.4.
A program is required only to find the root PID, after which management
of the child Python interpreter is handled directly.
:param str container:
Container to connect to.
:param str kind:
One of ``docker``, ``lxc``, ``lxd`` or ``machinectl``.
:param str username:
Username within the container to :func:`setuid` to. Defaults to
``root``.
:param str docker_path:
Filename or complete path to the Docker binary. ``PATH`` will be
searched if given as a filename. Defaults to ``docker``.
:param str lxc_path:
Filename or complete path to the LXD ``lxc`` binary. ``PATH`` will
be searched if given as a filename. Defaults to ``lxc``.
:param str lxc_info_path:
Filename or complete path to the LXC ``lxc-info`` binary. ``PATH``
will be searched if given as a filename. Defaults to ``lxc-info``.
:param str machinectl_path:
Filename or complete path to the ``machinectl`` binary. ``PATH``
will be searched if given as a filename. Defaults to
``machinectl``.
.. method:: Router.su (username=None, password=None, su_path=None, password_prompt=None, incorrect_prompts=None, \**kwargs)
Construct a context on the local machine over a ``su`` invocation. The
``su`` process is started in a newly allocated pseudo-terminal, and
supports typing interactive passwords.
Accepts all parameters accepted by :meth:`local`, in addition to:
:param str username:
Username to pass to ``su``, defaults to ``root``.
:param str password:
The account password to use if requested.
:param str su_path:
Filename or complete path to the ``su`` binary. ``PATH`` will be
searched if given as a filename. Defaults to ``su``.
:param bytes password_prompt:
The string that indicates ``su`` is requesting a password. Defaults
to ``Password:``.
:param str incorrect_prompts:
Strings that signal the password is incorrect. Defaults to `("su:
sorry", "su: authentication failure")`.
:raises mitogen.su.PasswordError:
A password was requested but none was provided, the supplied
password was incorrect, or (on BSD) the target account did not
exist.
.. method:: Router.sudo (username=None, sudo_path=None, password=None, \**kwargs)
Construct a context on the local machine over a ``sudo`` invocation.
The ``sudo`` process is started in a newly allocated pseudo-terminal,
and supports typing interactive passwords.
Accepts all parameters accepted by :meth:`local`, in addition to:
:param str username:
Username to pass to sudo as the ``-u`` parameter, defaults to
``root``.
:param str sudo_path:
Filename or complete path to the sudo binary. ``PATH`` will be
searched if given as a filename. Defaults to ``sudo``.
:param str password:
The password to use if/when sudo requests it. Depending on the sudo
configuration, this is either the current account password or the
target account password. :class:`mitogen.sudo.PasswordError`
will be raised if sudo requests a password but none is provided.
:param bool set_home:
If :data:`True`, request ``sudo`` set the ``HOME`` environment
variable to match the target UNIX account.
:param bool preserve_env:
If :data:`True`, request ``sudo`` to preserve the environment of
the parent process.
:param str selinux_type:
If not :data:`None`, the SELinux security context to use.
:param str selinux_role:
If not :data:`None`, the SELinux role to use.
:param list sudo_args:
Arguments in the style of :data:`sys.argv` that would normally
be passed to ``sudo``. The arguments are parsed in-process to set
equivalent parameters. Re-parsing ensures unsupported options cause
:class:`mitogen.core.StreamError` to be raised, and that
attributes of the stream match the actual behaviour of ``sudo``.
.. method:: Router.ssh (hostname, username=None, ssh_path=None, ssh_args=None, port=None, check_host_keys='enforce', password=None, identity_file=None, identities_only=True, compression=True, \**kwargs)
Construct a remote context over an OpenSSH ``ssh`` invocation.
The ``ssh`` process is started in a newly allocated pseudo-terminal to
support typing interactive passwords and responding to prompts, if a
password is specified, or `check_host_keys=accept`. In other scenarios,
``BatchMode`` is enabled and no PTY is allocated. For many-target
configurations, both options should be avoided as most systems have a
conservative limit on the number of pseudo-terminals that may exist.
Accepts all parameters accepted by :meth:`local`, in addition to:
:param str username:
The SSH username; default is unspecified, which causes SSH to pick
the username to use.
:param str ssh_path:
Absolute or relative path to ``ssh``. Defaults to ``ssh``.
:param list ssh_args:
Additional arguments to pass to the SSH command.
:param int port:
Port number to connect to; default is unspecified, which causes SSH
to pick the port number.
:param str check_host_keys:
Specifies the SSH host key checking mode. Defaults to ``enforce``.
* ``ignore``: no host key checking is performed. Connections never
fail due to an unknown or changed host key.
* ``accept``: known hosts keys are checked to ensure they match,
new host keys are automatically accepted and verified in future
connections.
* ``enforce``: known host keys are checked to ensure they match,
unknown hosts cause a connection failure.
:param str password:
Password to type if/when ``ssh`` requests it. If not specified and
a password is requested, :class:`mitogen.ssh.PasswordError` is
raised.
:param str identity_file:
Path to an SSH private key file to use for authentication. Default
is unspecified, which causes SSH to pick the identity file.
When this option is specified, only `identity_file` will be used by
the SSH client to perform authenticaion; agent authentication is
automatically disabled, as is reading the default private key from
``~/.ssh/id_rsa``, or ``~/.ssh/id_dsa``.
:param bool identities_only:
If :data:`True` and a password or explicit identity file is
specified, instruct the SSH client to disable any authentication
identities inherited from the surrounding environment, such as
those loaded in any running ``ssh-agent``, or default key files
present in ``~/.ssh``. This ensures authentication attempts only
occur using the supplied password or SSH key.
:param bool compression:
If :data:`True`, enable ``ssh`` compression support. Compression
has a minimal effect on the size of modules transmitted, as they
are already compressed, however it has a large effect on every
remaining message in the otherwise uncompressed stream protocol,
such as function call arguments and return values.
:param int ssh_debug_level:
Optional integer `0..3` indicating the SSH client debug level.
:raises mitogen.ssh.PasswordError:
A password was requested but none was specified, or the specified
password was incorrect.
:raises mitogen.ssh.HostKeyError:
When `check_host_keys` is set to either ``accept``, indicates a
previously recorded key no longer matches the remote machine. When
set to ``enforce``, as above, but additionally indicates no
previously recorded key exists for the remote machine.
Context Class
=============
.. currentmodule:: mitogen.core
.. autoclass:: Context
:members:
.. currentmodule:: mitogen.parent
.. autoclass:: Context
:members:
.. currentmodule:: mitogen.parent
.. autoclass:: CallChain
:members:
Receiver Class
==============
.. currentmodule:: mitogen.core
.. autoclass:: Receiver
:members:
Sender Class
============
.. currentmodule:: mitogen.core
.. autoclass:: Sender
:members:
Select Class
============
.. module:: mitogen.select
.. currentmodule:: mitogen.select
.. autoclass:: Event
:members:
.. autoclass:: Select
:members:
Channel Class
=============
.. currentmodule:: mitogen.core
.. autoclass:: Channel
:members:
Broker Class
============
.. currentmodule:: mitogen.core
.. autoclass:: Broker
:members:
.. currentmodule:: mitogen.master
.. autoclass:: Broker
:members:
Fork Safety
===========
.. currentmodule:: mitogen.os_fork
.. autoclass:: Corker
:members:
Utility Functions
=================
.. currentmodule:: mitogen.core
.. function:: now
A reference to :func:`time.time` on Python 2, or :func:`time.monotonic` on
Python >3.3. We prefer :func:`time.monotonic` when available to ensure
timers are not impacted by system clock changes.
.. module:: mitogen.utils
A random assortment of utility functions useful on masters and children.
.. currentmodule:: mitogen.utils
.. autofunction:: cast
.. currentmodule:: mitogen.utils
.. autofunction:: setup_gil
.. autofunction:: disable_site_packages
.. autofunction:: log_to_file
.. autofunction:: run_with_router(func, \*args, \**kwargs)
.. currentmodule:: mitogen.utils
.. decorator:: with_router
Decorator version of :func:`run_with_router`. Example:
.. code-block:: python
@with_router
def do_stuff(router, arg):
pass
do_stuff(blah, 123)
Exceptions
==========
.. currentmodule:: mitogen.core
.. autoclass:: Error
.. autoclass:: CallError
.. autoclass:: ChannelError
.. autoclass:: LatchError
.. autoclass:: StreamError
.. autoclass:: TimeoutError
.. currentmodule:: mitogen.parent
.. autoclass:: EofError
.. autoclass:: CancelledError
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