monitoring – Tools for monitoring driver events.

Tools to monitor driver events.

New in version 3.1.

Use register() to register global listeners for specific events. Listeners must inherit from one of the abstract classes below and implement the correct functions for that class.

For example, a simple command logger might be implemented like this:

import logging

from pymongo import monitoring

class CommandLogger(monitoring.CommandListener):

    def started(self, event):
        logging.info("Command {0.command_name} with request id "
                     "{0.request_id} started on server "
                     "{0.connection_id}".format(event))

    def succeeded(self, event):
        logging.info("Command {0.command_name} with request id "
                     "{0.request_id} on server {0.connection_id} "
                     "succeeded in {0.duration_micros} "
                     "microseconds".format(event))

    def failed(self, event):
        logging.info("Command {0.command_name} with request id "
                     "{0.request_id} on server {0.connection_id} "
                     "failed in {0.duration_micros} "
                     "microseconds".format(event))

monitoring.register(CommandLogger())

Server discovery and monitoring events are also available. For example:

class ServerLogger(monitoring.ServerListener):

    def opened(self, event):
        logging.info("Server {0.server_address} added to topology "
                     "{0.topology_id}".format(event))

    def description_changed(self, event):
        previous_server_type = event.previous_description.server_type
        new_server_type = event.new_description.server_type
        if new_server_type != previous_server_type:
            # server_type_name was added in PyMongo 3.4
            logging.info(
                "Server {0.server_address} changed type from "
                "{0.previous_description.server_type_name} to "
                "{0.new_description.server_type_name}".format(event))

    def closed(self, event):
        logging.warning("Server {0.server_address} removed from topology "
                        "{0.topology_id}".format(event))


class HeartbeatLogger(monitoring.ServerHeartbeatListener):

    def started(self, event):
        logging.info("Heartbeat sent to server "
                     "{0.connection_id}".format(event))

    def succeeded(self, event):
        # The reply.document attribute was added in PyMongo 3.4.
        logging.info("Heartbeat to server {0.connection_id} "
                     "succeeded with reply "
                     "{0.reply.document}".format(event))

    def failed(self, event):
        logging.warning("Heartbeat to server {0.connection_id} "
                        "failed with error {0.reply}".format(event))

class TopologyLogger(monitoring.TopologyListener):

    def opened(self, event):
        logging.info("Topology with id {0.topology_id} "
                     "opened".format(event))

    def description_changed(self, event):
        logging.info("Topology description updated for "
                     "topology id {0.topology_id}".format(event))
        previous_topology_type = event.previous_description.topology_type
        new_topology_type = event.new_description.topology_type
        if new_topology_type != previous_topology_type:
            # topology_type_name was added in PyMongo 3.4
            logging.info(
                "Topology {0.topology_id} changed type from "
                "{0.previous_description.topology_type_name} to "
                "{0.new_description.topology_type_name}".format(event))
        # The has_writable_server and has_readable_server methods
        # were added in PyMongo 3.4.
        if not event.new_description.has_writable_server():
            logging.warning("No writable servers available.")
        if not event.new_description.has_readable_server():
            logging.warning("No readable servers available.")

    def closed(self, event):
        logging.info("Topology with id {0.topology_id} "
                     "closed".format(event))

Event listeners can also be registered per instance of MongoClient:

client = MongoClient(event_listeners=[CommandLogger()])

Note that previously registered global listeners are automatically included when configuring per client event listeners. Registering a new global listener will not add that listener to existing client instances.

Note

Events are delivered synchronously. Application threads block waiting for event handlers (e.g. started()) to return. Care must be taken to ensure that your event handlers are efficient enough to not adversely affect overall application performance.

Warning

The command documents published through this API are not copies. If you intend to modify them in any way you must copy them in your event handler first.

pymongo.monitoring.register(listener)

Register a global event listener.

Parameters:

• listener: A subclasses of CommandListener, ServerHeartbeatListener, ServerListener, or TopologyListener.

class pymongo.monitoring.CommandListener

Abstract base class for command listeners. Handles CommandStartedEvent, CommandSucceededEvent, and CommandFailedEvent.

failed(event)

Abstract method to handle a CommandFailedEvent.

Parameters:

• event: An instance of CommandFailedEvent.

started(event)

Abstract method to handle a CommandStartedEvent.

Parameters:

• event: An instance of CommandStartedEvent.

succeeded(event)

Abstract method to handle a CommandSucceededEvent.

Parameters:

• event: An instance of CommandSucceededEvent.

class pymongo.monitoring.ServerListener

Abstract base class for server listeners. Handles ServerOpeningEvent, ServerDescriptionChangedEvent, and ServerClosedEvent.

New in version 3.3.

closed(event)

Abstract method to handle a ServerClosedEvent.

Parameters:

• event: An instance of ServerClosedEvent.

description_changed(event)

Abstract method to handle a ServerDescriptionChangedEvent.

Parameters:

• event: An instance of ServerDescriptionChangedEvent.

opened(event)

Abstract method to handle a ServerOpeningEvent.

Parameters:

• event: An instance of ServerOpeningEvent.

class pymongo.monitoring.ServerHeartbeatListener

Abstract base class for server heartbeat listeners. Handles ServerHeartbeatStartedEvent, ServerHeartbeatSucceededEvent, and ServerHeartbeatFailedEvent.

New in version 3.3.

failed(event)

Abstract method to handle a ServerHeartbeatFailedEvent.

Parameters:

• event: An instance of ServerHeartbeatFailedEvent.

started(event)

Abstract method to handle a ServerHeartbeatStartedEvent.

Parameters:

• event: An instance of ServerHeartbeatStartedEvent.

succeeded(event)

Abstract method to handle a ServerHeartbeatSucceededEvent.

Parameters:

• event: An instance of ServerHeartbeatSucceededEvent.

class pymongo.monitoring.TopologyListener

Abstract base class for topology monitoring listeners. Handles TopologyOpenedEvent, TopologyDescriptionChangedEvent, and TopologyClosedEvent.

New in version 3.3.

closed(event)

Abstract method to handle a TopologyClosedEvent.

Parameters:

• event: An instance of TopologyClosedEvent.

description_changed(event)

Abstract method to handle a TopologyDescriptionChangedEvent.

Parameters:

• event: An instance of TopologyDescriptionChangedEvent.

opened(event)

Abstract method to handle a TopologyOpenedEvent.

Parameters:

• event: An instance of TopologyOpenedEvent.

class pymongo.monitoring.CommandStartedEvent(command, database_name, *args)

Event published when a command starts.

Parameters:

• command: The command document.
• database_name: The name of the database this command was run against.
• request_id: The request id for this operation.
• connection_id: The address (host, port) of the server this command was sent to.
• operation_id: An optional identifier for a series of related events.

command

The command document.

command_name

The command name.

connection_id

The address (host, port) of the server this command was sent to.

database_name

The name of the database this command was run against.

operation_id

An id for this series of events or None.

request_id

The request id for this operation.

class pymongo.monitoring.CommandSucceededEvent(duration, reply, command_name, request_id, connection_id, operation_id)

Event published when a command succeeds.

Parameters:

• duration: The command duration as a datetime.timedelta.
• reply: The server reply document.
• command_name: The command name.
• request_id: The request id for this operation.
• connection_id: The address (host, port) of the server this command was sent to.
• operation_id: An optional identifier for a series of related events.

command_name

The command name.

connection_id

The address (host, port) of the server this command was sent to.

duration_micros

The duration of this operation in microseconds.

operation_id

An id for this series of events or None.

reply

The server failure document for this operation.

request_id

The request id for this operation.

class pymongo.monitoring.CommandFailedEvent(duration, failure, *args)

Event published when a command fails.

Parameters:

• duration: The command duration as a datetime.timedelta.
• failure: The server reply document.
• command_name: The command name.
• request_id: The request id for this operation.
• connection_id: The address (host, port) of the server this command was sent to.
• operation_id: An optional identifier for a series of related events.

command_name

The command name.

connection_id

The address (host, port) of the server this command was sent to.

duration_micros

The duration of this operation in microseconds.

failure

The server failure document for this operation.

operation_id

An id for this series of events or None.

request_id

The request id for this operation.

class pymongo.monitoring.ServerDescriptionChangedEvent(previous_description, new_description, *args)

Published when server description changes.

New in version 3.3.

new_description

The new ServerDescription.

previous_description

The previous ServerDescription.

server_address

The address (host/port pair) of the server

topology_id

A unique identifier for the topology this server is a part of.

class pymongo.monitoring.ServerOpeningEvent(server_address, topology_id)

Published when server is initialized.

New in version 3.3.

server_address

The address (host/port pair) of the server

topology_id

A unique identifier for the topology this server is a part of.

class pymongo.monitoring.ServerClosedEvent(server_address, topology_id)

Published when server is closed.

New in version 3.3.

server_address

The address (host/port pair) of the server

topology_id

A unique identifier for the topology this server is a part of.

class pymongo.monitoring.TopologyDescriptionChangedEvent(previous_description, new_description, *args)

Published when the topology description changes.

New in version 3.3.

new_description

The new TopologyDescription.

previous_description

The previous TopologyDescription.

topology_id

A unique identifier for the topology this server is a part of.

class pymongo.monitoring.TopologyOpenedEvent(topology_id)

Published when the topology is initialized.

New in version 3.3.

topology_id

A unique identifier for the topology this server is a part of.

class pymongo.monitoring.TopologyClosedEvent(topology_id)

Published when the topology is closed.

New in version 3.3.

topology_id

A unique identifier for the topology this server is a part of.

class pymongo.monitoring.ServerHeartbeatStartedEvent(connection_id)

Published when a heartbeat is started.

New in version 3.3.

connection_id

The address (host, port) of the server this heartbeat was sent to.

class pymongo.monitoring.ServerHeartbeatSucceededEvent(duration, reply, *args)

Fired when the server heartbeat succeeds.

New in version 3.3.

connection_id

The address (host, port) of the server this heartbeat was sent to.

duration

The duration of this heartbeat in microseconds.

reply

An instance of IsMaster.

class pymongo.monitoring.ServerHeartbeatFailedEvent(duration, reply, *args)

Fired when the server heartbeat fails, either with an “ok: 0” or a socket exception.

New in version 3.3.

connection_id

The address (host, port) of the server this heartbeat was sent to.

duration

The duration of this heartbeat in microseconds.

reply

A subclass of Exception.