# Creating A Coordinator

The principal object provided by tooz is the coordinator. It allows you to use various features, such as group membership, leader election or distributed locking.

The features provided by tooz coordinator are implemented using different drivers. When creating a coordinator, you need to specify which back-end driver you want it to use. Different drivers may provide different set of capabilities.

If a driver does not support a feature, it will raise a `NotImplemented` exception.

This example program loads a basic coordinator using the ZooKeeper based driver.

    # Copyright (C) 2020 Red Hat, Inc.
    #
    # Licensed under the Apache License, Version 2.0 (the "License");
    # you may not use this file except in compliance with the License.
    # You may obtain a copy of the License at
    #
    #    http://www.apache.org/licenses/LICENSE-2.0
    #
    # Unless required by applicable law or agreed to in writing, software
    # distributed under the License is distributed on an "AS IS" BASIS,
    # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
    # implied.
    # See the License for the specific language governing permissions and
    # limitations under the License.

    from tooz import coordination

    coordinator = coordination.get_coordinator('zake://', b'host-1')
    coordinator.start()
    coordinator.stop()

The second argument passed to the coordinator must be a unique identifier identifying the running program.

After the coordinator is created, it can be used to use the various features provided.

In order to keep the connection to the coordination server active, the method `heartbeat()` method must be called regularly. This will ensure that the coordinator is not considered dead by other program participating in the coordination. Unless you want to call it manually, you can use tooz builtin heartbeat manager by passing the start_heart argument.

    # Copyright (C) 2020 Red Hat, Inc.
    #
    # Licensed under the Apache License, Version 2.0 (the "License");
    # you may not use this file except in compliance with the License.
    # You may obtain a copy of the License at
    #
    #    http://www.apache.org/licenses/LICENSE-2.0
    #
    # Unless required by applicable law or agreed to in writing, software
    # distributed under the License is distributed on an "AS IS" BASIS,
    # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
    # implied.
    # See the License for the specific language governing permissions and
    # limitations under the License.

    from tooz import coordination

    coordinator = coordination.get_coordinator('zake://', b'host-1')
    coordinator.start(start_heart=True)
    coordinator.stop()

heartbeat at different moment or intervals.

Note that certain drivers, such as memcached are heavily based on timeout, so the interval used to run the heartbeat is important.

this page last updated: 2025-02-03 10:42:00

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