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jobslib

Jobslib is a library for launching Python tasks in parallel environment. Our use-case is. We have two datacenters (in near future three datacenters), in each datacenter is run server with some task. However only one task may be active at one time across all datacenters. Jobslib solves this problem.

Main features are:

  • Ancestor for class which holds configuration.
  • Ancestor for container for shared resources, e.g. database connection.
  • Ancestor for class with task.
  • Configurable either from configuration file or from environmet variables.
  • Liveness – mechanism for exporting informations about health state of the task. Jobslib includes implementation which uses Consul.
  • Metrics – mechanism for exporting metrics. Jobslib includes implementation which uses InfluxDB.
  • One Instance Lock – lock, which allowes only one running instance at the same time. Jobslib includes implementation which uses Consul.

Installation

Installation from source code:

$ git clone https://github.com/seznam/jobslib.git
$ cd jobslib
$ python setup.py install

Installation from PyPi:

$ pip install jobslib

Tox is used for testing:

$ git clone https://github.com/seznam/jobslib.git
$ cd jobslib
$ pip install tox
$ tox --skip-missing-interpreters

Usage

Task is launched from command line using runjob command:

$ runjob [-s SETTINGS] [--disable-one-instance] [--run-once]
         [--sleep-interval SLEEP_INTERVAL] [--run-interval RUN_INTERVAL]
         [--keep-lock] [--release-on-error]
         task_cls

# Pass settings module using -s argument
$ runjob -s myapp.settings myapp.task.HelloWorldTask --run-once

# Pass settings module using environment variable
$ export JOBSLIB_SETTINGS_MODULE="myapp.settings"
$ runjob myapp.task.HelloWorldTask --run-once

If you want to write your own task, inherit BaseTask class and override BaseTask.task() method. According to your requirements inherit and override Config and/or Context and set settings module.

class HelloWorldTask(BaseTask):

    name = 'helloworld'
    description = 'prints hello world'

    def task(self):
        sys.stdout.write('Hello World!\n')
        sys.stdout.flush()

License

3-clause BSD

Documentation

https://seznam.github.io/jobslib/