Introduction

The ox_herd_example package illustrates how to get a very simple application setup using ox_herd for job scheduling. Although you can do many things with ox_herd, a simple way to think of it is a pythonic replacement for the UNIX cron package.

That is, you can write simple python tasks and schedule them to run at set intervals. The advantages of doing this with ox_herd include:

1. Using python instead of cron and shell scripts.
2. A nice flask web interface to your tasks.
3. Ability to include that web interface as a flask blueprint in other flask projects.
4. Ability to use the web interface to configure your cron schedule.
5. Ability to use the web interface to see task results.

Demo Via Docker

In this section, we describe how to use docker to do a simple demo of how ox_herd can function as a pythonic cron.

To run this example, do the following:

1. git clone https://github.com/emin63/ox_herd_example
   • This will download the git repo from github.
2. cd ox_herd_example
3. docker-compose up --build
   • This will build and start the docker image.
4. Point your browser to http://127.0.0.1:5000/login
   • Note that on windows, docker networking works differently and you will have to do docker-machine ip and use that IP address instead of 127.0.0.1.
5. Login with user test_user and enter the password printed in the terminal where you started docker.
   • The app.py should print a random password to the screen so that only you can see it to keep things secure.
6. After you succesfully login, go to http://127.0.0.1:5000/ox_herd/show_plugins to see the plugins which are loaded.
   • Notice the example_plugins which is loaded by the app.py file.
7. Click on example_plugins to expand it and the click on CheckWeb.
   • This will take you to a form to configure the plugin.
8. Set the name field to test_cw and the queue_name to default and hit the Go button.
   • You have now configured this plugin to run on the given cron schedule on the default python rq worker queue.
9. If you now go to the Show_Scheduled link at http://127.0.0.1:5000/ox_herd/show_plugins, you should see your plugin has been schedule.
10. Click on your scheduled test_cw job and click Launch Job Copy.
    • This shows how you can force launching of a copy of the job outside of the regular cron schedule.
11. Next, click the List Tasks link at http://127.0.0.1:5000/ox_herd/list_tasks and you should see an entry for your task.

Concluding Remarks

This example illustrates a very simple demo of how you can use ox_herd as a job scheduler. Our docker example sets up a new machine, installs ox_herd, and creates a simple flask app in ox_herd_example/app.py to use the ox_herd blueprint.

Next steps:

1. As one next step, you could further customize the module used in ox_herd_example/example_plugins.py to provide more plugins so you have more jobs to schedule.
2. As another next step you could build a bigger flask application using ox_herd to do things like download financial data, monitor your web site, do automated testing, etc.