Tutum Schedule

A minimalistic image to handle scheduling processes as Tutum Services

Introduction

I had a number of ETL-like jobs and background processes that needed to run on varying schedules. I was running each process in its own Docker container and using cron to start the process when it was required. However, this method was error-prone. Running cron in a Docker container requires careful configuration and can create problems that are be difficult to debug. Further, the longer you run a container, the more issues you face regarding inconsistent environments, exactly the issue you're trying to avoid by using Docker.

As a response, I created this Tutum Schedule Dockerfile and utility functions to help manage scheduling Docker containers. To use it, set up your own configuration in tutum-schedule.py. Deploy it as its own Service on Tutum and stop worrying about your background processes.

Usage

Tutum Schedule relies on the awesome Python schedule package created by dbader. It implements a simple, Pythonic interface to schedule tasks.

Examples from the docs:

def job():
    print("I'm working...")

schedule.every().day.at("10:30").do(job)
schedule.every().monday.do(job)

In tutum-schedule.py.sample, I've provided a sample script to deploy with for your own jobs. In addition to a few example schedule jobs, I've also provided two helper functions:

• start_service(uuid): used for restarting stopped services that are saved in your Tutum account;
• create_service(**kwargs): used for creating a new service in your Tutum account. create_service() takes any of the parameters listed in the Tutum API documentation for creating a service.

Notes:

• The schedule package runs jobs serially. This shouldn't be a problem here, as the time to make a Tutum API call is pretty minimal. However, if you put a longer-running function in your job, it could cause issues.
• Be sure you're using the correct function out of start_service and create_service. For start_service, the target Service should already be created and save (but not Running!) in your Tutum account. For create_service, the target Service should exist yet, and you will need to pass all the necessary parameters for your Service to be created properly. This includes environment variables, container links, and run command.

Deploy

To deploy this to Tutum, create your own tutum-schedule.py with your desired configuration. Once you're ready, run:

docker build -t tutum.co/<username>/<image_name> .
docker push tutum.co/<username>/<image_name>

Go to your Tutum account and deploy the Service. Be sure to assign the global role to the Service so it can use the Tutum API on your behalf.