Task Scheduling

Introduction

Often your application will require some kind of recurring task that should happen at a specific time of the week, every minute, or every few months. These tasks can be things like:

• Reading XML from a directory and importing it into a remote database

• Checking if a customer is still a subscriber in Stripe and updating your local database

• Cleaning your database of unneeded data every minute or so

• Send an API call to a service in order to fire certain events

Or anything in between. There are lots of use cases for simple tasks to be ran during certain parts of the day or even "offline" hours when your employees are gone.

Getting Started

Installation

First we will need to install the scheduler feature. We can simply pip install it:

terminal

$ pip install masonite-scheduler

Masonite will fetch all tasks from the container by finding all subclasses of scheduler.tasks.Task, check if they should run and then either execute it or not execute it.

Adding the Service Provider

Next we will need to add the service provider. We can do that by importing it into our config/providers.py file like this:

from scheduler.providers import ScheduleProvider
...
PROVIDERS = [
    AppProvider
    ...
    # Third Part Providers
    ScheduleProvider,
    # Application Providers
    
]

Now if you run craft you will see 2 new commands you can use.

Commands

You will now see a craft task command and a craft schedule:run which we will use below to demonstrate how to create and run tasks.

Creating a Task

We can create a task by running

$ craft task SayHi

This should create a task like the example below. So let's change the task a bit by printing "Hi" and setting it to run every minute:

from scheduler.Task import Task


class SayHi(Task):

    run_every = '1 minute'

    def __init__(self):
        pass

    def handle(self):
        print('Hi!')

Binding to the container automatically

In order for Masonite to find the tasks, they need to be inside the container.

Masonite also has a great feature called autoloading. Although the above way of binding directly to the container manually works it may be more easy to automatically load your tasks.

You can do this by adding this to your AUTOLOAD variable in config/application.py:

AUTOLOAD = [
    'app',
    'app/tasks',
]

Binding to the container manually

Of course you can also bind each task manually as well.

If you already have a provider in your application then go ahead and bind to that one but we'll walk through how to create a new provider for all of our tasks:

$ craft provider TasksProvider

We can now bind our task into the provider like so:

...
from app.tasks.SayHi import SayHi

class TasksProvider(ServiceProvider):

    wsgi = False
    
    def register(self):
        """Register objects into the Service Container
        """
        
        self.app.bind('SayHiTask', SayHi)

And then just make sure you add this container to the PROVIDERS list too:

from scheduler.providers import ScheduleProvider
from app.providers.TasksProvider import TasksProvider
...
PROVIDERS = [
    AppProvider
    ...
    # Third Part Providers
    ScheduleProvider,
    # Application Providers
    TasksProvider,
]

Running the scheduler

Now let's run the schedule:run command:

$ craft schedule:run

We should now see "Hi!" output to the terminal window.

Running a Specific Task

You may also run a specific task by running the schedule:run command with a --task flag. The flag value is the container binding (usually the task class name):

 craft schedule:run --task SayHi

Or you can give your task a name explicitly:

from scheduler.Task import Task


class SayHi(Task):

    run_every = '1 minute'
    name = 'hey'

    def __init__(self):
        pass

    def handle(self):
        print('Hi!')

and then run the command by name

 craft schedule:run --task hey

Cron Jobs

Setting up Cron Jobs are for UNIX based machines like Mac and Linux only. Windows has a similar schedule called Task Scheduler which is similar but will require different instructions in setting it up.

Although the command above is useful, it is not very practical in a production setup. In production, we should setup a cron job to run that command every minute so Masonite can decide on what jobs need to be ran.

We'll show you an example cron job and then we will walk through how to build it.

PATH=/Users/Masonite/Programming/project_name/venv/bin:/Library/Frameworks/Python.framework/Versions/3.6/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Library/Frameworks/Python.framework/Versions/3.6/bin
* * * * * cd /Users/Masonite/Programming/project_name && source venv/bin/activate && craft schedule:run

Getting The Path

When a cron job runs, it will typically run commands with a /bin/sh command instead of the usual /bin/bash. Because of this, craft may not be found on the machine so we need to tell the cron job the PATH that should be loaded in. We can simply find the PATH by going to our project directory and running:

$ env

Which will show an output of something like:

...
__CF_USER_TEXT_ENCODING=0x1F5:0x0:0x0
PATH=/Library/Frameworks/Python.framework/Versions/3.6/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Library/Frameworks/Python.framework/Versions/3.6/bin
PWD=/Users/Masonite/Programming/masonite
...

If you are using a virtual environment for development purposes then you need to run the env command inside your virtual environment.

We can then copy the PATH and put it in the cron job.

To enter into cron, just run:

$ env EDITOR=nano crontab -e

and paste the PATH we just copied. Once we do that our cron should look like:

PATH=/Users/Masonite/Programming/masonitetesting/venv/bin:/Library/Frameworks/Python.framework/Versions/3.6/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Library/Frameworks/Python.framework/Versions/3.6/bin

Exit out of nano. Now we just need to setup the actual cron job:

Setting The Cron Task

Now we just need to setup the cron task itself. This could be as easy as copying it and pasting it into the nano editor again. You may need to change a few things though.

The first * * * * * part is a must and bascially means "run this every minute by default". The next part is the location of your application which is dependant on where you installed your Masonite application.

The next part is dependant on your setup. If you have a virtual environment then you need to activate it by appending && source venv/bin/activate to the cron task. If you are not running in a virtual environment then you can leave that part out.

Lastly we need to run the schedule command so we can append && craft schedule:run

Great! Now we have a cron job that will run the craft command every minute. Masonite will decide which classes need to be executed.