Django Post Deploy

This module adds a way automate release-specific post-deploy/post-migrate actions to your Django project.

Features

• Allow actions to be scheduled with the deployment automation
  • But also give the oppurtunity to keep special actions out of the automation and have those executed manually.
• Schedule the actions to be executed in Celery.
  • The task scheduler is configurable, so you can write your own.
• Support for django_tenants.

Alternatives

Alternative to this module you can use:

• Management tasks. Used once and in the future confuse developers "Must we also maintain this code?"
• "Empty" migrations. That
  • may or may not activate all custom expected code for it...
  • may or may not depend on other migrations being completed.

Why use this module?

This module is of use for your application if you:

• want to keep management commands clean of one-time-used code.
• want to have release finishing tasks executed in a certain and known state of the application.

Example

# Inside a custom django module's post_deploy.py
from post_deploy import post_deploy_action


@post_deploy_action
def make_non_code_changes_to_complete_the_next_release():
    pass


@post_deploy_action(auto=False)
def this_action_must_be_triggered_manually():
    pass

# This line may be added to your deployment automation script
python manage.py deploy --auto

# This line is executed when the time is right for specific actions
$ ./manage.py deploy --one core.post_deploy.this_action_must_be_triggered_manually

# Or like this: both auto and manual actions are scheduled:
$ ./manage.py deploy --all

# Print actions that are running, have errors and are completed.
$ ./manage.py deploy --status

# Print actions that completed with errors, or did not run yet. The tasks with errors may need
# to be scheduled with the --once option.
$ ./manage.py deploy --todo

# Print uuids of the tasks that have run before; for debugging purposes.
$ ./manage.py deploy --uuids

# This is an example of running a custom action
$ ./manage.py deploy --one core.a_custom_repository_of_functions.a_custom_function_to_be_executed

# This is an example of running an action only if it has not started before, or when it completed with errors
$ ./manage.py deploy --once core.post_deploy.failed_before_or_did_not_run_yet

# In this example a non-processed task will be marked complete
$ ./manage.py deploy --skip core.post_deploy.aint_no_run_no_more

# In this example a processed task will become ready to schedule (again)
$ ./manage.py deploy --reset core.post_deploy.run_again_at_all_or_auto

Configuration

The module is to be installed as an app in the django settings.

# inside your projects settings.py file:

INSTALLED_APPS = [
    ...,
    'post_deploy',
]

Celery

Out of the box the deploy management command runs the actions serially. However, if you use Celery you have to add this to your settings:

# inside your projects settings.py file:

POST_DEPLOY_CELERY_APP = 'module.path.to.your.projects.celery.app'
POST_DEPLOY_SCHEDULER_MANAGER = 'post_deploy.plugins.scheduler.celery.CeleryScheduler'

Custom scheduler manager

Below is a partial copy of othe Celery scheduler manager as an example on how to write one for your alternative task scheduler:

NOTICE: remember to configure your custom scheduler manager in your project settings.

from celery import Celery
from celery.result import AsyncResult

from post_deploy.plugins.scheduler import DefaultScheduler


class CeleryScheduler(DefaultScheduler):
    ...

    def task_ready(self, id):
        return AsyncResult(id=id, app=...).ready()

    def schedule(self, action_ids, context_kwargs):
        from post_deploy.tasks import deploy_task
        result = deploy_task.delay(action_ids, context_kwargs)
        return result.id

    ...

Django tenants

This module supports the django_tenants module. In order to make the post deploy actions tenant aware two things are different from normal operation. You have to (1) configure a context manager, and (2) the management command is a little different.

BE AWARE!!! Make sure that you install the post_deploy app in the SHARED_APPS section. Not doing this may lead to unexpected results.

# inside your projects settings.py file, two additions:

SHARED_APPS = [
    ...,
    'post_deploy',
]

TENANT_APPS = [
    ...,
    'post_deploy',
]

...

POST_DEPLOY_CONTEXT_MANAGER = 'post_deploy.plugins.context.tenant.TenantContext'

# The tenant schema is transported to the celery task runner when the management
# command is executed in the given schema aware management commands. For example:

# all_tenants_command example:
$ ./manage.py all_tenants_command deploy --all

# tenant_command example:
$ ./manage.py tenant_command deploy --report --schema=public

Example on how to have actions behave different based on the selected schema:

# Inside a module's post_deploy.py
from django_tenants.utils import parse_tenant_config_path
from post_deploy import post_deploy_action


@post_deploy_action
def example_on_how_alter_operation_based_on_schema():
    if parse_tenant_config_path("") == 'public':
        # Do 'public' specific operations.
        pass

    # else, proceed as required.
    ...

License information

django_post_deploy (c) by Erlend ter Maat

django_post_deploy is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

You should have received a copy of the license along with this work. If not, see http://creativecommons.org/licenses/by-sa/4.0/.