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Register workflows

The orchestrator needs to know which workflows are available for which products. This is a two stage registration process. The workflows need to be registered as a workflow function in the code and a mapping between workflow and product_type needs to be added to the database through migration script. First we will add the workflow functions. For creating the migration script, we can either let the cli create an empty one and fill it manually or use the db migrate-workflows command to generate one based on the diffs between the registered workflows in the code and the database.

Step 1: Map workflow function to package

Registering workflow functions in the code is done by creating appropriate LazyWorkflowInstance instances that maps a workflow function to the Python package where it is defined.

For example, the LazyWorkflowInstance for the UserGroup create workflow looks like this:

from orchestrator.workflows import LazyWorkflowInstance

LazyWorkflowInstance("workflows.user_group.create_user_group", "create_user_group")

Add the LazyWorkflowInstance calls for all six workflows to workflows/__init__. py, and add import workflows to so the instances are created as part of the workflow package.


for inspiration look at an example implementation of the lazy workflow instances

Step 2: Register workflow in database

There are several ways to complete this step:

Copy the example workflows migration

  cd migrations/versions/schema
  curl --remote-name

And restart the Docker compose environment.

Migrate workflows generator script

Similar to db migrate-domain-models, the orchestrator command line interface offers the db migrate-workflows command that walks you through a menu to create a database migration file based on the difference between the registered workflows in the code and the database.

Start with the following command:

python db migrate-workflows "add User and UserGroup workflows"

Navigate through the menu to add the six workflows to the corresponding User or UserGroup product type. After confirming a migration file will be added to migrations/versions/schema The migration can be run with:

python db upgrade heads


Create a new empty database migration with the following command:

PYTHONPATH=. python db revision --head data --message "add User and UserGroup workflows"

This will create an empty database migration in the folder migrations/versions/schema. For the migration we will make use of the migration helper functions create_workflow and delete_workflow that both expect a Dict that describes the workflow registration to be added or deleted from the database.

To add all User and UserGroup workflows in bulk a list of Dict is created, for only the UserGroup create workflow the list looks like this:

from orchestrator.targets import Target

new_workflows = [
        "name": "create_user_group",
        "target": Target.CREATE,
        "description": "Create user group",
        "product_type": "UserGroup",

This registers the workflow function create_user_group as a create workflow for the UserGroup product.

Add a list of Dicts describing the create, modify and terminate workflows for both the UserGroup and User products to the migration that was created above.

The migration upgrade and downgrade functions will just loop through the list:

from orchestrator.migrations.helpers import create_workflow, delete_workflow

def upgrade() -> None:
    conn = op.get_bind()
    for workflow in new_workflows:
        create_workflow(conn, workflow)

def downgrade() -> None:
    conn = op.get_bind()
    for workflow in new_workflows:
        delete_workflow(conn, workflow["name"])

Run the migration with the following command:

PYTHONPATH=. python db upgrade heads