monarch 0.0.4

The un-migration migration tool

HEY WATCHOUT THIS IS IN NO WAY GURANTEED TO WORK.

[Documentation Work in Progress]

“migrations should happen naturally”

monarch is a migration CLI (command line interface) to help manage developers with migrations.

What makes monarch unique is what it does not supply:

• monarch does not provide a DSL or DDL for database specific migrations (like South and alembic)

• monarch does not care which database you use, mongo, postres – it does matter to us

The main use-case that was the inspiration of this tool is adding a migration to a feature using CI

When we develop a feature we implement the following:

• the feature

• tests

• necessary migrations that move the production data to where it needs to be to rock the new feature

So now with monarch we can implement a Pull Request(PR) with the feature, test and migration. And once your Continuous Integration says that your tests are cool then you can deploy and run the pending migrations needed for your feature.

Install

pip install monarch

Usage

0. Configure

In your application working directory run:

monarch init

This will create a migration/settings.py file for you. Open it up and configure it to your needs.

1. Generate a Migration

monarch create add_indexes_to_user_table

That will create a template migration that looks something like this

# in ./migrations/_201405290038_add_indexes_to_user_table_migration.py

from monarch import MongoBackedMigration

class AddIndexesToUserTableMigration(MongoBackedMigration):

    def run(self):
        """Write the code here that will migrate the database from one state to the next
        No Need to handle exceptions -- we will take care of that for you
        """
        raise NotImplementedError

2. Implement the Migration

Do whatever you want in that run method. I mean anything! Go crazy wild man.

3. When the time is right, run the pending migrations:

monarch migrate

Configuration

By default it will look in ./migrations/settings.py.

It should look something like this:

# migrations/settings.py
MONGO_SETTINGS = {
    DB_NAME = 'test_monarch'
    DB_PORT = 27017
}

You can run monarch init to setup the initial file

Road Map

• Be able to test migrations monarch test