many-migrations 1.1

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Many: A library to migrate anything!

Managing state changes in data stores is an important part of the development process. There are many great migration tool available for SQL-like databases. However, there is lack of support for other data stores. Because of that I created a small library called many which can be used to build your own migration tool for any data store.

Creating your own application

To create your own migration application for your data store:

1. Subclass the MigrationEngine class and implement its methods.
2. Optionally, create a customized migration template by using Mako templates.
3. Initialize your application using init_app function with your customized MigrationEngine and Template
4. Run you application.

How this would look like:

# migration_app.py

from many import MigrationEngine, init_app

class CustomEngine(MigrationEngine):
    def init_remote(self):
        # Add logic to initialize a place where the state can be maintained (e.g. a table).

    def remote_exists(self) -> bool:
        # Add logic to check whether the remote state exists.

    def update_remote(self, state: str):
        # Add logic to update the remote state to the provided state

    def get_remote(self) -> str:
        # Add logic to get the remote state 

    def prepare_args(self) -> Tuple[Any]:
        # Logic to pass any argument to the actual migration (e.g. a session/connection object).
        
if __name__ == "__main__":
    app = init_app(CustomEngine())
    app()

Now, this application can be used as follows:

1. python migration_app.py revision create -m "My first migration" to create your first revision in the versions folder.
2. Modify the generated file in the versions to customize your migration.
3. python migration_app.py migrate up to upgrade the state to the latest migration.
4. python migration_app.py migrate down to downgrade the state one level. Use python migration_app.py migrate down --level base to downgrade completely.

Examples

I have added some examples to showcase how to use the library by implementing some migration applications for:

• Elasticsearch: examples/elasticsearch
• Apache Iceberg: examples/iceberg
• PostgreSQL: examples/postgresql