[FR] Stabilize the custom app plugin interface

[jmahlik]

Willingness to contribute

Yes. I can contribute this feature independently.

Proposal Summary

Passing --app-name is marked as experimental in the docs. It's been around for some releases now and the interface works well. The built in authentication feature also relies on this interface to implement the authenticated app.

I have been running a custom app in prod without issue. This FR is to stabilize the api and remove the experimental flag. Mostly so users can feel comfortable deploying a custom app without the worry that one day it will be removed or changed substantially.

I would also submit a PR to add a more realistic plugin example based on my findings implementing one in the wild.

• https://github.com/mlflow/mlflow/blob/v2.8.0/tests/resources/mlflow-test-plugin/mlflow_test_plugin/app.py
• https://github.com/mlflow/mlflow/blob/v2.8.0/mlflow/server/__init__.py#L144-L152

Let me know thoughts.

Motivation

What is the use case for this feature?

Deploying a custom app.

Why is this use case valuable to support for MLflow users in general?

It's highly valuable to customize the app in some cases, like custom json logging and authentication hooks.

Why is this use case valuable to support for your project(s) or organization?

Already using the feature, would just like to stabilize it.

Why is it currently difficult to achieve this use case?

n/a

Details

No response

What component(s) does this bug affect?

• area/artifacts: Artifact stores and artifact logging
• area/build: Build and test infrastructure for MLflow
• area/docs: MLflow documentation pages
• area/examples: Example code
• area/gateway: AI Gateway service, Gateway client APIs, third-party Gateway integrations
• area/model-registry: Model Registry service, APIs, and the fluent client calls for Model Registry
• area/models: MLmodel format, model serialization/deserialization, flavors
• area/recipes: Recipes, Recipe APIs, Recipe configs, Recipe Templates
• area/projects: MLproject format, project running backends
• area/scoring: MLflow Model server, model deployment tools, Spark UDFs
• area/server-infra: MLflow Tracking server backend
• area/tracking: Tracking Service, tracking client APIs, autologging

What interface(s) does this bug affect?

• area/uiux: Front-end, user experience, plotting, JavaScript, JavaScript dev server
• area/docker: Docker use across MLflow's components, such as MLflow Projects and MLflow Models
• area/sqlalchemy: Use of SQLAlchemy in the Tracking Service or Model Registry
• area/windows: Windows support

What language(s) does this bug affect?

• language/r: R APIs and clients
• language/java: Java APIs and clients
• language/new: Proposals for new client languages

What integration(s) does this bug affect?

• integrations/azure: Azure and Azure ML integrations
• integrations/sagemaker: SageMaker integrations
• integrations/databricks: Databricks integrations

[BenWilson2]

@jmahlik both ideas are great. We'll look forward to the PRs :)
Please tag me in the example PR - we'll want to fit the presentation and formatting in with our docs overhaul and make your new example into an official guide on its own page (as well as create a new landing page for customizing MLflow through plugins - your new guide will be the first added one to this new section of the docs site)

[github-actions]

@mlflow/mlflow-team Please assign a maintainer and start triaging this issue.