[FR] [Roadmap] Generate Open API / swagger for MLflow APIs

MLflow Roadmap Item

This is an MLflow Roadmap item that has been prioritized by the MLflow maintainers. We’ve identified this feature as a highly requested addition to the MLflow package based on community feedback. We’re seeking a community contribution for the implementation of this feature and will enthusiastically support the development and review of a submitted PR for this.

Contribution Note

As with other roadmap items, there may be a desire for multiple contributors to work on an issue. While we don’t discourage collaboration, we strongly encourage that a primary contributor is assigned to roadmap issues to simplify the merging process. The items on the roadmap are of a high priority. Due to the wide-spread demand of roadmap features, we encourage potential contributors to only agree to take on the work of creating a PR, making changes, and ensuring that test coverage is adequately created for the feature if they are willing and able to see the implementation through to a merged state.

Feature scope

This roadmap feature’s complexity is classified as:

• good-first-issue: This feature is limited in complexity and effort required to implement.
• simple: This feature does not require a large amount of effort to implement and / or is clear enough to not need a design discussion with maintainers.
• involved: This feature will require a substantial amount of development effort but does not require an agreed-upon design from the maintainers. The feedback given during the PR phase may be involved and necessitate multiple iterations before approval. (Please bear with us as we collaborate with you to make a great contribution)
• design-recommended: This is a substantial feature that should have a design document approved prior to working on an implementation (to save your time, not ours). After agreeing to work on this feature, a maintainer will be assigned to support you throughout the development process.

Proposal Summary

Generate Swagger definitions from the grpc protobuf definitions to map to OpenAPI standards. A recommended approach for generating these files is to look into the gnostic library.

The original FR for this: #2948

Motivation

What is the use case for this feature?

Allow for stub creation through swagger codegen for interfacing with Mlflow APIs and (outside of scope for this FR) support swagger ui eventually.

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

Aids in developer experience and reduces the time and complexity to create interface APIs to MLflow REST endpoints.

What component(s), interfaces, languages, and integrations does this feature affect?

Components

• 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/model-registry: Model Registry service, APIs, and the fluent client calls for Model Registry
• area/models: MLmodel format, model serialization/deserialization, flavors
• 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

Interfaces

• 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

Languages

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

Integrations

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

[rafaelvp-db]

@BenWilson2 I’m willing to take this one. Maybe slightly off-topic: would it make sense to also include replacing Flask with FastAPI in the roadmap (Swagger docs would come out of the box and it’s more performant than Flask). Let me know what you think!

[nfx]

@marrrcin Ah I get what you mean now. OpenAPI for /invocations is a separate issue, not that much related to this one. We need to create a separate issue to track that one