[BUG] /health endpoint on mlflow model serve

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Willingness to contribute

The MLflow Community encourages bug fix contributions. Would you or another member of your organization be willing to contribute a fix for this bug to the MLflow code base?

• Yes. I can contribute a fix for this bug independently.
• Yes. I would be willing to contribute a fix for this bug with guidance from the MLflow community.
• No. I cannot contribute a bug fix at this time.

System information

• Have I written custom code (as opposed to using a stock example script provided in MLflow): no
• OS Platform and Distribution (e.g., Linux Ubuntu 16.04): python:3.7 official image
• MLflow installed from (source or binary):
• MLflow version (run mlflow --version): 1.20.2
• Python version: python:3.7 official image
• npm version, if running the dev UI:
• Exact command to reproduce: mlflow models serve

Describe the problem

Describe the problem clearly here. Include descriptions of the expected behavior and the actual behavior. The feature request here: https://github.com/mlflow/mlflow/pull/2725 does not appear to affect mlflow model serve servers.
Expected that server launched by mlflow model serve would answer to /health calls, specifically responding with a 200 OK

Code to reproduce issue

Provide a reproducible test case that is the bare minimum necessary to generate the problem. mlflow model serve
curl <model_url>/health

Other info / logs

Include any logs or source code that would be helpful to diagnose the problem. If including tracebacks, please include the full traceback. Large logs and files should be attached. [2021-10-13 02:33:35 +0000] [51] [DEBUG] GET /health -- ip -- "GET /health HTTP/1.1" 404 232 5207 "curl/7.54.0" -

What component(s), interfaces, languages, and integrations does this bug 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

Interface

• 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

Language

• 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

[gabriel-milan]

For now though, I think we should support /health as an alternative path to the /ping endpoint. Would you be able to make a PR for that? If not, no worries - I can put one up as well

Hello there! I’ve faced this issue a while ago and decided to open a PR myself (https://github.com/mlflow/mlflow/pull/6574). I hope this is fine.

[ankit-db]

Btw, re: that v2 protocol, we are merging https://github.com/mlflow/mlflow/pull/4845 soon which will add the MLServer to the MLflow project, and I think if you’re looking for a fully formed server for use in K8s, it probably makes sense to use that.

For now though, I think we should support /health as an alternative path to the /ping endpoint. Would you be able to make a PR for that? If not, no worries - I can put one up as well