Databricks Model Serving

Deploy MLflow models and AI agents to scalable REST API endpoints.

Quick Decision: What Are You Deploying?

Model Type Pattern Reference

Traditional ML (sklearn, xgboost) mlflow.sklearn.autolog()

1-classical-ml.md

Custom Python model mlflow.pyfunc.PythonModel

2-custom-pyfunc.md

GenAI Agent (LangGraph, tool-calling) ResponsesAgent

3-genai-agents.md

Prerequisites

• DBR 16.1+ recommended (pre-installed GenAI packages)

• Unity Catalog enabled workspace

• Model Serving enabled

Reference Files

Topic File When to Read

Classical ML 1-classical-ml.md sklearn, xgboost, autolog

Custom PyFunc 2-custom-pyfunc.md Custom preprocessing, signatures

GenAI Agents 3-genai-agents.md ResponsesAgent, LangGraph

Tools Integration 4-tools-integration.md UC Functions, Vector Search

Development & Testing 5-development-testing.md MCP workflow, iteration

Logging & Registration 6-logging-registration.md mlflow.pyfunc.log_model

Deployment 7-deployment.md Job-based async deployment

Querying Endpoints 8-querying-endpoints.md SDK, REST, MCP tools

Package Requirements 9-package-requirements.md DBR versions, pip

Quick Start: Deploy a GenAI Agent

Step 1: Install Packages (in notebook or via MCP)

%pip install -U mlflow==3.6.0 databricks-langchain langgraph==0.3.4 databricks-agents pydantic dbutils.library.restartPython()

Or via MCP:

execute_databricks_command(code="%pip install -U mlflow==3.6.0 databricks-langchain langgraph==0.3.4 databricks-agents pydantic")

Step 2: Create Agent File

Create agent.py locally with ResponsesAgent pattern (see 3-genai-agents.md).

Step 3: Upload to Workspace

upload_folder( local_folder="./my_agent", workspace_folder="/Workspace/Users/you@company.com/my_agent" )

Step 4: Test Agent

run_python_file_on_databricks( file_path="./my_agent/test_agent.py", cluster_id="<cluster_id>" )

Step 5: Log Model

run_python_file_on_databricks( file_path="./my_agent/log_model.py", cluster_id="<cluster_id>" )

Step 6: Deploy (Async via Job)

See 7-deployment.md for job-based deployment that doesn't timeout.

Step 7: Query Endpoint

query_serving_endpoint( name="my-agent-endpoint", messages=[{"role": "user", "content": "Hello!"}] )

Quick Start: Deploy a Classical ML Model

import mlflow import mlflow.sklearn from sklearn.linear_model import LogisticRegression

Enable autolog with auto-registration

mlflow.sklearn.autolog( log_input_examples=True, registered_model_name="main.models.my_classifier" )

Train - model is logged and registered automatically

model = LogisticRegression() model.fit(X_train, y_train)

Then deploy via UI or SDK. See 1-classical-ml.md.

MCP Tools

If MCP tools are not available, use the SDK/CLI examples in the reference files below.

Development & Testing

Tool Purpose

upload_folder

Upload agent files to workspace

run_python_file_on_databricks

Test agent, log model

execute_databricks_command

Install packages, quick tests

Deployment

Tool Purpose

create_job

Create deployment job (one-time)

run_job_now

Kick off deployment (async)

get_run

Check deployment job status

Querying

Tool Purpose

get_serving_endpoint_status

Check if endpoint is READY

query_serving_endpoint

Send requests to endpoint

list_serving_endpoints

List all endpoints

Common Workflows

Check Endpoint Status After Deployment

get_serving_endpoint_status(name="my-agent-endpoint")

Returns:

{ "name": "my-agent-endpoint", "state": "READY", "served_entities": [...] }

Query a Chat/Agent Endpoint

query_serving_endpoint( name="my-agent-endpoint", messages=[ {"role": "user", "content": "What is Databricks?"} ], max_tokens=500 )

Query a Traditional ML Endpoint

query_serving_endpoint( name="sklearn-classifier", dataframe_records=[ {"age": 25, "income": 50000, "credit_score": 720} ] )

Common Issues

Issue Solution

Invalid output format Use self.create_text_output_item(text, id)

• NOT raw dicts!

Endpoint NOT_READY Deployment takes ~15 min. Use get_serving_endpoint_status to poll.

Package not found Specify exact versions in pip_requirements when logging model

Tool timeout Use job-based deployment, not synchronous calls

Auth error on endpoint Ensure resources specified in log_model for auto passthrough

Model not found Check Unity Catalog path: catalog.schema.model_name

Critical: ResponsesAgent Output Format

WRONG - raw dicts don't work:

return ResponsesAgentResponse(output=[{"role": "assistant", "content": "..."}])

CORRECT - use helper methods:

return ResponsesAgentResponse( output=[self.create_text_output_item(text="...", id="msg_1")] )

Available helper methods:

• self.create_text_output_item(text, id)

• text responses

• self.create_function_call_item(id, call_id, name, arguments)

• tool calls

• self.create_function_call_output_item(call_id, output)

• tool results

Resources

• Model Serving Documentation

• MLflow 3 ResponsesAgent

• Agent Framework