MLflow Authentication

Experimental Feature

This feature is still experimental and may be enhanced in a future release without warning.

MLflow Authentication provides secure access control for experiments and registered models through HTTP basic authentication. Once enabled, users must authenticate before accessing any resources on the Tracking Server.

Quick Start

Installation & Setup

Install MLflow with authentication dependencies:

pip install mlflow[auth]

Set your server secret key and start the authenticated server:

export MLFLOW_FLASK_SERVER_SECRET_KEY="my-secret-key"
mlflow server --app-name basic-auth

Important

The secret key must be consistent across multiple servers to prevent validation errors.

Default Admin Access

MLflow creates a default admin user on first startup:

Username	Password
admin	password1234

Security Recommendation

Update the default admin password immediately after first login using the /api/2.0/mlflow/users/update-password endpoint.

Core Concepts

Permission Levels

MLflow uses a hierarchical permission system with four levels:

Permission	Read	Update	Delete	Manage
READ	✅	❌	❌	❌
EDIT	✅	✅	❌	❌
MANAGE	✅	✅	✅	✅
NO_PERMISSIONS	❌	❌	❌	❌

The default permission for all users is READ, configurable in the auth configuration file.

Resource Types

Permissions are granted on two main resource types:

• Experiments - Controls access to experiment data and runs
• Registered Models - Controls access to model registry operations

Authentication Methods

Interactive Login (Recommended)

Use mlflow.login() for a guided authentication setup:

import mlflow

# Interactive login with prompts
mlflow.login()

# Login to Databricks (currently the only supported backend)
mlflow.login(backend="databricks", interactive=True)

# Non-interactive mode (requires existing credentials)
mlflow.login(backend="databricks", interactive=False)

# After login, start using MLflow normally
with mlflow.start_run():
    mlflow.log_metric("accuracy", 0.95)

Interactive Experience

mlflow.login() will prompt you for credentials if none are found and automatically save them for future use. For Databricks, it saves to ~/.databrickscfg.

Environment Variables

Set authentication credentials in your environment:

export MLFLOW_TRACKING_USERNAME=your_username
export MLFLOW_TRACKING_PASSWORD=your_password

import mlflow

mlflow.set_tracking_uri("https://your-mlflow-server.com")
with mlflow.start_run():
    # Your authenticated MLflow operations
    mlflow.log_metric("accuracy", 0.95)

Credentials File

Store credentials in ~/.mlflow/credentials (protected by filesystem permissions):

[mlflow]
mlflow_tracking_username = your_username
mlflow_tracking_password = your_password

Credential Priority

Environment variables take precedence over credentials file. This allows for easy overrides in different environments.

Advanced Authentication Options

MLflow supports additional authentication methods and security configurations:

Token-based Authentication

import os

os.environ["MLFLOW_TRACKING_TOKEN"] = "your_api_token"

AWS SigV4 Authentication

import os

os.environ["MLFLOW_TRACKING_AWS_SIGV4"] = "true"

Custom Authentication Headers

import os

os.environ["MLFLOW_TRACKING_AUTH"] = "custom_auth_header_value"

TLS/SSL Configuration

import os

# Disable TLS verification (not recommended for production)
os.environ["MLFLOW_TRACKING_INSECURE_TLS"] = "true"

# Custom client certificate
os.environ["MLFLOW_TRACKING_CLIENT_CERT_PATH"] = "/path/to/client.crt"

# Custom server certificate
os.environ["MLFLOW_TRACKING_SERVER_CERT_PATH"] = "/path/to/server.crt"

Security Note

Only disable TLS verification in development environments. Always use proper certificates in production.

User Management

Creating Users

Using the Web Interface

Navigate to <tracking_uri>/signup to access the user creation form.

Using the Python Client

from mlflow.server import get_app_client

# Authenticate as admin
auth_client = get_app_client("basic-auth", tracking_uri="https://your-server.com")
user = auth_client.create_user(username="newuser", password="secure_password")

print(f"Created user: {user.username} (ID: {user.id})")

Using REST API

import requests

response = requests.post(
    "https://your-server.com/api/2.0/mlflow/users/create",
    json={"username": "newuser", "password": "secure_password"},
    auth=("admin", "password1234"),
)

Managing Admin Status

Only existing admins can promote users to admin status:

# Promote user to admin
auth_client.update_user_admin(username="newuser", is_admin=True)

# Remove admin privileges
auth_client.update_user_admin(username="newuser", is_admin=False)

Permission Management

Experiment Permissions

Grant users specific permissions on experiments:

from mlflow import MlflowClient

# Create experiment and grant permissions
client = MlflowClient(tracking_uri="https://your-server.com")
experiment_id = client.create_experiment("my_experiment")

# Grant MANAGE permission to user
auth_client.create_experiment_permission(
    experiment_id=experiment_id, username="data_scientist", permission="MANAGE"
)

# Update existing permission
auth_client.update_experiment_permission(
    experiment_id=experiment_id, username="data_scientist", permission="EDIT"
)

# Check current permission
permission = auth_client.get_experiment_permission(
    experiment_id=experiment_id, username="data_scientist"
)
print(f"User permission: {permission.permission}")

Registered Model Permissions

Control access to model registry operations:

# Create model with automatic MANAGE permission for creator
model = client.create_registered_model("my_model")

# Grant READ permission to another user
auth_client.create_registered_model_permission(
    name="my_model", username="ml_engineer", permission="READ"
)

# Update to EDIT permission
auth_client.update_registered_model_permission(
    name="my_model", username="ml_engineer", permission="EDIT"
)

API Reference

Core Endpoints

User Management

Endpoint	Method	Description	Required Permission
/api/2.0/mlflow/users/create	POST	Create new user	Admin only
/api/2.0/mlflow/users/get	GET	Get user info	Self only
/api/2.0/mlflow/users/update-password	PATCH	Update password	Self only
/api/2.0/mlflow/users/update-admin	PATCH	Update admin status	Admin only
/api/2.0/mlflow/users/delete	DELETE	Delete user	Admin only

Experiment Permissions

Endpoint	Method	Required Permission
/api/2.0/mlflow/experiments/permissions/create	POST	can_manage
/api/2.0/mlflow/experiments/permissions/get	GET	can_manage
/api/2.0/mlflow/experiments/permissions/update	PATCH	can_manage
/api/2.0/mlflow/experiments/permissions/delete	DELETE	can_manage

Model Registry Permissions

Endpoint	Method	Required Permission
/api/2.0/mlflow/registered-models/permissions/create	POST	can_manage
/api/2.0/mlflow/registered-models/permissions/get	GET	can_manage
/api/2.0/mlflow/registered-models/permissions/update	PATCH	can_manage
/api/2.0/mlflow/registered-models/permissions/delete	DELETE	can_manage

Enhanced Behavior

When authentication is enabled, certain APIs automatically filter results based on user permissions:

• Search Experiments - Returns only experiments the user can read
• Search Runs - Returns only runs from readable experiments
• Search Registered Models - Returns only models the user can read
• Create Operations - Automatically grants MANAGE permission to creators

Configuration

Database Configuration

MLflow uses SQLite by default, but supports centralized databases for multi-node deployments:

# /path/to/auth_config.ini
[mlflow]
database_uri = postgresql://username:password@hostname:port/database
default_permission = READ
admin_username = admin
admin_password = password1234
authorization_function = mlflow.server.auth:authenticate_request_basic_auth

Start the server with custom configuration:

MLFLOW_AUTH_CONFIG_PATH=/path/to/auth_config.ini mlflow server --app-name basic-auth

Database Migration

Run database migrations when needed:

python -m mlflow.server.auth db upgrade --url <database_url>

Advanced Topics

Custom Authentication

MLflow supports custom authentication methods through pluggable functions:

# custom_auth.py
from werkzeug.datastructures import Authorization
from flask import Response


def custom_authenticate() -> Union[Authorization, Response]:
    # Your custom authentication logic
    # Return Authorization object if authenticated
    # Return Response object (401) if not authenticated
    pass

Update configuration to use your custom function:

[mlflow]
authorization_function = custom_auth:custom_authenticate

Plugin Development

Create installable authentication plugins:

# my_auth_plugin/__init__.py
from flask import Flask
from mlflow.server import app


def create_app(my_app: Flask = app):
    # Extend MLflow app with custom auth logic
    my_app.add_url_rule(...)
    return my_app


class MyAuthClient:
    # Custom client for managing permissions
    pass

Register your plugin:

# setup.py
setup(
    entry_points={
        "mlflow.app": ["my-auth=my_auth_plugin:create_app"],
        "mlflow.app.client": ["my-auth=my_auth_plugin:MyAuthClient"],
    }
)

Security Best Practices

Password Security

• Use strong passwords (minimum 12 characters)
• Rotate credentials regularly
• Store credentials securely using environment variables or secure credential files

Network Security

• Use HTTPS in production environments
• Configure proper firewall rules
• Consider using reverse proxy with additional security headers

Database Security

• Use encrypted connections to your database
• Regularly backup authentication data
• Implement proper database access controls

Monitoring

• Monitor authentication logs for suspicious activity
• Set up alerts for failed authentication attempts
• Regularly audit user permissions

Troubleshooting

Common Issues

Secret Key Errors

Solution: Ensure MLFLOW_FLASK_SERVER_SECRET_KEY is set and consistent across all servers

Permission Denied (403)

Solution: Check user permissions using get_experiment_permission or get_registered_model_permission

Authentication Failed (401)

Solution: Verify username/password and ensure user exists in the system

Database Connection Issues

Solution: Verify database_uri in configuration and ensure database is accessible

Debugging Tips

1. Enable Debug Logging

   export MLFLOW_LOGGING_LEVEL=DEBUG

2. Check User Permissions

   # Verify current user permissions
   user = auth_client.get_user("username")
   print(f"Is admin: {user.is_admin}")
   
   permission = auth_client.get_experiment_permission("exp_id", "username")
   print(f"Experiment permission: {permission.permission}")

3. Database Inspection

   # Check database tables
   sqlite3 basic_auth.db ".tables"
   sqlite3 basic_auth.db "SELECT * FROM users;"

Migration Guide

Enabling Authentication on Existing Server

1. Backup your data before enabling authentication
2. Install auth dependencies: pip install mlflow[auth]
3. Set secret key: export MLFLOW_FLASK_SERVER_SECRET_KEY="your-key"
4. Restart server: mlflow server --app-name basic-auth
5. Update admin password immediately after first login

Disabling Authentication

To disable authentication, simply restart the server without the --app-name basic-auth flag. User data and permissions will be preserved for future re-enabling.

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Need Help? Check the MLflow Authentication API Reference for detailed function documentation.