MLflow Authentication

Note

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

MLflow supports basic HTTP authentication to enable access control over experiments and registered models. Once enabled, any visitor will be required to login before they can view any resource from the Tracking Server.

MLflow Authentication provides Python and REST API for managing users and permissions.

• MLflow Authentication Python API
• MLflow Authentication REST API

Overview

To enable MLflow authentication, launch the MLflow UI with the following command:

mlflow server --app-name basic-auth

Server admin can choose to disable this feature anytime by restarting the server without the app-name flag. Any users and permissions created will be persisted on a SQL database and will be back in service once the feature is re-enabled.

Due to the nature of HTTP authentication, it is only supported on a remote Tracking Server, where users send requests to the server via REST APIs.

How It Works

Permissions

The available permissions are:

Permission	Can read	Can update	Can delete	Can manage
READ	Yes	No	No	No
EDIT	Yes	Yes	No	No
MANAGE	Yes	Yes	Yes	Yes
NO_PERMISSIONS	No	No	No	No

The default permission for all users is READ. It can be changed in the configuration file.

Permissions can be granted on individual resources for each user. Supported resources include Experiment and Registered Model. To access an API endpoint, an user must have the required permission. Otherwise, a 403 Forbidden response will be returned.

Required Permissions for accessing experiments:

API	Endpoint	Method	Required permission
Create Experiment	2.0/mlflow/experiments/create	POST	None
Get Experiment	2.0/mlflow/experiments/get	GET	can_read
Get Experiment By Name	2.0/mlflow/experiments/get-by-name	GET	can_read
Delete Experiment	2.0/mlflow/experiments/delete	POST	can_delete
Restore Experiment	2.0/mlflow/experiments/restore	POST	can_delete
Update Experiment	2.0/mlflow/experiments/update	POST	can_update
Search Experiments	2.0/mlflow/experiments/search	POST	None
Search Experiments	2.0/mlflow/experiments/search	GET	None
Set Experiment Tag	2.0/mlflow/experiments/set-experiment-tag	POST	can_update
Create Run	2.0/mlflow/runs/create	POST	can_update
Get Run	2.0/mlflow/runs/get	GET	can_read
Update Run	2.0/mlflow/runs/update	POST	can_update
Delete Run	2.0/mlflow/runs/delete	POST	can_delete
Restore Run	2.0/mlflow/runs/restore	POST	can_delete
Search Runs	2.0/mlflow/runs/search	POST	None
Set Tag	2.0/mlflow/runs/set-tag	POST	can_update
Delete Tag	2.0/mlflow/runs/delete-tag	POST	can_update
Log Metric	2.0/mlflow/runs/log-metric	POST	can_update
Log Param	2.0/mlflow/runs/log-parameter	POST	can_update
Log Batch	2.0/mlflow/runs/log-batch	POST	can_update
Log Model	2.0/mlflow/runs/log-model	POST	can_update
List Artifacts	2.0/mlflow/artifacts/list	GET	can_read
Get Metric History	2.0/mlflow/metrics/get-history	GET	can_read

Required Permissions for accessing registered models:

API	Endpoint	Method	Required permission
Create Registered Model	2.0/mlflow/registered-models/create	POST	None
Rename Registered Model	2.0/mlflow/registered-models/rename	POST	can_update
Update Registered Model	2.0/mlflow/registered-models/update	PATCH	can_update
Delete Registered Model	2.0/mlflow/registered-models/delete	DELETE	can_delete
Get Registered Model	2.0/mlflow/registered-models/get	GET	can_read
Search Registered Models	2.0/mlflow/registered-models/search	GET	None
Get Latest Versions	2.0/mlflow/registered-models/get-latest-versions	POST	can_read
Get Latest Versions	2.0/mlflow/registered-models/get-latest-versions	GET	can_read
Set Registered Model Tag	2.0/mlflow/registered-models/set-tag	POST	can_update
Delete Registered Model Tag	2.0/mlflow/registered-models/delete-tag	DELETE	can_update
Set Registered Model Alias	2.0/mlflow/registered-models/alias	POST	can_update
Delete Registered Model Alias	2.0/mlflow/registered-models/alias	DELETE	can_delete
Get Model Version By Alias	2.0/mlflow/registered-models/alias	GET	can_read
Create Model Version	2.0/mlflow/model-versions/create	POST	can_update
Update Model Version	2.0/mlflow/model-versions/update	PATCH	can_update
Transition Model Version Stage	2.0/mlflow/model-versions/transition-stage	POST	can_update
Delete Model Version	2.0/mlflow/model-versions/delete	DELETE	can_delete
Get Model Version	2.0/mlflow/model-versions/get	GET	can_read
Search Model Versions	2.0/mlflow/model-versions/search	GET	None
Get Model Version Download Uri	2.0/mlflow/model-versions/get-download-uri	GET	can_read
Set Model Version Tag	2.0/mlflow/model-versions/set-tag	POST	can_update
Delete Model Version Tag	2.0/mlflow/model-versions/delete-tag	DELETE	can_delete

MLflow Authentication introduces several new API endpoints to manage users and permissions.

API	Endpoint	Method	Required permission
Create User	2.0/mlflow/users/create	POST	None
Get User	2.0/mlflow/users/get	GET	Only readable by that user
Update User Password	2.0/mlflow/users/update-password	PATCH	Only updatable by that user
Update User Admin	2.0/mlflow/users/update-admin	PATCH	Only admin
Delete User	2.0/mlflow/users/delete	DELETE	Only admin
Create Experiment Permission	2.0/mlflow/experiments/permissions/create	POST	can_manage
Get Experiment Permission	2.0/mlflow/experiments/permissions/get	GET	can_manage
Update Experiment Permission	2.0/mlflow/experiments/permissions/update	PATCH	can_manage
Delete Experiment Permission	2.0/mlflow/experiments/permissions/delete	DELETE	can_manage
Create Registered Model Permission	2.0/mlflow/registered-models/permissions/create	POST	can_manage
Get Registered Model Permission	2.0/mlflow/registered-models/permissions/get	GET	can_manage
Update Registered Model Permission	2.0/mlflow/registered-models/permissions/update	PATCH	can_manage
Delete Registered Model Permission	2.0/mlflow/registered-models/permissions/delete	DELETE	can_manage

Some APIs will also have their behaviour modified. For example, the creator of an experiment will automatically be granted MANAGE permission on that experiment, so that the creator can grant or revoke other users’ access to that experiment.

API	Endpoint	Method	Effect
Create Experiment	2.0/mlflow/experiments/create	POST	Automatically grants MANAGE permission to the creator.
Create Registered Model	2.0/mlflow/registered-models/create	POST	Automatically grants MANAGE permission to the creator.
Search Experiments	2.0/mlflow/experiments/search	POST	Only returns experiments which the user has READ permission on.
Search Experiments	2.0/mlflow/experiments/search	GET	Only returns experiments which the user has READ permission on.
Search Runs	2.0/mlflow/runs/search	POST	Only returns experiments which the user has READ permission on.
Search Registered Models	2.0/mlflow/registered-models/search	GET	Only returns registered models which the user has READ permission on.
Search Model Versions	2.0/mlflow/model-versions/search	GET	Only returns registered models which the user has READ permission on.

Permissions Database

All users and permissions are stored in a database in basic_auth.db, relative to the directory where MLflow server is launched. The location can be changed in the configuration file. To run migrations, use the following command:

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

Admin Users

Admin users have unrestricted access to all MLflow resources, including creating or deleting users, updating password and admin status of other users, granting or revoking permissions from other users, and managing permissions for all MLflow resources, even if NO_PERMISSIONS is explicitly set to that admin account.

MLflow has a built-in admin user that will be created the first time that the MLflow authentication feature is enabled.

Note

It is recommended that you update the default admin password as soon as possible after creation.

The default admin user credentials are as follows:

Username	Password
admin	password

Multiple admin users can exist by promoting other users to admin, using the 2.0/mlflow/users/update-admin endpoint.

Example

# authenticate as built-in admin user
export MLFLOW_TRACKING_USERNAME=admin
export MLFLOW_TRACKING_PASSWORD=password

from mlflow.server import get_app_client

tracking_uri = "http://localhost:5000/"

auth_client = get_app_client("basic-auth", tracking_uri=tracking_uri)
auth_client.create_user(username="user1", password="pw1")
auth_client.update_user_admin(username="user1", is_admin=True)

Managing Permissions

MLflow provides REST APIs and a client class AuthServiceClient to manage users and permissions. To instantiate AuthServiceClient, it is recommended that you use mlflow.server.get_app_client().

Example

export MLFLOW_TRACKING_USERNAME=admin
export MLFLOW_TRACKING_PASSWORD=password

from mlflow import MlflowClient
from mlflow.server import get_app_client

tracking_uri = "http://localhost:5000/"

auth_client = get_app_client("basic-auth", tracking_uri=tracking_uri)
auth_client.create_user(username="user1", password="pw1")
auth_client.create_user(username="user2", password="pw2")

client = MlflowClient(tracking_uri=tracking_uri)
experiment_id = client.create_experiment(name="experiment")

auth_client.create_experiment_permission(
    experiment_id=experiment_id, username="user2", permission="MANAGE"
)

Authenticating to MLflow

Using MLflow UI

When a user first visits the MLflow UI on a browser, they will be prompted to login. There is no limit to how many login attempts can be made.

Currently, MLflow UI does not display any information about the current user. Once a user is logged in, the only way to log out is to close the browser.

Using Environment Variables

MLflow provides two environment variables for authentication: MLFLOW_TRACKING_USERNAME and MLFLOW_TRACKING_PASSWORD. To use basic authentication, you must set both environment variables.

export MLFLOW_TRACKING_USERNAME=username
export MLFLOW_TRACKING_PASSWORD=password

import mlflow

mlflow.set_tracking_uri("https://<mlflow_tracking_uri>/")
with mlflow.start_run():
    ...

Using Credentials File

You can save your credentials in a file to remove the need for setting environment variables every time. The credentials should be saved in ~/.mlflow/credentials using INI format. Note that the password will be stored unencrypted on disk, and is protected only by filesystem permissions.

If the environment variables MLFLOW_TRACKING_USERNAME and MLFLOW_TRACKING_PASSWORD are configured, they override any credentials provided in the credentials file.

Credentials file format

[mlflow]
mlflow_tracking_username = username
mlflow_tracking_password = password

Using REST API

A user can authenticate using the HTTP Authorization request header. See https://developer.mozilla.org/en-US/docs/Web/HTTP/Authentication for more information.

In Python, you can use the requests library:

import requests

response = requests.get(
    "https://<mlflow_tracking_uri>/",
    auth=("username", "password"),
)

Creating a New User

Important

To create a new user, you are required to authenticate with admin privileges.

Using MLflow UI

MLflow UI provides a simple page for creating new users at <tracking_uri>/signup.

Using REST API

Alternatively, you can send POST requests to the Tracking Server endpoint 2.0/users/create.

In Python, you can use the requests library:

import requests

response = requests.post(
    "https://<mlflow_tracking_uri>/api/2.0/mlflow/users/create",
    json={
        "username": "username",
        "password": "password",
    },
)

Using MLflow AuthServiceClient

MLflow AuthServiceClient provides a function to create new users easily.

import mlflow

auth_client = mlflow.server.get_app_client(
    "basic-auth", tracking_uri="https://<mlflow_tracking_uri>/"
)
auth_client.create_user(username="username", password="password")

Configuration

Authentication configuration is located at mlflow/server/auth/basic_auth.ini:

Variable	Description
default_permission	Default permission on all resources
database_uri	Database location to store permission and user data
admin_username	Default admin username if the admin is not already created
admin_password	Default admin password if the admin is not already created
authorization_function	Function to authenticate requests

Alternatively, assign the environment variable MLFLOW_AUTH_CONFIG_PATH to point to your custom configuration file.

The authorization_function setting supports pluggable authentication methods if you want to use another authentication method than HTTP basic auth. The value specifies module_name:function_name. The function has the following signature:

def authenticate_request() -> Union[Authorization, Response]:
    ...

The function should return a werkzeug.datastructures.Authorization object if the request is authenticated, or a Response object (typically 401: Unauthorized) if the request is not authenticated. For an example of how to implement a custom authentication method, see tests/server/auth/jwt_auth.py. NOTE: This example is not intended for production use.

Connecting to a Centralized Database

By default, MLflow Authentication uses a local SQLite database to store user and permission data. In the case of a multi-node deployment, it is recommended to use a centralized database to store this data.

To connect to a centralized database, you can set the database_uri configuration variable to the database URL.

Example: /path/to/my_auth_config.ini

[mlflow]
database_uri = postgresql://username:password@hostname:port/database

Then, start the MLflow server with the MLFLOW_AUTH_CONFIG_PATH environment variable set to the path of your configuration file.

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

The database must be created before starting the MLflow server. The database schema will be created automatically when the server starts.

Custom Authentication

MLflow authentication is designed to be extensible. If your organization desires more advanced authentication logic (e.g., token-based authentication), it is possible to install a third party plugin or to create your own plugin.

Your plugin should be an installable Python package. It should include an app factory that extends the MLflow app and, optionally, implement a client to manage permissions. The app factory function name will be passed to the --app argument in Flask CLI. See https://flask.palletsprojects.com/en/latest/cli/#application-discovery for more information.

Example: my_auth/__init__.py

from flask import Flask
from mlflow.server import app


def create_app(app: Flask = app):
    app.add_url_rule(...)
    return app


class MyAuthClient:
    ...

Then, the plugin should be installed in your Python environment:

pip install my_auth

Then, register your plugin in mlflow/setup.py:

setup(
    ...,
    entry_points="""
        ...

        [mlflow.app]
        my-auth=my_auth:create_app

        [mlflow.app.client]
        my-auth=my_auth:MyAuthClient
    """,
)

Then, you can start the MLflow server:

mlflow server --app-name my-auth