MLflow client compatibility

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Introduced in GitLab 15.11.

Generally available in GitLab 17.8.

MLflow is a popular open source tool for Machine Learning experiment tracking. GitLab Model experiment tracking and GitLab Model registry are compatible with the MLflow client. The setup requires minimal changes to existing code.

GitLab plays the role of a MLflow server. Running mlflow server is not necessary.

Enable MLflow client integration

Prerequisites:

A personal, project, or group access token with at least the Developer role and the api scope.
The project ID. To find the project ID:
1. On the left sidebar, select Search or go to and find your project.
2. Select Settings > General.

To use MLflow client compatibility from a local environment:

Set the tracking URI and token environment variables on the host that runs the code. This can be your local environment, CI pipeline, or remote host. For example:
```
export MLFLOW_TRACKING_URI="<your gitlab endpoint>/api/v4/projects/<your project id>/ml/mlflow"
export MLFLOW_TRACKING_TOKEN="<your_access_token>"
```
If the training code contains the call to mlflow.set_tracking_uri(), remove it.

In the model registry, you can copy the tracking URI from the overflow menu in the top right by selecting the vertical ellipsis ({ellipsis_v}).

Model experiments

When running the training code, MLflow client can be used to create experiments, runs, models, model versions, log parameters, metrics, metadata, and artifacts on GitLab.

After experiments are logged, they are listed under /<your project>/-/ml/experiments.

Runs are registered and can be explored by selecting an experiment, model, or model version.

Associating a run to a CI/CD job

Introduced in GitLab 16.1.

Changed to beta in GitLab 17.1.

If your training code is being run from a CI/CD job, GitLab can use that information to enhance run metadata. To associate a run to a CI/CD job:

In the Project CI variables, include the following variables:
- MLFLOW_TRACKING_URI: "<your gitlab endpoint>/api/v4/projects/<your project id>/ml/mlflow"
- MLFLOW_TRACKING_TOKEN: <your_access_token>

In your training code within the run execution context, add the following code snippet:

import os
import mlflow

with mlflow.start_run(run_name=f"Run {index}"):
  # Your training code

  # Start of snippet to be included
  if os.getenv('GITLAB_CI'):
    mlflow.set_tag('gitlab.CI_JOB_ID', os.getenv('CI_JOB_ID'))
  # End of snippet to be included

Model registry

You can also manage models and model versions by using the MLflow client. Models are registered under /<your project>/-/ml/models.

Models

Creating a model

from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
description = 'Model description'
model = client.create_registered_model(model_name, description=description)

Notes

create_registered_model argument tags is ignored.
name must be unique within the project.
name cannot be the name of an existing experiment.

Fetching a model

from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
model = client.get_registered_model(model_name)

Updating a model

from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
description = 'New description'
client.update_registered_model(model_name, description=description)

Deleting a model

from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
client.delete_registered_model(model_name)

Logging runs to a model

Every model has an associated experiment with the same name prefixed by [model]. To log a run to the model, use the experiment passing the correct name:

from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
exp = client.get_experiment_by_name(f"[model]{model_name}")
run = client.create_run(exp.experiment_id)

Model version

Creating a model version

from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
description = 'Model version description'
model_version = client.create_model_version(model_name, source="", description=description)

If the version parameter is not passed, it will be auto-incremented from the latest uploaded version. You can set the version by passing a tag during model version creation. The version must follow SemVer format.

from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
version = '<your_version>'
tags = { "gitlab.version": version }
client.create_model_version(model_name, version, description=description, tags=tags)

Notes

Argument run_id is ignored. Every model version behaves as a run. Creating a mode version from a run is not yet supported.
Argument source is ignored. GitLab will create a package location for the model version files.
Argument run_link is ignored.
Argument await_creation_for is ignored.

Updating a model

from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
version = '<your_version>'
description = 'New description'
client.update_model_version(model_name, version, description=description)

Fetching a model version

from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
version = '<your_version>'
client.get_model_version(model_name, version)

Getting latest versions of a model

from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
client.get_latest_versions(model_name)

Notes

Argument stages is ignored.
Versions are ordered by highest semantic version.

Loading a model version

from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
model = client.get_registered_model(model_name)
```0

#### Logging metrics and parameters to a model version

Every model version is also a run, allowing users to log parameters
and metrics. The run ID can either be found at the Model version page in GitLab,
or by using the MLflow client:

```python
from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
model = client.get_registered_model(model_name)
```1

#### Logging artifacts to a model version

GitLab creates a package that can be used by the MLflow client to upload files.

```python
from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
model = client.get_registered_model(model_name)
```2

Artifacts will then be available under `https/<your project>/-/ml/models/<model_id>/versions/<version_id>`.

#### Linking a model version to a CI/CD job

Similar to runs, it is also possible to link a model version to a CI/CD job:

```python
from mlflow import MlflowClient

client = MlflowClient()
model_name = '<your_model_name>'
model = client.get_registered_model(model_name)
```3

## Supported MLflow client methods and caveats

GitLab supports these methods from the MLflow client. Other methods might be supported but were not
tested. More information can be found in the [MLflow Documentation](https://www.mlflow.org/docs/1.28.0/python_api/mlflow.html). The MlflowClient counterparts
of the methods below are also supported with the same caveats.

| Method                   | Supported       | Version Added | Comments                                                                                     |
|--------------------------|-----------------|---------------|----------------------------------------------------------------------------------------------|
| `create_experiment`      | Yes             | 15.11         |                                                                                              |
| `get_experiment`         | Yes             | 15.11         |                                                                                              |
| `get_experiment_by_name` | Yes             | 15.11         |                                                                                              |
| `delete_experiment`      | Yes             | 17.5          |                                                                                              |
| `set_experiment`         | Yes             | 15.11         |                                                                                              |
| `get_run`                | Yes             | 15.11         |                                                                                              |
| `delete_run`             | Yes             | 17.5          |                                                                                              |
| `start_run`              | Yes             | 15.11         | (16.3) If a name is not provided, the run receives a random nickname.                        |
| `search_runs`            | Yes             | 15.11         | (16.4) `experiment_ids` supports only a single experiment ID with order by column or metric. |
| `log_artifact`           | Yes with caveat | 15.11         | (15.11) `artifact_path` must be empty. Does not support directories.                         |
| `log_artifacts`          | Yes with caveat | 15.11         | (15.11) `artifact_path` must be empty. Does not support directories.                         |
| `log_batch`              | Yes             | 15.11         |                                                                                              |
| `log_metric`             | Yes             | 15.11         |                                                                                              |
| `log_metrics`            | Yes             | 15.11         |                                                                                              |
| `log_param`              | Yes             | 15.11         |                                                                                              |
| `log_params`             | Yes             | 15.11         |                                                                                              |
| `log_figure`             | Yes             | 15.11         |                                                                                              |
| `log_image`              | Yes             | 15.11         |                                                                                              |
| `log_text`               | Yes with caveat | 15.11         | (15.11) Does not support directories.                                                        |
| `log_dict`               | Yes with caveat | 15.11         | (15.11) Does not support directories.                                                        |
| `set_tag`                | Yes             | 15.11         |                                                                                              |
| `set_tags`               | Yes             | 15.11         |                                                                                              |
| `set_terminated`         | Yes             | 15.11         |                                                                                              |
| `end_run`                | Yes             | 15.11         |                                                                                              |
| `update_run`             | Yes             | 15.11         |                                                                                              |
| `log_model`              | Partial         | 15.11         | (15.11) Saves the artifacts, but not the model data. `artifact_path` must be empty.          |
| `load_model`             | Yes             | 17.5          |                                                                                              |

Other MLflowClient methods:

| Method                    | Supported        | Version added | Comments                                         |
|---------------------------|------------------|---------------|--------------------------------------------------|
| `create_registered_model` | Yes with caveats | 16.8          | [See notes](#creating-a-model)                   |
| `get_registered_model`    | Yes              | 16.8          |                                                  |
| `delete_registered_model` | Yes              | 16.8          |                                                  |
| `update_registered_model` | Yes              | 16.8          |                                                  |
| `create_model_version`    | Yes with caveats | 16.8          | [See notes](#creating-a-model-version)           |
| `get_model_version`       | Yes              | 16.8          |                                                  |
| `get_latest_versions`     | Yes with caveats | 16.8          | [See notes](#getting-latest-versions-of-a-model) |
| `update_model_version`    | Yes              | 16.8          |                                                  |
| `create_registered_model` | Yes              | 16.8          |                                                  |
| `create_registered_model` | Yes              | 16.8          |                                                  |

## Known issues

- The API GitLab supports is the one defined at MLflow version 2.7.1.
- MLflow client methods not listed above are not supported.
- During creation of experiments and runs, ExperimentTags are stored, even though they are not displayed.