Using MLflow with Tune#

MLflow is an open source platform to manage the ML lifecycle, including experimentation, reproducibility, deployment, and a central model registry. It currently offers four components, including MLflow Tracking to record and query experiments, including code, data, config, and results.

Ray Tune currently offers two lightweight integrations for MLflow Tracking. One is the MLflowLoggerCallback, which automatically logs metrics reported to Tune to the MLflow Tracking API.

The other one is the setup_mlflow function, which can be used with the function API. It automatically initializes the MLflow API with Tune’s training information and creates a run for each Tune trial. Then within your training function, you can just use the MLflow like you would normally do, e.g. using mlflow.log_metrics() or even mlflow.autolog() to log to your training process.

Running an MLflow Example#

In the following example we’re going to use both of the above methods, namely the MLflowLoggerCallback and the setup_mlflow function to log metrics. Let’s start with a few crucial imports:

import os
import tempfile
import time

import mlflow

from ray import tune
from ray.air.integrations.mlflow import MLflowLoggerCallback, setup_mlflow

Next, let’s define an easy training function (a Tune Trainable) that iteratively computes steps and evaluates intermediate scores that we report to Tune.

def evaluation_fn(step, width, height):
    return (0.1 + width * step / 100) ** (-1) + height * 0.1


def train_function(config):
    width, height = config["width"], config["height"]

    for step in range(config.get("steps", 100)):
        # Iterative training function - can be any arbitrary training procedure
        intermediate_score = evaluation_fn(step, width, height)
        # Feed the score back to Tune.
        tune.report({"iterations": step, "mean_loss": intermediate_score})
        time.sleep(0.1)

Given an MLFlow tracking URI, you can now simply use the MLflowLoggerCallback as a callback argument to your RunConfig():

def tune_with_callback(mlflow_tracking_uri, finish_fast=False):
    tuner = tune.Tuner(
        train_function,
        tune_config=tune.TuneConfig(num_samples=5),
        run_config=tune.RunConfig(
            name="mlflow",
            callbacks=[
                MLflowLoggerCallback(
                    tracking_uri=mlflow_tracking_uri,
                    experiment_name="mlflow_callback_example",
                    save_artifact=True,
                )
            ],
        ),
        param_space={
            "width": tune.randint(10, 100),
            "height": tune.randint(0, 100),
            "steps": 5 if finish_fast else 100,
        },
    )
    results = tuner.fit()

To use the setup_mlflow utility, you simply call this function in your training function. Note that we also use mlflow.log_metrics(...) to log metrics to MLflow. Otherwise, this version of our training function is identical to its original.

def train_function_mlflow(config):
    tracking_uri = config.pop("tracking_uri", None)
    setup_mlflow(
        config,
        experiment_name="setup_mlflow_example",
        tracking_uri=tracking_uri,
    )

    # Hyperparameters
    width, height = config["width"], config["height"]

    for step in range(config.get("steps", 100)):
        # Iterative training function - can be any arbitrary training procedure
        intermediate_score = evaluation_fn(step, width, height)
        # Log the metrics to mlflow
        mlflow.log_metrics(dict(mean_loss=intermediate_score), step=step)
        # Feed the score back to Tune.
        tune.report({"iterations": step, "mean_loss": intermediate_score})
        time.sleep(0.1)

With this new objective function ready, you can now create a Tune run with it as follows:

def tune_with_setup(mlflow_tracking_uri, finish_fast=False):
    # Set the experiment, or create a new one if does not exist yet.
    mlflow.set_tracking_uri(mlflow_tracking_uri)
    mlflow.set_experiment(experiment_name="setup_mlflow_example")

    tuner = tune.Tuner(
        train_function_mlflow,
        tune_config=tune.TuneConfig(num_samples=5),
        run_config=tune.RunConfig(
            name="mlflow",
        ),
        param_space={
            "width": tune.randint(10, 100),
            "height": tune.randint(0, 100),
            "steps": 5 if finish_fast else 100,
            "tracking_uri": mlflow.get_tracking_uri(),
        },
    )
    results = tuner.fit()

If you hapen to have an MLFlow tracking URI, you can set it below in the mlflow_tracking_uri variable and set smoke_test=False. Otherwise, you can just run a quick test of the tune_function and tune_decorated functions without using MLflow.

smoke_test = True

if smoke_test:
    mlflow_tracking_uri = os.path.join(tempfile.gettempdir(), "mlruns")
else:
    mlflow_tracking_uri = "<MLFLOW_TRACKING_URI>"

tune_with_callback(mlflow_tracking_uri, finish_fast=smoke_test)
if not smoke_test:
    df = mlflow.search_runs(
        [mlflow.get_experiment_by_name("mlflow_callback_example").experiment_id]
    )
    print(df)

tune_with_setup(mlflow_tracking_uri, finish_fast=smoke_test)
if not smoke_test:
    df = mlflow.search_runs(
        [mlflow.get_experiment_by_name("setup_mlflow_example").experiment_id]
    )
    print(df)

2022-12-22 10:37:53,580	INFO worker.py:1542 -- Started a local Ray instance. View the dashboard at http://127.0.0.1:8265 

Tune Status

Current time:	2022-12-22 10:38:04
Running for:	00:00:06.73
Memory:	10.4/16.0 GiB

System Info

Using FIFO scheduling algorithm.
Resources requested: 0/16 CPUs, 0/0 GPUs, 0.0/4.03 GiB heap, 0.0/2.0 GiB objects

Trial Status

Trial name	status	loc	height	width	loss	iter	total time (s)	iterations	neg_mean_loss
train_function_b275b_00000	TERMINATED	127.0.0.1:801	66	36	7.24935	5	0.587302	4	-7.24935
train_function_b275b_00001	TERMINATED	127.0.0.1:813	33	35	3.96667	5	0.507423	4	-3.96667
train_function_b275b_00002	TERMINATED	127.0.0.1:814	75	29	8.29365	5	0.518995	4	-8.29365
train_function_b275b_00003	TERMINATED	127.0.0.1:815	28	63	3.18168	5	0.567739	4	-3.18168
train_function_b275b_00004	TERMINATED	127.0.0.1:816	20	18	3.21951	5	0.526536	4	-3.21951

Trial Progress

Trial name	date	done	experiment_id	experiment_tag	hostname	iterations	iterations_since_restore	mean_loss	neg_mean_loss	node_ip	pid	time_since_restore	time_this_iter_s	time_total_s	timestamp	training_iteration	trial_id	warmup_time
train_function_b275b_00000	2022-12-22_10-38-01	True	28feaa4dd8ab4edab810e8109e77502e	0_height=66,width=36	kais-macbook-pro.anyscale.com.beta.tailscale.net	4	5	7.24935	-7.24935	127.0.0.1	801	0.587302	0.126818	0.587302	1671705481	5	b275b_00000	0.00293493
train_function_b275b_00001	2022-12-22_10-38-04	True	245010d0c3d0439ebfb664764ae9db3c	1_height=33,width=35	kais-macbook-pro.anyscale.com.beta.tailscale.net	4	5	3.96667	-3.96667	127.0.0.1	813	0.507423	0.122086	0.507423	1671705484	5	b275b_00001	0.00553799
train_function_b275b_00002	2022-12-22_10-38-04	True	898afbf9b906448c980f399c72a2324c	2_height=75,width=29	kais-macbook-pro.anyscale.com.beta.tailscale.net	4	5	8.29365	-8.29365	127.0.0.1	814	0.518995	0.123554	0.518995	1671705484	5	b275b_00002	0.0040431
train_function_b275b_00003	2022-12-22_10-38-04	True	03a4476f82734642b6ab0a5040ca58f8	3_height=28,width=63	kais-macbook-pro.anyscale.com.beta.tailscale.net	4	5	3.18168	-3.18168	127.0.0.1	815	0.567739	0.125471	0.567739	1671705484	5	b275b_00003	0.00406194
train_function_b275b_00004	2022-12-22_10-38-04	True	ff8c7c55ce6e404f9b0552c17f7a0c40	4_height=20,width=18	kais-macbook-pro.anyscale.com.beta.tailscale.net	4	5	3.21951	-3.21951	127.0.0.1	816	0.526536	0.123327	0.526536	1671705484	5	b275b_00004	0.00332022

2022-12-22 10:38:04,477	INFO tune.py:772 -- Total run time: 7.99 seconds (6.71 seconds for the tuning loop).

Tune Status

Current time:	2022-12-22 10:38:11
Running for:	00:00:07.00
Memory:	10.7/16.0 GiB

System Info

Using FIFO scheduling algorithm.
Resources requested: 0/16 CPUs, 0/0 GPUs, 0.0/4.03 GiB heap, 0.0/2.0 GiB objects

Trial Status

Trial name	status	loc	height	width	loss	iter	total time (s)	iterations	neg_mean_loss
train_function_mlflow_b73bd_00000	TERMINATED	127.0.0.1:842	37	68	4.05461	5	0.750435	4	-4.05461
train_function_mlflow_b73bd_00001	TERMINATED	127.0.0.1:853	50	20	6.11111	5	0.652748	4	-6.11111
train_function_mlflow_b73bd_00002	TERMINATED	127.0.0.1:854	38	83	4.0924	5	0.6513	4	-4.0924
train_function_mlflow_b73bd_00003	TERMINATED	127.0.0.1:855	15	93	1.76178	5	0.650586	4	-1.76178
train_function_mlflow_b73bd_00004	TERMINATED	127.0.0.1:856	75	43	8.04945	5	0.656046	4	-8.04945

Trial Progress

Trial name	date	done	experiment_id	experiment_tag	hostname	iterations	iterations_since_restore	mean_loss	neg_mean_loss	node_ip	pid	time_since_restore	time_this_iter_s	time_total_s	timestamp	training_iteration	trial_id	warmup_time
train_function_mlflow_b73bd_00000	2022-12-22_10-38-08	True	62703cfe82e54d74972377fbb525b000	0_height=37,width=68	kais-macbook-pro.anyscale.com.beta.tailscale.net	4	5	4.05461	-4.05461	127.0.0.1	842	0.750435	0.108625	0.750435	1671705488	5	b73bd_00000	0.0030272
train_function_mlflow_b73bd_00001	2022-12-22_10-38-11	True	03ea89852115465392ed318db8021614	1_height=50,width=20	kais-macbook-pro.anyscale.com.beta.tailscale.net	4	5	6.11111	-6.11111	127.0.0.1	853	0.652748	0.110796	0.652748	1671705491	5	b73bd_00001	0.00303078
train_function_mlflow_b73bd_00002	2022-12-22_10-38-11	True	3731fc2966f9453ba58c650d89035ab4	2_height=38,width=83	kais-macbook-pro.anyscale.com.beta.tailscale.net	4	5	4.0924	-4.0924	127.0.0.1	854	0.6513	0.108578	0.6513	1671705491	5	b73bd_00002	0.00310016
train_function_mlflow_b73bd_00003	2022-12-22_10-38-11	True	fb35841742b348b9912d10203c730f1e	3_height=15,width=93	kais-macbook-pro.anyscale.com.beta.tailscale.net	4	5	1.76178	-1.76178	127.0.0.1	855	0.650586	0.109097	0.650586	1671705491	5	b73bd_00003	0.0576491
train_function_mlflow_b73bd_00004	2022-12-22_10-38-11	True	6d3cbf9ecc3446369e607ff78c67bc29	4_height=75,width=43	kais-macbook-pro.anyscale.com.beta.tailscale.net	4	5	8.04945	-8.04945	127.0.0.1	856	0.656046	0.109869	0.656046	1671705491	5	b73bd_00004	0.00265694

2022-12-22 10:38:11,514	INFO tune.py:772 -- Total run time: 7.01 seconds (6.98 seconds for the tuning loop).

This completes our Tune and MLflow walk-through. In the following sections you can find more details on the API of the Tune-MLflow integration.

MLflow AutoLogging#

You can also check out here for an example on how you can leverage MLflow auto-logging, in this case with Pytorch Lightning

MLflow Logger API#

class ray.air.integrations.mlflow.MLflowLoggerCallback(tracking_uri: str | None = None, *, registry_uri: str | None = None, experiment_name: str | None = None, tags: Dict | None = None, tracking_token: str | None = None, save_artifact: bool = False)[source]

MLflow Logger to automatically log Tune results and config to MLflow.

MLflow (https://mlflow.org) Tracking is an open source library for recording and querying experiments. This Ray Tune LoggerCallback sends information (config parameters, training results & metrics, and artifacts) to MLflow for automatic experiment tracking.

Keep in mind that the callback will open an MLflow session on the driver and not on the trainable. Therefore, it is not possible to call MLflow functions like mlflow.log_figure() inside the trainable as there is no MLflow session on the trainable. For more fine grained control, use ray.air.integrations.mlflow.setup_mlflow().

Parameters:

tracking_uri – The tracking URI for where to manage experiments and runs. This can either be a local file path or a remote server. This arg gets passed directly to mlflow initialization. When using Tune in a multi-node setting, make sure to set this to a remote server and not a local file path.
registry_uri – The registry URI that gets passed directly to mlflow initialization.
experiment_name – The experiment name to use for this Tune run. If the experiment with the name already exists with MLflow, it will be reused. If not, a new experiment will be created with that name.
tags – An optional dictionary of string keys and values to set as tags on the run
tracking_token – Tracking token used to authenticate with MLflow.
save_artifact – If set to True, automatically save the entire contents of the Tune local_dir as an artifact to the corresponding run in MlFlow.

Example:

from ray.air.integrations.mlflow import MLflowLoggerCallback

tags = { "user_name" : "John",
         "git_commit_hash" : "abc123"}

tune.run(
    train_fn,
    config={
        # define search space here
        "parameter_1": tune.choice([1, 2, 3]),
        "parameter_2": tune.choice([4, 5, 6]),
    },
    callbacks=[MLflowLoggerCallback(
        experiment_name="experiment1",
        tags=tags,
        save_artifact=True)])

MLflow setup API#

Set up a MLflow session.

This function can be used to initialize an MLflow session in a (distributed) training or tuning run. The session will be created on the trainable.

By default, the MLflow experiment ID is the Ray trial ID and the MLlflow experiment name is the Ray trial name. These settings can be overwritten by passing the respective keyword arguments.

The config dict is automatically logged as the run parameters (excluding the mlflow settings).

In distributed training with Ray Train, only the zero-rank worker will initialize mlflow. All other workers will return a noop client, so that logging is not duplicated in a distributed run. This can be disabled by passing rank_zero_only=False, which will then initialize mlflow in every training worker.

This function will return the mlflow module or a noop module for non-rank zero workers if rank_zero_only=True. By using mlflow = setup_mlflow(config) you can ensure that only the rank zero worker calls the mlflow API.

Parameters:

config – Configuration dict to be logged to mlflow as parameters.
tracking_uri – The tracking URI for MLflow tracking. If using Tune in a multi-node setting, make sure to use a remote server for tracking.
registry_uri – The registry URI for the MLflow model registry.
experiment_id – The id of an already created MLflow experiment. All logs from all trials in tune.Tuner() will be reported to this experiment. If this is not provided or the experiment with this id does not exist, you must provide an``experiment_name``. This parameter takes precedence over experiment_name.
experiment_name – The name of an already existing MLflow experiment. All logs from all trials in tune.Tuner() will be reported to this experiment. If this is not provided, you must provide a valid experiment_id.
tracking_token – A token to use for HTTP authentication when logging to a remote tracking server. This is useful when you want to log to a Databricks server, for example. This value will be used to set the MLFLOW_TRACKING_TOKEN environment variable on all the remote training processes.
artifact_location – The location to store run artifacts. If not provided, MLFlow picks an appropriate default. Ignored if experiment already exists.
run_name – Name of the new MLflow run that will be created. If not set, will default to the experiment_name.
create_experiment_if_not_exists – Whether to create an experiment with the provided name if it does not already exist. Defaults to False.
tags – Tags to set for the new run.
rank_zero_only – If True, will return an initialized session only for the rank 0 worker in distributed training. If False, will initialize a session for all workers. Defaults to True.

Example

Per default, you can just call setup_mlflow and continue to use MLflow like you would normally do:

from ray.air.integrations.mlflow import setup_mlflow

def training_loop(config):
    mlflow = setup_mlflow(config)
    # ...
    mlflow.log_metric(key="loss", val=0.123, step=0)

In distributed data parallel training, you can utilize the return value of setup_mlflow. This will make sure it is only invoked on the first worker in distributed training runs.

from ray.air.integrations.mlflow import setup_mlflow

def training_loop(config):
    mlflow = setup_mlflow(config)
    # ...
    mlflow.log_metric(key="loss", val=0.123, step=0)

You can also use MlFlow’s autologging feature if using a training framework like Pytorch Lightning, XGBoost, etc. More information can be found here (https://mlflow.org/docs/latest/tracking.html#automatic-logging).

from ray.air.integrations.mlflow import setup_mlflow

def train_fn(config):
    mlflow = setup_mlflow(config)
    mlflow.autolog()
    xgboost_results = xgb.train(config, ...)

PublicAPI (alpha): This API is in alpha and may change before becoming stable.

More MLflow Examples#

MLflow PyTorch Lightning Example: Example for using MLflow and Pytorch Lightning with Ray Tune.