Attach metadata to an artifact

Learn how to attach metadata to an artifact.

Metadata in the dashboard

In ZenML, metadata enhances artifacts by adding context and important details, such as size, structure, or performance metrics. This metadata is accessible in the ZenML dashboard, making it easier to inspect, compare, and track artifacts across pipeline runs.

Logging Metadata for Artifacts

Artifacts in ZenML are outputs of steps within a pipeline, such as datasets, models, or evaluation results. Associating metadata with artifacts can help users understand the nature and characteristics of these outputs.

To log metadata for an artifact, use the log_metadata function, specifying the artifact name, version, or ID. The metadata can be any JSON-serializable value, including ZenML custom types like Uri, Path, DType, and StorageSize. Find out more about these different types here.

Here's an example of logging metadata for an artifact:

import pandas as pd

from zenml import step, log_metadata
from zenml.metadata.metadata_types import StorageSize


@step
def process_data_step(dataframe: pd.DataFrame) -> pd.DataFrame:
    """Process a dataframe and log metadata about the result."""
    processed_dataframe = ...

    # Log metadata about the processed dataframe
    log_metadata(
        metadata={
            "row_count": len(processed_dataframe),
            "columns": list(processed_dataframe.columns),
            "storage_size": StorageSize(
                processed_dataframe.memory_usage().sum())
        },
        infer_artifact=True,
    )
    return processed_dataframe

Selecting the artifact to log the metadata to

When using log_metadata with an artifact name, ZenML provides flexible options to attach metadata to the correct artifact:

1. Using infer_artifact: If used within a step, ZenML will use the step context to infer the outputs artifacts of the step. If the step has only one output, this artifact will be selected. However, if you additionally provide an artifact_name, ZenML will search for this name in the output space of the step (useful for step with multiple outputs).

2. Name and Version Provided: If both an artifact name and version are provided, ZenML will use these to identify and attach metadata to the specific artifact version.

3. Artifact Version ID Provided: If an artifact version ID is provided directly, ZenML will use it to fetch and attach the metadata to that specific artifact version.

Fetching logged metadata

Once metadata has been logged in an artifact, or step, we can easily fetch the metadata with the ZenML Client:

from zenml.client import Client

client = Client()
artifact = client.get_artifact_version("my_artifact", "my_version")

print(artifact.run_metadata["metadata_key"])

When you are fetching metadata using a specific key, the returned value will always reflect the latest entry.

Grouping Metadata in the Dashboard

When logging metadata passing a dictionary of dictionaries in the metadata parameter will group the metadata into cards in the ZenML dashboard. This feature helps organize metadata into logical sections, making it easier to visualize and understand.

Here's an example of grouping metadata into cards:

from zenml import log_metadata

from zenml.metadata.metadata_types import StorageSize

log_metadata(
    metadata={
        "model_metrics": {
            "accuracy": 0.95,
            "precision": 0.92,
            "recall": 0.90
        },
        "data_details": {
            "dataset_size": StorageSize(1500000),
            "feature_columns": ["age", "income", "score"]
        }
    },
    artifact_name="my_artifact",
    artifact_version="version",
)

In the ZenML dashboard, model_metrics and data_details would appear as separate cards, each containing their respective key-value pairs.