Artifact Stores

Setting up the storage for your artifacts

This is an older version of the ZenML documentation. To check the latest version please visit https://docs.zenml.io

In ZenML, all the inputs and outputs which go through a step are treated as artifacts and as its name suggests, an ArtifactStore is a place where these artifacts get stored.

Before reading this chapter, make sure that you are familiar with the concept of stacks, stack components and their flavors.

Base Abstraction

The artifact store establishes one of the main components in every ZenML stack. Now, let us take a deeper dive into the fundamentals behind its abstraction, namely the BaseArtifactStore:

1. As it is the base class for a specific type of StackComponent, it inherits from the StackComponent class. This sets the TYPE variable to a StackComponentType. The FLAVOR class variable needs to be set in the specific subclass.

2. As ZenML only supports filesystem-based artifact stores, it features an instance configuration parameter called path, which will indicate the root path of the artifact store. When creating an instance of any flavor of an ArtifactStore, users will have to define this parameter.

3. Moreover, there is an empty class variable called SUPPORTED_SCHEMES that needs to be defined in every flavor implementation. It indicates the supported filepath schemes for the corresponding implementation. For instance, for the Azure artifact store, this set will be defined as {"abfs://", "az://"}.

4. Lastly, the base class features a set of abstractmethods: open, copyfile,exists,glob,isdir,listdir,makedirs,mkdir,remove, rename,rmtree,stat,walk. In the implementation of every ArtifactStore flavor, it is required to define these methods with respect to the flavor at hand.

Putting all these considerations together, we end up with the following implementation:

from zenml.enums import StackComponentType
from zenml.stack import StackComponent

PathType = Union[bytes, str]

class BaseArtifactStore(StackComponent):
    """Base class for all ZenML artifact stores."""

    # --- Instance configuration ---
    path: str  # The root path of the artifact store.

    # --- Class variables ---
    TYPE: ClassVar[StackComponentType] = StackComponentType.ARTIFACT_STORE
    SUPPORTED_SCHEMES: ClassVar[Set[str]]

    # --- User interface ---
    @abstractmethod
    def open(self, name: PathType, mode: str = "r") -> Any:
        """Open a file at the given path."""

    @abstractmethod
    def copyfile(
        self, src: PathType, dst: PathType, overwrite: bool = False
    ) -> None:
        """Copy a file from the source to the destination."""

    @abstractmethod
    def exists(self, path: PathType) -> bool:
        """Returns `True` if the given path exists."""

    @abstractmethod
    def glob(self, pattern: PathType) -> List[PathType]:
        """Return the paths that match a glob pattern."""

    @abstractmethod
    def isdir(self, path: PathType) -> bool:
        """Returns whether the given path points to a directory."""

    @abstractmethod
    def listdir(self, path: PathType) -> List[PathType]:
        """Returns a list of files under a given directory in the filesystem."""

    @abstractmethod
    def makedirs(self, path: PathType) -> None:
        """Make a directory at the given path, recursively creating parents."""

    @abstractmethod
    def mkdir(self, path: PathType) -> None:
        """Make a directory at the given path; parent directory must exist."""

    @abstractmethod
    def remove(self, path: PathType) -> None:
        """Remove the file at the given path. Dangerous operation."""

    @abstractmethod
    def rename(
        self, src: PathType, dst: PathType, overwrite: bool = False
    ) -> None:
        """Rename source file to destination file."""

    @abstractmethod
    def rmtree(self, path: PathType) -> None:
        """Deletes dir recursively. Dangerous operation."""

    @abstractmethod
    def stat(self, path: PathType) -> Any:
        """Return the stat descriptor for a given file path."""

    @abstractmethod
    def walk(
        self,
        top: PathType,
        topdown: bool = True,
        onerror: Optional[Callable[..., None]] = None,
    ) -> Iterable[Tuple[PathType, List[PathType], List[PathType]]]:
        """Return an iterator that walks the contents of the given directory."""

This is a slimmed-down version of the base implementation which aims to highlight the abstraction layer. In order to see the full implementation and get the complete docstrings, please check the API docs.

The effect on the zenml.io.fileio

If you created an instance of an artifact store, added it to your stack and activated the stack, it will create a filesystem each time you run a ZenML pipeline and make it available to the zenml.io.fileio module.

This means that when you utilize a method such as fileio.open(...) with a filepath which starts with one of the SUPPORTED_SCHEMES within your steps or materializers, it will be able to use the open(...) method that you defined within your artifact store.

List of available artifact stores

Out of the box, ZenML comes with a LocalArtifactStore implementation, which is a simple implementation for a local setup.

Moreover, additional artifact stores can be found in specific integration modules, such as the GCPArtifactStore in the gcp integration and the AzureArtifactStore in the azure integration.

	Flavor	Integration
LocalArtifactStore	local	built-in
S3ArtifactStore	s3	s3
GCPArtifactStore	gcp	gcp
AzureArtifactStore	azure	azure

If you would like to see the available flavors for artifact stores, you can use the command:

zenml artifact-store flavor list

Build your own custom artifact store

If you want to create your own custom flavor for an artifact store, you can follow the following steps:

1. Create a class which inherits from the BaseArtifactStore.

2. Define the FLAVOR class variable.

3. Implement the abstactmethods based on your desired filesystem.

Once you are done with the implementation, you can register it through the CLI as:

zenml artifact-store flavor register <THE-SOURCE-PATH-OF-YOUR-ARTIFACT-STORE>