Filesystems¶
A filesystem block is an object that allows you to read and write data from paths. Prefect provides multiple built-in file system types that cover a wide range of use cases.
Additional file system types are available in Prefect Collections.
Local filesystem¶
The LocalFileSystem block enables interaction with the files in your current development environment.
LocalFileSystem properties include:
| Property | Description |
|---|---|
| basepath | String path to the location of files on the local filesystem. Access to files outside of the base path will not be allowed. |
from prefect.filesystems import LocalFileSystem
fs = LocalFileSystem(basepath="/foo/bar")
Limited access to local file system
Be aware that LocalFileSystem access is limited to the exact path provided. This file system may not be ideal for some use cases. The execution environment for your workflows may not have the same file system as the environment you are writing and deploying your code on.
Use of this file system can limit the availability of results after a flow run has completed or prevent the code for a flow from being retrieved successfully at the start of a run.
Remote file system¶
The RemoteFileSystem block enables interaction with arbitrary remote file systems. Under the hood, RemoteFileSystem uses fsspec and supports any file system that fsspec supports.
RemoteFileSystem properties include:
| Property | Description |
|---|---|
| basepath | String path to the location of files on the remote filesystem. Access to files outside of the base path will not be allowed. |
| settings | Dictionary containing extra parameters required to access the remote file system. |
The file system is specified using a protocol:
s3://my-bucket/my-folder/will use S3gcs://my-bucket/my-folder/will use GCSaz://my-bucket/my-folder/will use Azure
For example, to use it with Amazon S3:
from prefect.filesystems import RemoteFileSystem
block = RemoteFileSystem(basepath="s3://my-bucket/folder/")
block.save("dev")
You may need to install additional libraries to use some remote storage types.
RemoteFileSystem examples¶
How can we use RemoteFileSystem to store our flow code? The following is a use case where we use MinIO as a storage backend:
from prefect.filesystems import RemoteFileSystem
minio_block = RemoteFileSystem(
basepath="s3://my-bucket",
settings={
"key": "MINIO_ROOT_USER",
"secret": "MINIO_ROOT_PASSWORD",
"client_kwargs": {"endpoint_url": "http://localhost:9000"},
},
)
minio_block.save("minio")
Azure¶
The Azure file system block enables interaction with Azure Datalake and Azure Blob Storage. Under the hood, the Azure block uses adlfs.
Azure properties include:
| Property | Description |
|---|---|
| bucket_path | String path to the location of files on the remote filesystem. Access to files outside of the bucket path will not be allowed. |
| azure_storage_connection_string | Azure storage connection string. |
| azure_storage_account_name | Azure storage account name. |
| azure_storage_account_key | Azure storage account key. |
| azure_storage_tenant_id | Azure storage tenant ID. |
| azure_storage_client_id | Azure storage client ID. |
| azure_storage_client_secret | Azure storage client secret. |
| azure_storage_anon | Anonymous authentication, disable to use DefaultAzureCredential. |
To create a block:
from prefect.filesystems import Azure
block = Azure(bucket_path="my-bucket/folder/")
block.save("dev")
To use it in a deployment:
prefect deployment build path/to/flow.py:flow_name --name deployment_name --tag dev -sb az/dev
You need to install adlfs to use it.
GitHub¶
The GitHub filesystem block enables interaction with GitHub repositories. This block is read-only and works with both public and private repositories.
GitHub properties include:
| Property | Description |
|---|---|
| reference | An optional reference to pin to, such as a branch name or tag. |
| repository | The URL of a GitHub repository to read from, in either HTTPS or SSH format. |
| access_token | A GitHub Personal Access Token (PAT) with repo scope. |
To create a block:
from prefect.filesystems import GitHub
block = GitHub(
repository="https://github.com/my-repo/",
access_token=<my_access_token> # only required for private repos
)
block.get_directory("folder-in-repo") # specify a subfolder of repo
block.save("dev")
To use it in a deployment:
prefect deployment build path/to/flow.py:flow_name --name deployment_name --tag dev -sb github/dev -a
GitLabRepository¶
The GitLabRepository block is read-only and works with private GitLab repositories.
GitLabRepository properties include:
| Property | Description |
|---|---|
| reference | An optional reference to pin to, such as a branch name or tag. |
| repository | The URL of a GitLab repository to read from, in either HTTPS or SSH format. |
| credentials | A GitLabCredentials block with Personal Access Token (PAT) with read_repository scope. |
To create a block:
from prefect_gitlab.credentials import GitLabCredentials
from prefect_gitlab.repositories import GitLabRepository
gitlab_creds = GitLabCredentials(token="YOUR_GITLAB_ACCESS_TOKEN")
gitlab_repo = GitLabRepository(
repository="https://gitlab.com/yourorg/yourrepo.git",
reference="main",
credentials=gitlab_creds,
)
gitlab_repo.save("dev")
To use it in a deployment (and apply):
prefect deployment build path/to/flow.py:flow_name --name deployment_name --tag dev -sb gitlab-repository/dev -a
Note that to use this block, you need to install the prefect-gitlab collection.
GCS¶
The GCS file system block enables interaction with Google Cloud Storage. Under the hood, GCS uses gcsfs.
GCS properties include:
| Property | Description |
|---|---|
| bucket_path | A GCS bucket path |
| service_account_info | The contents of a service account keyfile as a JSON string. |
| project | The project the GCS bucket resides in. If not provided, the project will be inferred from the credentials or environment. |
To create a block:
from prefect.filesystems import GCS
block = GCS(bucket_path="my-bucket/folder/")
block.save("dev")
To use it in a deployment:
prefect deployment build path/to/flow.py:flow_name --name deployment_name --tag dev -sb gcs/dev
You need to install gcsfsto use it.
S3¶
The S3 file system block enables interaction with Amazon S3. Under the hood, S3 uses s3fs.
S3 properties include:
| Property | Description |
|---|---|
| bucket_path | An S3 bucket path |
| aws_access_key_id | AWS Access Key ID |
| aws_secret_access_key | AWS Secret Access Key |
To create a block:
from prefect.filesystems import S3
block = S3(bucket_path="my-bucket/folder/")
block.save("dev")
To use it in a deployment:
prefect deployment build path/to/flow.py:flow_name --name deployment_name --tag dev -sb s3/dev
You need to install s3fsto use this block.
SMB¶
The SMB file system block enables interaction with SMB shared network storage. Under the hood, SMB uses smbprotocol. Used to connect to Windows-based SMB shares from Linux-based Prefect flows. The SMB file system block is able to copy files, but cannot create directories.
SMB properties include:
| Property | Description |
|---|---|
| basepath | String path to the location of files on the remote filesystem. Access to files outside of the base path will not be allowed. |
| smb_host | Hostname or IP address where SMB network share is located. |
| smb_port | Port for SMB network share (defaults to 445). |
| smb_username | SMB username with read/write permissions. |
| smb_password | SMB password. |
To create a block:
from prefect.filesystems import SMB
block = SMB(basepath="my-share/folder/")
block.save("dev")
To use it in a deployment:
prefect deployment build path/to/flow.py:flow_name --name deployment_name --tag dev -sb smb/dev
You need to install smbprotocol to use it.
Handling credentials for cloud object storage services¶
If you leverage S3, GCS, or Azure storage blocks, and you don't explicitly configure credentials on the respective storage block, those credentials will be inferred from the environment. Make sure to set those either explicitly on the block or as environment variables, configuration files, or IAM roles within both the build and runtime environment for your deployments.
Filesystem package dependencies¶
A Prefect installation and doesn't include filesystem-specific package dependencies such as s3fs, gcsfs or adlfs. This includes Prefect base Docker images.
You must ensure that filesystem-specific libraries are installed in an execution environment where they will be used by flow runs.
In Dockerized deployments, you can leverage the EXTRA_PIP_PACKAGES environment variable. Those dependencies will be installed at runtime within your Docker container or Kubernetes Job before the flow starts running.
Here is an example from a deployment YAML file showing how to specify the installation of s3fs from into your image:
infrastructure:
type: docker-container
env:
EXTRA_PIP_PACKAGES: s3fs # could be gcsfs, adlfs, etc.
You may specify multiple dependencies by providing a comma-delimted list.
Saving and loading file systems¶
Configuration for a file system can be saved to the Prefect API. For example:
fs = RemoteFileSystem(basepath="s3://my-bucket/folder/")
fs.write_path("foo", b"hello")
fs.save("dev-s3")
This file system can be retrieved for later use with load.
fs = RemoteFileSystem.load("dev-s3")
fs.read_path("foo") # b'hello'
Readable and writable file systems¶
Prefect provides two abstract file system types, ReadableFileSystem and WriteableFileSystem.
- All readable file systems must implement
read_path, which takes a file path to read content from and returns bytes. - All writeable file systems must implement
write_pathwhich takes a file path and content and writes the content to the file as bytes.
A file system may implement both of these types.