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Upload a file

This recipe uploads a file to a Unity Catalog volume using the Databricks SDK for Python.

Code snippet​

app.py
import reflex as rx
import io
from databricks.sdk import WorkspaceClient

w = WorkspaceClient()

def check_upload_permissions(volume_name: str):
    try:
        volume = w.volumes.read(name=volume_name)
        current_user = w.current_user.me()
        grants = w.grants.get_effective(
            securable_type="volume",
            full_name=volume.full_name,
            principal=current_user.user_name,
        )

        if not grants or not grants.privilege_assignments:
            return "Insufficient permissions: No grants found."

        for assignment in grants.privilege_assignments:
            for privilege in assignment.privileges:
                if privilege.privilege.value in ["ALL_PRIVILEGES", "WRITE_VOLUME"]:
                    return "Volume and permissions validated"

        return "Insufficient permissions: Required privileges not found."
    except Exception as e:
        return f"Error: {e}"

class UploadFileState(rx.State):
    upload_volume_path: str = ""
    volume_check_success: bool = False
    permission_result: str = ""
    is_checking: bool = False
    is_uploading: bool = False
    uploaded_files: list[str] = []

    @rx.event
    async def check_volume_permissions(self):
        self.is_checking = True
        self.permission_result = ""
        self.volume_check_success = False
        yield

        result = check_upload_permissions(self.upload_volume_path)

        self.permission_result = result
        if "validated" in result:
            self.volume_check_success = True
        self.is_checking = False

    @rx.event
    async def handle_upload(self, files: list[rx.UploadFile]):
        if not files: return
        self.is_uploading = True
        yield
        try:
            parts = self.upload_volume_path.strip().split(".")
            catalog, schema, volume_name = parts[0], parts[1], parts[2]
            for file in files:
                file_bytes = await file.read()
                binary_data = io.BytesIO(file_bytes)
                path = f"/Volumes/{catalog}/{schema}/{volume_name}/{file.filename}"
                w.files.upload(path, binary_data, overwrite=True)
                self.uploaded_files.append(file.filename)
                yield rx.toast(f"Uploaded {file.filename} to {path}", level="success")
        except Exception as e:
            yield rx.toast(f"Upload failed: {e}", level="error")
        finally:
            self.is_uploading = False

Resources​

Permissions​

Your app service principal needs the following permissions:

  • USE CATALOG on the catalog of the volume
  • USE SCHEMA on the schema of the volume
  • READ VOLUME and WRITE VOLUME on the volume

See Privileges required for volume operations for more information.

If you declare volume access in a Databricks Asset Bundle, resources.apps[*].resources[*].uc_securable may not grant USE_CATALOG and USE_SCHEMA on the parent catalog and schema (the app still needs them at runtime). As a temporary workaround until bundles can declare those parent grants, add the privileges manually, or see apps_grants_sync: an example Databricks App and Asset Bundle that wires experimental.scripts.postdeploy so parent privileges are applied after each databricks bundle deploy (copy its tools/ into your bundle or mirror the same pattern in databricks.yml).

Dependencies​

requirements.txt
databricks-sdk
reflex