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Prefect Integration

DataHub supports integration of

  • Prefect flow and task metadata
  • Flow run and Task run information as well as
  • Lineage information when present

What is Prefect Datahub Block?​

Blocks are primitive within Prefect that enable the storage of configuration and provide an interface for interacting with external systems. We integrated prefect-datahub block which use Datahub Rest emitter to emit metadata events while running prefect flow.

Prerequisites to use Prefect Datahub Block​

  1. You need to use either Prefect Cloud (recommended) or the self hosted Prefect server.
  2. Refer Cloud Quickstart to setup Prefect Cloud.
  3. Refer Host Prefect server to setup self hosted Prefect server.
  4. Make sure the Prefect api url is set correctly. You can check it by running below command:
prefect profile inspect
  1. If you are using Prefect Cloud, the API URL should be set as https://api.prefect.cloud/api/accounts/<account_id>/workspaces/<workspace_id>.
  2. If you are using a self-hosted Prefect server, the API URL should be set as http://<host>:<port>/api.

Setup​

For setup details please refer prefect-datahub.

How to validate saved block and emit of metadata​

  1. Go and check in Prefect UI at the Blocks menu if you can see the datahub emitter.
  2. Run a Prefect workflow. In the flow logs, you should see Datahub related log messages like:
Emitting flow to datahub...
Emitting tasks to datahub...

Debugging​

Incorrect Prefect API URL​

If your Prefect API URL aren't being generated correctly or set incorrectly, then in that case you can set the Prefect API URL manually as show below:

prefect config set PREFECT_API_URL='http://127.0.0.1:4200/api'

Connection error for Datahub Rest URL​

If you get ConnectionError: HTTPConnectionPool(host='localhost', port=8080), then in that case your GMS service is not up.