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Overview

Amundsen's data preview feature requires that developers create a custom implementation of base_preview_client for requesting that data. This feature assists with data discovery by providing the end user the option to view a sample of the actual resource data so that they can verify whether or not they want to transition into exploring that data, or continue their search.

Apache Superset is an open-source business intelligence tool that can be used for data exploration. Amundsen's data preview feature was created with Superset in mind, and it is what we leverage internally at Lyft to support the feature. This document provides some insight into how to configure Amundsen's frontend application to leverage Superset for data previews.

Implementation

Implement the base_superset_preview_client to make a request to an instance of Superset.

Shared Logic

base_superset_preview_client implements get_preview_data() of base_preview_client with the minimal logic for this use case.

It updates the headers for the request if optionalHeaders are passed in get_preview_data()

# Clone headers so that it does not mutate instance's state
headers = dict(self.headers)

# Merge optionalHeaders into headers
if optionalHeaders is not None:
    headers.update(optionalHeaders)

It verifies the shape of the data before returning it to the application. If the data does not match the PreviewDataSchema, the request will fail.

# Verify and return the results
response_dict = response.json()
columns = [ColumnItem(c['name'], c['type']) for c in response_dict['columns']]
preview_data = PreviewData(columns, response_dict['data'])
data, errors = PreviewDataSchema().dump(preview_data)
if not errors:
    payload = jsonify({'preview_data': data})
    return make_response(payload, response.status_code)
else:
    return make_response(jsonify({'preview_data': {}}), HTTPStatus.INTERNAL_SERVER_ERROR)

Custom Logic

base_superset_preview_client has an abstract method post_to_sql_json(). This method will contain whatever custom logic is needed to make a successful request to the sql_json enpoint based on the protections you have configured on this endpoint on your instance of Superset. For example, this may be where you have to append other values to the headers, or generate SQL queries based on your use case.

See the following example_superset_preview_client for an example implementation of base_superset_preview_client and post_to_sql_json(). This example assumes a local instance of Superset running on port 8088 with no security, authentication, or authorization configured on the endpoint.

Usage

Under the [preview_client] group, point the table_preview_client_class entry point in your local setup.py to your custom class.

entry_points="""
    ...

    [preview_client]
    table_preview_client_class = amundsen_application.base.examples.example_superset_preview_client:SupersetPreviewClient
"""

Run python3 setup.py install in your virtual environment and restart the application for the entry point changes to take effect