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How to configure a Validation Result store in GCS

By default, Validations are stored in JSON format in the uncommitted/validations/ subdirectory of your great_expectations/ folder. Since Validations may include examples of data (which could be sensitive or regulated) they should not be committed to a source control system. This guide will help you configure a new storage location for Validations in a Google Cloud Storage (GCS) bucket.

Prerequisites: This how-to guide assumes you have:
  • Completed the Getting Started Tutorial
  • Have a working installation of Great Expectations
  • Configured a Data Context.
  • Configured an Expectations Suite.
  • Configured a Checkpoint.
  • Configured a Google Cloud Platform (GCP) service account with credentials that can access the appropriate GCP resources, which include Storage Objects.
  • Identified the GCP project, GCS bucket, and prefix where Validations will be stored.

Steps#

  1. Configure your GCP credentials

    Check that your environment is configured with the appropriate authentication credentials needed to connect to the GCS bucket where Validations will be stored.

    The Google Cloud Platform documentation describes how to verify your authentication for the Google Cloud API, which includes:

    1. Creating a Google Cloud Platform (GCP) service account,
    2. Setting the GOOGLE_APPLICATION_CREDENTIALS environment variable,
    3. Verifying authentication by running a simple Google Cloud Storage client library script.
  2. Identify your Data Context Validations Store

    In your great_expectations.yml, look for the following lines. The configuration tells Great Expectations to look for Validations in a store called validations_store. The base_directory for validations_store is set to uncommitted/validations/ by default.

    validations_store_name: validations_store
    stores:    validations_store:        class_name: ValidationsStore        store_backend:            class_name: TupleFilesystemStoreBackend            base_directory: uncommitted/validations/
  1. Update your configuration file to include a new store for Validations on GCS

    In our case, the name is set to validations_GCS_store, but it can be any name you like. We also need to make some changes to the store_backend settings. The class_name will be set to TupleGCSStoreBackend, project will be set to your GCP project, bucket will be set to the address of your GCS bucket, and prefix will be set to the folder on GCS where Validation files will be located.

    validations_store_name: validations_GCS_storestores:    validations_GCS_store:        class_name: ValidationsStore        store_backend:            class_name: TupleGCSStoreBackend            project: '<your_GCP_project_name>'            bucket: '<your_GCS_bucket_name>'            prefix: '<your_GCS_folder_name>'
warning

If you are also storing Expectations in GCS or DataDocs in GCS, please ensure that the prefix values are disjoint and one is not a substring of the other.

  1. Copy existing Validation results to the GCS bucket. (This step is optional).

    One way to copy Validations into GCS is by using the gsutil cp command, which is part of the Google Cloud SDK. In the example below, two Validation results, Validation1 and Validation2 are copied to the GCS bucket. Information on other ways to copy Validation results, like the Cloud Storage browser in the Google Cloud Console, can be found in the Documentation for Google Cloud.

    gsutil cp uncommitted/validations/Validation1.json gs://'<your_GCS_bucket_name>'/'<your_GCS_folder_name>'gsutil cp uncommitted/validations/Validation2.json gs://'<your_GCS_bucket_name>'/'<your_GCS_folder_name>'
    Operation completed over 2 objects/58.8 KiB.
  1. Confirm that the new Validations store has been added by running great_expectations --v3-api store list.

    Notice the output contains two Validation stores: the original validations_store on the local filesystem and the validations_GCS_store we just configured. This is ok, since Great Expectations will look for Validations in GCS as long as we set the validations_store_name variable to validations_GCS_store, and the config for validations_store can be removed if you would like.

    great_expectations --v3-api store list
    - name: validations_storeclass_name: ValidationsStorestore_backend:    class_name: TupleFilesystemStoreBackend    base_directory: uncommitted/validations/
    - name: validations_GCS_storeclass_name: ValidationsStorestore_backend:    class_name: TupleGCSStoreBackend    project: '<your_GCP_project_name>'    bucket: '<your_GCS_bucket_name>'    prefix: '<your_GCS_folder_name>'
  2. Confirm that the Validations store has been correctly configured.

    Run a Checkpoint to store results in the new Validations store on GCS then visualize the results by re-building Data Docs.

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