Skip to main content

How to configure an Expectation Store to use Azure Blob Storage

By default, newly ProfiledThe act of generating Metrics and candidate Expectations from data. ExpectationsA verifiable assertion about data. are stored as Expectation SuitesA collection of verifiable assertions about data. in JSON format in the expectations/ subdirectory of your great_expectations/ folder. This guide will help you configure Great Expectations to store them in Azure Blob Storage.

Prerequisites: This how-to guide assumes you have:

Steps

1. Configure the config_variables.yml file with your Azure Storage credentials

We recommend that Azure Storage credentials be stored in the config_variables.yml file, which is located in the uncommitted/ folder by default, and is not part of source control. The following lines add Azure Storage credentials under the key AZURE_STORAGE_CONNECTION_STRING. Additional options for configuring the config_variables.yml file or additional environment variables can be found here.

AZURE_STORAGE_CONNECTION_STRING: "DefaultEndpointsProtocol=https;EndpointSuffix=core.windows.net;AccountName=<YOUR-STORAGE-ACCOUNT-NAME>;AccountKey=<YOUR-STORAGE-ACCOUNT-KEY==>"

2. Identify your Data Context Expectations Store

In your great_expectations.yml , look for the following lines. The configuration tells Great Expectations to look for Expectations in a StoreA connector to store and retrieve information about metadata in Great Expectations. called expectations_store. The base_directory for expectations_store is set to expectations/ by default.

expectations_store_name: expectations_store

stores:
expectations_store:
class_name: ExpectationsStore
store_backend:
class_name: TupleFilesystemStoreBackend
base_directory: expectations/

3. Update your configuration file to include a new Store for Expectations on Azure Storage account

In our case, the name is set to expectations_AZ_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 TupleAzureBlobStoreBackend, container will be set to the name of your blob container (the equivalent of S3 bucket for Azure) you wish to store your expectations, prefix will be set to the folder in the container where Expectation files will be located, and connection_string will be set to ${AZURE_STORAGE_CONNECTION_STRING}, which references the corresponding key in the config_variables.yml file.

expectations_store_name: expectations_AZ_store

stores:
expectations_AZ_store:
class_name: ExpectationsStore
store_backend:
class_name: TupleAzureBlobStoreBackend
container: <blob-container>
prefix: expectations
connection_string: ${AZURE_STORAGE_CONNECTION_STRING}
note

If the container is called $web (for hosting and sharing Data Docs on Azure Blob Storage) then set container: \$web so the escape char will allow us to reach the $webcontainer.

note

Various authentication and configuration options are available as documented in hosting and sharing Data Docs on Azure Blob Storage.

4. Copy existing Expectation JSON files to the Azure blob (This step is optional)

One way to copy Expectations into Azure Blob Storage is by using the az storage blob upload command, which is part of the Azure SDK. The following example will copy one Expectation, exp1 from a local folder to the Azure blob. Information on other ways to copy Expectation JSON files, like the Azure Storage browser in the Azure Portal, can be found in the Documentation for Azure.

export AZURE_STORAGE_CONNECTION_STRING="DefaultEndpointsProtocol=https;EndpointSuffix=core.windows.net;AccountName=<YOUR-STORAGE-ACCOUNT-NAME>;AccountKey=<YOUR-STORAGE-ACCOUNT-KEY==>"
az storage blob upload -f <local/path/to/expectation.json> -c <GREAT-EXPECTATION-DEDICATED-AZURE-BLOB-CONTAINER-NAME> -n <PREFIX>/<expectation.json>
example :
az storage blob upload -f great_expectations/expectations/exp1.json -c <blob-container> -n expectations/exp1.json

Finished[#############################################################] 100.0000%
{
"etag": "\"0x8D8E08E5DA47F84\"",
"lastModified": "2021-03-06T10:55:33+00:00"
}

5. Confirm that the new Expectations Store has been added by running great_expectations store list

Notice the output contains two Expectation StoresA connector to store and retrieve information about collections of verifiable assertions about data.: the original expectations_store on the local filesystem and the expectations_AZ_store we just configured. This is ok, since Great Expectations will look for Expectations in Azure Blob as long as we set the expectations_store_name variable to expectations_AZ_store, which we did in the previous step. The config for expectations_store can be removed if you would like.

great_expectations store list

- name: expectations_store
class_name: ExpectationsStore
store_backend:
class_name: TupleFilesystemStoreBackend
base_directory: expectations/

- name: expectations_AZ_store
class_name: ExpectationsStore
store_backend:
class_name: TupleAzureBlobStoreBackend
connection_string: DefaultEndpointsProtocol=https;EndpointSuffix=core.windows.net;AccountName=<YOUR-STORAGE-ACCOUNT-NAME>;AccountKey=<YOUR-STORAGE-ACCOUNT-KEY==>
container: <blob-container>
prefix: expectations

6. Confirm that Expectations can be accessed from Azure Blob Storage by running great_expectations suite list

If you followed Step 4, the output should include the Expectation we copied to Azure Blob: exp1. If you did not copy Expectations to the new Store, you will see a message saying no Expectations were found.

great_expectations suite list

Using v2 (Batch Kwargs) API
1 Expectation Suite found:
- exp1