How to host and share Data Docs on GCS

This guide will explain how to host and share Data Docs on Google Cloud Storage. We recommend using IP-based access, which is achieved by deploying a simple Google App Engine app. Data Docs can also be served on Google Cloud Storage if the contents of the bucket are set to be publicly readable, but this is strongly discouraged.

Prerequisites: This how-to guide assumes you have already:

Steps

  1. Create a Google Cloud Storage bucket using gsutil.

Make sure you modify the project name, bucket name, and region for your situation.

> gsutil mb -p my_org_project -l US-EAST1 -b on gs://my_org_data_docs/
Creating gs://my_org_data_docs/...
  1. Create a directory for your Google App Engine app and add the following files.

We recommend placing it in your project directory, for example great_expectations/team_gcs_app.
app.yaml (make sure to use your own bucket name)
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runtime: python37
env_variables:
    CLOUD_STORAGE_BUCKET: my_org_data_docs
requirements.txt
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flask>=1.1.0
google-cloud-storage
main.py
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import logging
import os
from flask import Flask, request
from google.cloud import storage
app = Flask(__name__)
# Configure this environment variable via app.yaml
CLOUD_STORAGE_BUCKET = os.environ['CLOUD_STORAGE_BUCKET']
@app.route('/', defaults={'path': 'index.html'})
@app.route('/<path:path>')
def index(path):
    gcs = storage.Client()
    bucket = gcs.get_bucket(CLOUD_STORAGE_BUCKET)
    try:
        blob = bucket.get_blob(path)
        content = blob.download_as_string()
        if blob.content_encoding:
            resource = content.decode(blob.content_encoding)
        else:
            resource = content
    except Exception as e:
        logging.exception("couldn't get blob")
        resource = "<p></p>"
    return resource
@app.errorhandler(500)
def server_error(e):
    logging.exception('An error occurred during a request.')
    return """
    An internal error occurred: <pre>{}</pre>
    See logs for full stacktrace.
    """.format(e), 500
  1. If you haven’t done so already, authenticate the gcloud CLI and set the project.

Insert the appropriate project name.
> gcloud auth login && gcloud config set project <<project_name>>
  1. Deploy your Google App Engine app.

Issue the following CLI command from within the app directory created above: gcloud app deploy.

  1. Set up Google App Engine firewall for your app to control access.

Visit the following page for instructions on creating firewall rules: Creating firewall rules

  1. Add a new GCS site to the data_docs_sites section of your great_expectations.yml.

You may also replace the default local_site if you would only like to maintain a single GCS Data Docs site.

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data_docs_sites:
  local_site:
    class_name: SiteBuilder
    show_how_to_buttons: true
    store_backend:
      class_name: TupleFilesystemStoreBackend
      base_directory: uncommitted/data_docs/local_site/
    site_index_builder:
      class_name: DefaultSiteIndexBuilder
  gs_site:  # this is a user-selected name - you may select your own
    class_name: SiteBuilder
    store_backend:
      class_name: TupleGCSStoreBackend
      project: my_org_project # UPDATE the project name with your own
      bucket: my_org_data_docs  # UPDATE the bucket name here to match the bucket you configured above
    site_index_builder:
      class_name: DefaultSiteIndexBuilder
  1. Build the GCS Data Docs site.

Use the following CLI command: great_expectations docs build --site-name gs_site. If successful, the CLI will provide the object URL of the index page. Since the bucket is not public, this URL will be inaccessible. Rather, you will access the Data Docs site using the App Engine app configured above.

> great_expectations docs build --site-name gs_site

The following Data Docs sites will be built:

 - gs_site: https://storage.googleapis.com/my_org_data_docs/index.html

Would you like to proceed? [Y/n]: Y

Building Data Docs...

Done building Data Docs
  1. Test that everything was configured properly by launching your App Engine app.

Issue the following CLI command: gcloud app browse. If successful, the gcloud CLI will provide the URL to your app and launch it in a new browser window. The page displayed should be the index page of your Data Docs site.

Additional notes

  • If you wish to host a Data Docs site through a private DNS, you can configure a base_public_path for the Data Docs Store. The following example will configure a GCS site with the base_public_path set to www.mydns.com. Data Docs will still be written to the configured location on GCS (for example https://storage.cloud.google.com/my_org_data_docs/index.html), but you will be able to access the pages from your DNS (http://www.mydns.com/index.html in our example).

data_docs_sites:
  gs_site:  # this is a user-selected name - you may select your own
    class_name: SiteBuilder
    store_backend:
      class_name: TupleGCSStoreBackend
      project: my_org_project
      bucket: my_org_data_docs
      base_public_path: http://www.mydns.com
    site_index_builder:
      class_name: DefaultSiteIndexBuilder

Additional resources

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