Setup a Google Developers Account
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Use or Create an API Key For Sheets at Developer Console
For Your Google Sheet (If not OAuth, You Need to Make it Visible via URL)
Or you will face PERMISSION_DENIED
Enable Google Sheets API
https://console.developers.google.com/apis/api/sheets.googleapis.com/overview?project=YOURPROJECTID
View Metrics
https://console.developers.google.com/apis/api/sheets.googleapis.com/overview?project=YOURPROJECTISCOOL
Access The Data Via NIFI
https://sheets.googleapis.com/v4/spreadsheets/YOURGOOGLESHEET?includeGridData=true&key=YOURKEY
References:
https://community.cloudera.com/t5/Community-Articles/Streaming-Ingest-of-Google-Sheets-with-HDF-2-0/ta-p/247764
