mcejp/sheetkeeper

Sheetkeeper -- automated Google Sheets maintenance

Go to https://console.cloud.google.com/projectcreate and create a project
Go to https://console.cloud.google.com/apis/api/sheets.googleapis.com and enable Google Sheets API for the newly created project
On the top you should see the message To use this API, you may need credentials. Click 'CREATE CREDENTIALS' to get started. Click the blue button to the right.
Select Application data, No, and click Next.

Choose an arbitrary Service account ID (sheetkeeper will do), click Next
Click Continue and Done
Go to the Credentials panel (on the left) and select the newly created Service Account
Go to the Keys tab (on top) and click Add key -> Create new key
Confirm the JSON type and create the key. Download the file that will pop up.
Base64-encode the file with the following command: base64 -w0 <filename>.json. This will be the contents as your SHEETKEEPER_CREDENTIALS variable.

Environment variables:

SHEETKEEPER_CREDENTIALS base64-encoded Service Account credentials (see instructions above)
SHEETKEEPER_SHEETS (format: id1:sheet1:sheet2:sheet3::id2:sheet1; IDs are spreadsheet IDs, sheets are the tab names)

S3 options (used for backup of sheet contents):