Can I prolong the lifespan of a Gmail access token?

Other Questions Gmail
1

I’m working on an add-on that needs to grab files from Drive or Gmail attachments and send them to my backend for scanning. While Drive works great, I’m hitting a snag with Gmail access tokens.

The token comes through an event trigger, and I can use it initially. But if the add-on stays open for a while, I get an ‘Access denied: Expired access token’ error when trying to fetch attachments.

Is there a way to refresh or extend the Gmail access token’s lifetime? I’ve looked into the OAuth2 library for Google Apps Script, but the docs say the token isn’t returned for Gmail.

Here’s a snippet of how I’m trying to get the attachments:

function fetchEmailAttachments() {
  GmailApp.setCurrentMessageAccessToken(getCurrentToken());
  const email = GmailApp.getMessageById(getCurrentMessageId());
  const files = email.getAttachments();

  const validDocs = files.filter(file => {
    const fileType = getFileExtension(file.getName());
    return isValidDocumentType(fileType);
  });

  if (validDocs.length === 0) {
    throw new Error('No valid documents found');
  }
  return files;
}

Any ideas on how to keep the token valid longer? Or is there a setting in Google Cloud to extend its lifespan?

2

hey there, i’ve had similar issues. unfortunately, gmail tokens are short-lived by design. instead of trying to extend them, you might wanna consider refreshing the token when it expires. you could catch the ‘Access denied’ error and trigger a token refresh using the oauth2 library. hope this helps!

3

I’ve encountered this issue in my projects as well. Gmail access tokens are indeed short-lived for security reasons. Instead of trying to prolong the token’s lifespan, a more robust approach is to implement a token refresh mechanism.

When you receive the ‘Access denied: Expired access token’ error, you can use the OAuth2 library to request a new token. This approach ensures continuous access without compromising security.

Alternatively, consider using the Gmail API directly instead of GmailApp. The API allows for more granular control over authentication and provides methods for token refresh. It might require more setup initially, but it offers better long-term reliability for your add-on.

4

Having worked on similar projects, I can tell you that prolonging Gmail access tokens isn’t really feasible. Google intentionally keeps them short-lived for security reasons. What’s worked well for me is implementing a token refresh mechanism.

Instead of trying to extend the token’s lifespan, set up error handling in your code. When you catch that ‘Access denied’ error, trigger a token refresh using the OAuth2 library. This way, your add-on can seamlessly obtain a new token without user intervention.

Also, consider caching attachments temporarily on your backend if possible. This can reduce the frequency of token refreshes needed, especially if users are working with the same files repeatedly. Just be mindful of storage limits and implement proper cleanup procedures.

Lastly, if you’re open to refactoring, switching to the Gmail API might give you more flexibility in handling authentication and token management compared to GmailApp.