I have an application that's been running since 2015. It both reads and writes to approx 16 calendars via a service account, using the Google node.js library (calendar v3 API). We also have G Suite for Education.
The general process is:
- Every 30 seconds it caches all calendar data via a list operation
- Periodically a student will request an appointment "slot", it first checks to see if the slot is still open (via a list call) then an insert.
That's all it does. It's been running fine until the past few days, where API insert
calls started failing:
{
"code": 403,
"errors": [{
"domain": "usageLimits",
"reason": "quotaExceeded",
"message": "Calendar usage limits exceeded."
}]
}
This isn't all that special - the documentation has three "solutions":
- Read more on the Calendar usage limits in the G Suite Administrator help.
- If one user is making a lot of requests on behalf of many users of a G Suite domain, consider using a Service Account with authority delegation (setting the quotaUser parameter).
- Use exponential backoff.
- I'm not exceeding any of the stated limits as far as I can tell.
- While I'm using a service account, it isn't making a request on behalf of a user. The service account has write access to the calendar and adds the user as an attendee
- Finally, I do not think exponential backoff will help, although I do not have this implemented. The time between a request to insert and the next insert call is measured in seconds, not milliseconds. Additionally, just running calls directly on the command line with a simple script produce the same problem.
Some stats:
2015 - 2,466 inserts, 186 errors
2016 - 25,747 inserts, 237 errors
2017 - 42,815 inserts, 225 errors
2018 - 41,390 inserts, 1,074 errors (990 of which are in the past 3 days)
I have updated the code over the years, but it has remained largely untouched this term.
At this point I'm unsure what to do - there is no channel to reach Google, and while I have not implemented a backoff strategy, the way timings work with this application, subsequent calls are delayed by seconds, and processed in a queue that sequentially processes requests. The only concurrent requests would be list operations.