Monitoring cloud functions - exclude irrelevant errors

[antonff]

I want to create an alert when the success rate for my cloud function falls below certain threshold. I created an alert policy that checks the ratio of successful requests (status=ok) to all requests. The MQL query looks like this:

fetch cloud_function
| metric 'cloudfunctions.googleapis.com/function/execution_count'
| filter resource.function_name == 'my-function'
| { t_0:
filter metric.status == 'ok'
| align delta()
| group_by [resource.function_name],
[value_execution_count_aggregate: aggregate(value.execution_count)]
; t_1:
ident
| align delta()
| group_by [resource.function_name],
[value_execution_count_aggregate: aggregate(value.execution_count)] }
| ratio
| window 60m
| condition ratio < 0.99 '1'

It works fine for the most part, but there's a problem. My users can send invalid requests to the function, e.g. use HTTP GET instead of POST, and the function will fail with status=error. If these errors happen often, they trigger my alarm. But it's undesirable since it's not something I can fix or control.

Is there a way to exclude  specific errors from Cloud Function metrics? Or is there a better way to monitor success rate for a Cloud Function?

[robertcarlos]

Hi @antonff,

Welcome to Google Cloud Community!

As of the moment, here are the documentations that contains all the operations (so far) that may be helpful for your MQL queries:

• Sample MQL queries 
• Monitoring Query Language reference 

You could also check Cloud Monitoring overview as you may also find this helpful.

I also suggest filing a feature request so that our engineers could take a look at this. We don't have a specific ETA on this but you can keep track of its progress once the ticket has been created.

Hope this helps.