I have two lambda functions in my AWS. One acts as a custom authorizer and the other acts as a notification service which calls the firebase FCM notification service.

When a request is made first time in a day to the notification lambda there is no response. The lambda does not work and hence does not call the firebase service.

It seemed like a cold start problem to me so I added the provisioned concurrency for both auth and notification lambda to 1 in the hope that it will work. But the problem persists.

Cloudwatch logs are of no help at all since nothing gets printed to it which I can use to figure out the issue. Either the authorizer lambda goes cold and does not response or the primary notification lambda goes cold and does not response or even both of them have issues.

After the first call to lambda fails any subsequent calls then work smoothly like a charm.

I do not want to install any plugin which will keep the lambda warm (not an option from the client) so is there some other way I can diagnose this problem and fix it?