I am studying Lambdas of my project and I've seen that one of them is idle. In the top of dashboard page I see block with text:
The function __ is idle. To reactivate your function, choose Restore.
I slightly confused of it because this function is very similar to others which isn't marked as idle but as well haven't been launched for couple of months. Since I haven't find answers in AWS documentation i'd appreciate somebody to explain me what difference between functions in idle state and not, and how/why function becomes Idle?
It is related to VPC, please check this doc.
If your functions aren't active for a long period of time, Lambda reclaims its network interfaces, and the functions become Idle. To reactivate an idle function, invoke it. This invocation fails, and the function enters a Pending state again until a network interface is available.
https://docs.aws.amazon.com/lambda/latest/dg/configuration-vpc.html