Logging/stdout issue

Questions / Help
1

Hi! I have been having logging issues where the output of my program was missing from the web dashboard and fly logs. I first thought there was another issue with my app but I was able to create a simple image reproducing the problem.

The executable Swift code consists of the following:

import Glibc

var total = ""

while true {
    total += "\(total.count) "
    print(total)
    sleep(3)
}

I rarely see the output in the logs. Sometimes it seems that the output appears at the moment the instance is shutdown.

I tried redirecting the output to a file:

CMD release/FlyLogsTest >> /tmp/output.txt

But I still see erratic behavior: it seems the file isn’t always filled instantly, and once it is, it sometimes gets truncated.

This is Swift code running on base ubuntu:focal image, I also published a deployable repo that exhibits the issue when redirecting the standard output to a file.

This is a very puzzling issue: I never had issues logging anything on Fly nor did I ever have any issues printing anything with Swift.

Would someone have an idea of what might be causing this?

Thank you

2

This is actually an issue related to Swift where stdout doesn’t seem to get flushed, closing this thread.

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