Weird DNS/connectivity errors when using topgrade

[KizzyCode]

What did you expect to happen?

Topgrade or it's child processes successfully connect to a remote address.

What actually happened?

I have spurious errors that a topgrade child process fails to connect.

This sometimes happens with

• SSH:

  Connecting to HOST...
  ssh: connect to host HOST port 22: Network is unreachable
  

  – even if I'm currently connected to HOST and actively transferring some data to said host.
• Docker:

  Error response from daemon: Get "https://ghcr.io/v2/": dial tcp: lookup ghcr.io on [::1]:53: read udp [::1]:36276->[::1]:53: read: connection refused
  

• zypper (no specific error at hand, but also some kind of cannot find/connect to server)

(If I retry the step a second time, it usually works.)

Additional Details

At first I was pretty sure that this is an issue on my side, however it also happens on other systems (e.g. my server which is in a remote data center with high-reliablity network connection and tight network monitoring). So I started looking at the logs, but found nothing. Additionally, I setup some monitoring on my local machine, and again nothing.

The weird thing is: This only happens with topgrade. I literally have weeks where everything else works flawlessly without network errors etc, and then there is topgrade which reliably fails every two days.

And to be honest im quite a bit puzzled – I'm not sure if it's even reasonably possible for topgrade to introduce weird network errors for child processes; so I'm not sure if this is even related to topgrade – however, this is the only context where such errors occur 🤷🏻‍♀️

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• Which operating system or Linux distribution are you using?
  • This happens with macOS Monterey, macOS Ventura and openSUSE Tumbleweed
• How did you install Topgrade?
  • With HomeBrew on macOS and rust-cargo on openSUSE
• Which version are you running?
  • Topgrade 9.0.1 on both OS