bug#40125: Problem with guix offload: Remote channel closed

[Mikael Djurfeldt]

I did this.

What is a bit strange is that the error message seemingly randomly alters between what I already reported above and the following:

mdj@hat:~/prusa$ guix offload test
guix offload: testing 1 build machines defined in '/etc/guix/machines.scm'...
guix offload: Guix is usable on 'wand.pdc.kth.se' (test returned "/gnu/store/883yjkl46dxw9mzykykmbs0yzwyxm17z-test")
guix offload: 'wand.pdc.kth.se' is running GNU Guile 3.0.1
sending 1 store item (0 MiB) to 'wand.pdc.kth.se'...
exporting path `/gnu/store/kw12ny565xl5p05ag6ysgshc9mhh4rz2-export-test'
guix offload: error: unknown error while sending files over SSH

This error message is more common. In this case, I couldn't see anything obviously strange except the following backtrace which contains strange characters:

31963 write(2, "Backtrace:\n          13 (apply-smob/1 #<catch-closure 56464c2232a0>)\nIn ice-9/boot-9.scm:\n    718:2 12 (call-with-prompt (\"prompt\") #<procedure 56464c2407e0 \342\200\246> \342\200\246)\nIn ice-9/eval.scm:\n    619:8 11 (_ #(#(#<directory (guile-user) 56464c2c4750>)))\nIn ice-9/command-line.scm:\n   181:18 10 (_ #<input: string 56464c2d2bd0>)\nIn unknown file:\n           9 (eval (begin (use-modules (guix) (srfi srfi-34) # #) \342\200\246) #)\nIn ice-9/eval.scm:\n   721:20  8 (primitive-eval (begin (use-modules (guix) (srfi \342\200\246) \342"..., 1150 <unfinished ...>

I have also noticed that the above (the error message) happens inside the function send-files. It is the last error clause at the end of the function which reports the error message.

I'd like to be able to, e.g., modify the function send-files to give some debugging output. How can I easily do that? Should I checkout guix with git and try to run it in the source tree? Or do you have other suggestions?

Best regards,

Mikael

On Sat, Mar 21, 2020 at 11:16 PM Ludovic Courtès <address@hidden> wrote:

Hi Mikael,

Mikael Djurfeldt <address@hidden> skribis:

> I will look at the other buh reports. Meanwhile, do you have any hint on
> where to look/insert logging code in order to see what is going on?

On ‘wand’, can you run something like:

  sudo strace -s 500 -p $(pidof sshd) -f -o sshd.log

After that, run ‘guix offload test’ from the other host, and check what
‘sshd.log’ contains.  If would in particular look for all the ‘execve’
syscalls as well as what happens right before ‘exit_group’ syscalls.
There are probably error messages lurking there.  :-)

You can share excerpts of the log but note that it will contain
sensitive crypto material, so beware.

Thanks in advance,
Ludo’.