improving command error message info

[zhangzhiqiangcs]

When zfs_exporter is used in containers, more error message will help uesr know the container is missing common shared library like zfsutils-linux.

currently, the error message like

ts=2024-01-13T02:59:35.655Z caller=zfs.go:219 level=error msg="Executing collector" status=error collector=dataset-filesystem durationSeconds=0 err="exit status 127"
ts=2024-01-13T02:59:35.655Z caller=zfs.go:219 level=error msg="Executing collector" status=error collector=dataset-snapshot durationSeconds=0 err="exit status 127"
ts=2024-01-13T02:59:35.655Z caller=zfs.go:219 level=error msg="Executing collector" status=error collector=dataset-volume durationSeconds=0 err="exit status 127"
ts=2024-01-13T02:59:35.655Z caller=zfs.go:219 level=error msg="Executing collector" status=error collector=pool durationSeconds=0 err="exit status 127"

after this pr, the error message is like

ts=2024-01-13T02:59:04.950Z caller=zfs.go:219 level=error msg="Executing collector" status=error collector=pool durationSeconds=0 err="Failed to wait command /usr/sbin/zpool list -Ho name, err output: \"zpool: error while loading shared libraries: libzfs.so.4: cannot open shared object file: No such file or directory\n\": exit status 127"
ts=2024-01-13T02:59:04.950Z caller=zfs.go:219 level=error msg="Executing collector" status=error collector=dataset-filesystem durationSeconds=0 err="Failed to wait command /usr/sbin/zpool list -Ho name, err output: \"zpool: error while loading shared libraries: libzfs.so.4: cannot open shared object file: No such file or directory\n\": exit status 127"
ts=2024-01-13T02:59:04.951Z caller=zfs.go:219 level=error msg="Executing collector" status=error collector=dataset-snapshot durationSeconds=0 err="Failed to wait command /usr/sbin/zpool list -Ho name, err output: \"zpool: error while loading shared libraries: libzfs.so.4: cannot open shared object file: No such file or directory\n\": exit status 127"

[pdf]

Thanks for this, couple of minor change requests.

[pdf]

Please also apply these changes to the zfs execution

zfs_exporter/zfs/zfs.go

Line 78 in 30f2d5a

if err = c.Start(); err != nil {

[zhangzhiqiangcs]

Please also apply these changes to the zfs execution

zfs_exporter/zfs/zfs.go

Line 78 in 30f2d5a

if err = c.Start(); err != nil {

@pdf As far as I know, if c.Start() fails，usually means fork/exec error, we can not get the stderr of the command. Please check and let me know If I was wrong

And the error I encountered libzfs.so.4: cannot open shared object file will be catched at cmd.Wait() not cmd.Start()

[zhangzhiqiangcs]

ping @pdf, Could you give some suggestions or merge this

[pdf]

Sorry for the delay, I've been travelling for work.

Please also apply these changes to the zfs execution

zfs_exporter/zfs/zfs.go

Line 78 in 30f2d5a

if err = c.Start(); err != nil {

@pdf As far as I know, if c.Start() fails，usually means fork/exec error, we can not get the stderr of the command. Please check and let me know If I was wrong

And the error I encountered libzfs.so.4: cannot open shared object file will be catched at cmd.Wait() not cmd.Start()

What I meant was, please apply this logic to the call to zfs in that file as you have for the call to zpool in zpool.go

[zhangzhiqiangcs]

I see, just done it @pdf

[pdf]

Thanks for the update, apologies for the delay.