Differentiate the error type in metrics for filesystem collecter

[PamelaMei-SAP]

Since node_exporter can capture the error of mountpoint time out, is it OK to report such error as different value in node_filesystem_device_error metrics e.g. 255 other than 1, since some permission error has the same value as 1
node_filesystem_device_error{device="...",fstype="nfs4",mountpoint="/test_nfs"} 1

Host operating system: output of uname -a

Linux 4.12.14-122.189-default

node_exporter version: output of node_exporter --version

node_exporter, version 1.5.0

node_exporter command line flags

--log.level=debug --collector.systemd --web.listen-address=:9100

node_exporter log output

2024-02-08T10:30:58.944877+00:00 vsa12424973 node_exporter[12644]: ts=2024-02-08T10:30:58.944Z caller=filesystem_linux.go:137 level=debug collector=filesystem msg="Mount point timed out, it is being labeled as stuck and will not be monitored" mountpoint=/test_nfs

Are you running node_exporter in Docker?

NO

What did you do that produced an error?

Not a bug, but expect a new feature
Differentiate value in node_filesystem_device_error metrics

What did you expect to see?

node_filesystem_device_error{device="...",fstype="nfs4",mountpoint="/test_nfs"} 255

What did you see instead?

node_filesystem_device_error{device="...",fstype="nfs4",mountpoint="/test_nfs"} 1

[SuperQ]

I think it's a good idea to surface the error, but we don't typically use the metric value like that. Rather we would add a label to differentiate the error.

So, something like this:

node_filesystem_device_error{device="/dev/foo",fstype="nfs4",mountpoint="/test_nfs",device_error="mountpoint timeout"} 1

[PamelaMei-SAP]

Thank you @SuperQ . I did update locally and tested using your suggested new label. It works well.
So how can I raise my PR for further review? since I have the authentication error when my push commits to my private branch. Can you please help?
git push origin surface_filesystem_device_error_#2918
Username for 'https://github.com': pamela.mei@sap.com
Password for 'https://pamela.mei@sap.com@github.com':
remote: Permission to prometheus/node_exporter.git denied to PamelaMei-SAP.
fatal: unable to access 'https://github.com/prometheus/node_exporter.git/': The requested URL returned error: 403

Scenario-1: No device error
curl http://localhost:9100/metrics | grep node_filesystem_device_error | grep 100.70.222.247
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 83276 0 83276 0 0 1786k 0 --:--:-- --:--:-- --:--:-- 1807k
node_filesystem_device_error{device="100.70.222.247:/share_5618cf05_5d99_44b6_a90d_8c2797929dbb",device_error="",fstype="nfs4",mountpoint="/test_nfs"} 0

Scenario-2: mountpoint timeout
curl http://localhost:9100/metrics | grep node_filesystem_device_error | grep 100.70.222.247
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 83312 0 83312 0 0 3053k 0 --:--:-- --:--:-- --:--:-- 3129k
node_filesystem_device_error{device="100.70.222.247:/share_5618cf05_5d99_44b6_a90d_8c2797929dbb",device_error="mountpoint timeout",fstype="nfs4",mountpoint="/test_nfs"} 1

Scenario-3: error from statfs() e.g. permission denied
curl http://localhost:9100/metrics | grep node_filesystem_device_error | grep 100.70.222.247
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 83208 0 83208 0 0 2943k 0 --:--:-- --:--:-- --:--:-- 3009k
node_filesystem_device_error{device="100.70.222.247:/share_5618cf05_5d99_44b6_a90d_8c2797929dbb",device_error="permission denied",fstype="nfs4",mountpoint="/test_nfs"} 1

[discordianfish]

@PamelaMei-SAP Looks like you're trying to push to our repo. You need to fork our repo, push the changes to your fork and then open a PR: https://docs.github.com/en/get-started/exploring-projects-on-github/contributing-to-a-project

[PamelaMei-SAP]

Thx @discordianfish for this info.
Latest PR is here: #2923
Unfortunately gofmt error took time to fix, because I used go1.22.0 while circleci worker node is using go1.21.7, After I swicthed to go1.21.7 pipeline passed by using gofmt adjustment.
@SuperQ , @discordianfish could you please help review #2923 ?
Thanks for your great effort for help in advance.