Adding allowed_device flag for diskstats Collector

[rushilenekar20]

Hey ,
I am suggesting a flag for diskstats collector named as --collector.diskstats.allowed-devices=""

Problem : Requirement for only allowed-devices flag in diskstats collector.

Description :
There is " ignored-devices " flag for diskstats collector which ignores stats of devices .

But in our organisation we faced a problem where Operating System create some devices at runtime whose names are unknown to us . So we were unable to ignored those devices .

As negetive lookahead is not supported in Go language because it conflicts with the O(n)-time guarantees of the library.so, we were unable to ignored those devices.

I suggest to have a flag for only allowed-devices for diskstats collector .

Here are some screenshots of the solution for this problem

1. without using allowed-device flag
   

there are multiple device sda , dm , sr0 .Lets assume sda and sr0 devices were unknown to us and they are created at runtime and we dont want to show metrics of those devices . we only want to show metrics for dm devices.

2)allowed-device flag

3. Use case
   

only dm devices are allowed

[discordianfish]

Makes sense but what about renaming the netdev filter to devFilter or something and use it here as well? https://github.com/prometheus/node_exporter/blob/master/collector/netdev_filter.go

[rushilenekar20]

Makes sense but what about renaming the netdev filter to devFilter or something and use it here as well? https://github.com/prometheus/node_exporter/blob/master/collector/netdev_filter.go

I have commited one change . I tried to solve this current problem using netdev_filter.go . By renaming of netdev_filter to devFilter , i don't know what will be the consequences to another collector which are using netdev filter .

[discordianfish]

Let's get this consistent with the netdev flags. So similar like there, we should:

1. rename this to device-include
2. add new flag device-exclude
3. Prefix the description of collector.diskstats.ignored-devices with "DEPRECATED: Use collector.diskstats.device-exclude" and add .Hidden() before String()
4. Support excluding by setting either device-exclude but warn if people use the now deprecated flag

Basically: https://github.com/prometheus/node_exporter/blob/master/collector/netdev_common.go#L33-L77

[discordianfish]

Makes sense but what about renaming the netdev filter to devFilter or something and use it here as well? https://github.com/prometheus/node_exporter/blob/master/collector/netdev_filter.go

I have commited one change . I tried to solve this current problem using netdev_filter.go . By renaming of netdev_filter to devFilter , i don't know what will be the consequences to another collector which are using netdev filter .

Yeah you need to rename it in the other collectors but that should be straight forward.

[discordianfish]

LGTM, thanks!

[rushilenekar20]

Hey @SuperQ , We need this flag . Could you help me for this PR ?

[SuperQ]

Looks like this needs a rebase.

[SuperQ]

Also the tests are failing:

collector/diskstats_linux_test.go:52:3: undefined: ignoredDevices

[SuperQ]

I split out the netDevFilter out into a separate PR to simplify this change.

#2378

[SuperQ]

It looks like you've incorrectly rebased your branch, bringing in additional unrelated commits. Please fix up your commit history.

[SuperQ]

I've merged #2378, please rebase and fix up the commit history on this change.

[SuperQ]

I've merged #2378, please rebase and fix up the commit history on this change.

[rushilenekar20]

Hey @SuperQ @discordianfish , I have tried a lot to rebase and fix commit history of this branch but i failed to do so after following right steps.
Now we can two things
1)u can guide me how to rebase and fix commits on this branch .
2) I have done all this changes on my new branch called rushilenekar20/diskstatsFlag
which works fine and we can merge it easily . I can create new PR with that branch

what should we do ?

[SuperQ]

Closing in favor of #2417