Feature: Include OS release/version metric

[BenB196]

Currently Node Exporter has a metric called: node_uname_info which of course exposes uname info. While this is nice, it does not help if you are running different OSes which could have similar uname info.

Therefore it would be nice to include a similar node_os_release_info metric which would provide information regarding the OS release/version of the node.

This information can be easily gotten from files like:
/etc/release
/etc/os-release
/etc/version

While this functionality could be added through a textfile collector script, I think it would make sense to add it to the base exporter as uname is already supported here.

[pgier]

Some older systems may not include any of those files, although I agree it would be useful to have this information as metrics. Implementing things like this as a built-in collector isn't ideal because it means the same info needs to be re-read for each scrape. But it also would be nice to have a more standard way to collect the info than a textfile collector.

[discordianfish]

Are these files standardized in some form?
Not sure about adding a collector for that though.. But what about a collector that takes a regex to extract metrics from files?
I don't think though that re-reading the file on every scrape is an issue. Not doing would also raise the question what to do on system upgrades where the version might change.

[brian-brazil]

But what about a collector that takes a regex to extract metrics from files?

That sounds like something beyond the scope of the node exporter, as is the majority of what we do is careful parsing of kernel files, rather than being a generic regex metrics extraction tool.

[BenB196]

I am not sure if this will help at all, but outside of using the files. Linux has the lsb_release -a command which will provide the same information in a standardized output. The only issue is that this command is dependency based, and distros like Alpine don't natively come with the package required.

As for the standardization of file, here is what I was able to find out about each of the files listed:

• /etc/os-release - https://www.freedesktop.org/software/systemd/man/os-release.html - This seems to be the standard with most new distro releases

I was unable to find out much about the standardization of /etc/release or /etc/version. However, I did find this post about parsing these types of files. http://linuxmafia.com/faq/Admin/release-files.html

Not sure how well this would implement into the current node_exporter format though.

[discordianfish]

@brian-brazil I'm also not sure that functionality should be part of the node-exporter. But parsing regular files somewhere else isn't either..

[roidelapluie]

I do not think we should parse the file but I am pretty confident that there is a systemd api to get that information.

[SuperQ]

If we can parse /etc/os-release, I don't see this as too terrible. If there is no file, we can just skip it.

For example, https://github.com/acobaugh/osrelease seems reasonably ok.

[BenB196]

Unsure if this helps, but looking at how Elastic gets OS info for their beats. It looks like they also scrape the files.

https://github.com/elastic/go-sysinfo/blob/b973e55d69b7d12962cac1f4e5203fed1750824d/providers/linux/os.go

Also, here is a script I ended up writing (for text file collector) as a work around to my issue until node exporter supports something by default. Not the prettiest, but works:

https://pastebin.com/rxR1t6wP

[discordianfish]

I don't think it's a good idea to parse the file. We also say explicitly in our CONTRIBUTING.md: A Collector may only read /proc or /sys files, use system calls or local sockets to retrieve metrics.

I'm open though to add this to the systemd collector if it's available there.

[dtchanpura]

I agree with the statement. Also these values won't change a lot, so to achieve this, I added this simple textfile collector script executed via cron at reboot updating the value (in case if it changes). Let me know if this serves the purpose, I can check and create a PR on https://github.com/prometheus-community/node-exporter-textfile-collector-scripts for the same.

#!/bin/bash

TEXTFILE_COLLECTOR_PATH=/var/lib/node_exporter/textfile_collector
. /etc/os-release

cat << INFO > ${TEXTFILE_COLLECTOR_PATH}/os-release.prom.xx
# HELP node_os_info A metric with a constant '1' value labeled by id, id_like, name, pretty_name, version, version_codename and version_id
# TYPE node_os_info gauge
INFO
echo "node_os_info{id=\"${ID}\",id_like=\"${ID_LIKE}\",name=\"${NAME}\",pretty_name=\"${PRETTY_NAME}\",version=\"${VERSION}\",version_codename=\"${VERSION_CODENAME}\",version_id=\"${VERSION_ID}\"} 1" >> ${TEXTFILE_COLLECTOR_PATH}/os-release.prom.xx

mv ${TEXTFILE_COLLECTOR_PATH}/os-release.prom.xx ${TEXTFILE_COLLECTOR_PATH}/os-release.prom

[bdrung]

I disagree that the OS release/version metric does not fit into node_exporter:

• The file location and format is standardized: https://www.freedesktop.org/software/systemd/man/os-release.html
• node_exporter parses much more complicated /proc or /sys files