add network_route collector

[kamijin-fanta]

The routing table is an important monitoring metric when operating Linux as a router. The routing table actually set by BGP, OSPF, etc. is useful for troubleshooting.

reference issue #1639

example outputs

# HELP node_network_route network routing table
# TYPE node_network_route gauge
node_network_route{dest="10.0.0.0/24",gw="100.0.0.1",if="eth1",priority="20",proto="zebra",src="",weight="1"} 1
node_network_route{dest="10.0.0.0/24",gw="100.0.0.2",if="eth1",priority="20",proto="zebra",src="",weight="1"} 1
node_network_route{dest="100.0.0.0/24",gw="",if="eth1",priority="0",proto="kernel",src="100.0.0.3",weight=""} 1
node_network_route{dest="192.168.10.0/24",gw="",if="eth0",priority="0",proto="kernel",src="192.168.10.2",weight=""} 1
node_network_route{dest="default",gw="192.168.10.1",if="eth0",priority="0",proto="static",src="",weight=""} 1
# HELP node_network_routes_total network routing table
# TYPE node_network_routes_total gauge
node_network_routes_total{if="eth0"} 2
node_network_routes_total{if="eth1"} 3

[roidelapluie]

thanks for working on this.

does it work with multiple routing tables?

[kamijin-fanta]

@roidelapluie Thanks for your comment. Currently only the main table is referenced. Should I include a custom routing table?

[kamijin-fanta]

What is the status this PR? Need some fixes?

[discordianfish]

Haven't gotten time to review this in details but two things already:

• We're using https://github.com/mdlayher/netlink already, could that be used instead of github.com/vishvananda/netlink?
• Can you add some tests? Probably not as easy as with all the proc fixtures but would be great to have

[kamijin-fanta]

@discordianfish Thank you for the review!

The github.com/jsimonetti/rtnetlink package doesn't seem to support the RTA_MULTIPATH attribute. Multipath is commonly used in routing daemons and I would like to support it.

https://github.com/jsimonetti/rtnetlink/blob/d699427278d3e451dcba83b009ac5a5e84d1d621/route.go#L183-L222

This exporter does not parse files etc. Which part of the test do you think would be better?

[discordianfish]

@mdlayher Are you still maintaining your netlink package? And could we add RTA_MULTIPATH support? I'm going to assume you built the package in a testable way :)

[erolg]

Hi everyone, as a node exporter user I am waiting this feature. Is there any update?

[kamijin-fanta]

I will fix it if I need to change code.

[discordianfish]

Seems like @mdlayher's netlink package isn't very active anymore.. So I'd say we can merge this and rather replace our current use of netlink by vishvananda's package as well. @SuperQ wdyt?

[mdlayher]

"Isn't very active" != "not maintained", my netlink package is widely used and it's effectively complete.

Netlink is not route netlink, and the mentioned "netlink" package conflates the two (among many other things) and adds an iproute2-like API. The equivalent layer in my ecosystem is https://github.com/jsimonetti/rtnetlink. I recently added RTA_MULTIPATH support.

[discordianfish]

@mdlayher Thanks for clarifying! In that case I'd prefer keeping to use your netlink package.

@kamijin-fanta Can you update this PR to use https://github.com/jsimonetti/rtnetlink now that there is RTA_MULTIPATH support?

[kamijin-fanta]

Thanks for the library update. and I rewrote PR to use it.

[erolg]

LGTM. @discordianfish Did you have time to review ?

[discordianfish]

I'd still like to have tests ideally.. We can merge if that's really not possible but somebody should look into that first.

[kamijin-fanta]

I tried to mock the rtnetlink connection, but I couldn't do this because the function field interface is private.

https://github.com/jsimonetti/rtnetlink/blob/master/conn.go

[discordianfish]

Well, I'd say let's merge it as is for now then.

[SuperQ]

I'm going to merge this and fix the go.sum separately.