Parse ipv6 addresses in ipvs backend status

[filippog]

We are running ipvs collector from node_exporter on a machine receiving ipv6 traffic too, though node_exporter 0.13 fails with this:

time="2017-04-19T09:47:26Z" level=error msg="ERROR: ipvs collector failed after 0.000758s: could not get backend status: invalid IP: [2620" source="node_exporter.go:91"

And the /proc/net/ip_vs file looks like this (after redacting the addresses)

# cat /proc/net/ip_vs
IP Virtual Server version 1.2.1 (size=1048576)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP  00000000:0050 sh  
  -> 00000000:0050      Route   1      33         10        
  -> 00000000:0050      Route   1      48         52        
  -> 00000000:0050      Route   1      56         92        
  -> 00000000:0050      Route   1      48         15        
  -> 00000000:0050      Route   1      32         52        
  -> 00000000:0050      Route   1      62         28        
  -> 00000000:0050      Route   1      19         30        
  -> 00000000:0050      Route   1      93         43        
TCP  [2620:0000:0000:0000:0000:0000:0000:0000]:01BB sh 
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:01BB      Route   1      0          0         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:01BB      Route   1      2          0         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:01BB      Route   1      2          0         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:01BB      Route   1      0          0         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:01BB      Route   1      2          0         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:01BB      Route   1      1          3         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:01BB      Route   1      1          1         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:01BB      Route   1      1          3         
TCP  00000000:01BB sh  
  -> 00000000:01BB      Route   1      35         59        
  -> 00000000:01BB      Route   1      74         104       
  -> 00000000:01BB      Route   1      275        340       
  -> 00000000:01BB      Route   1      25         56        
  -> 00000000:01BB      Route   1      26         290       
  -> 00000000:01BB      Route   1      36         303       
  -> 00000000:01BB      Route   1      20         326       
  -> 00000000:01BB      Route   1      27         297       
TCP  [2620:0000:0000:0000:0000:0000:0000:0000]:0050 sh 
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:0050      Route   1      0          0         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:0050      Route   1      0          0         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:0050      Route   1      1          1         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:0050      Route   1      0          0         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:0050      Route   1      0          0         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:0050      Route   1      0          2         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:0050      Route   1      0          0         
  -> [2620:0000:0000:0000:0000:0000:0000:0000]:0050      Route   1      0          2         

[SuperQ]

Interesting, what kernel version are you using? The current code parses IPv6 via the same hex format.

[SuperQ]

@matthiasr, where did you find the sample of a /proc/net/ip_vs that contained an IPv6 in the format of DEADBEEF000000000000000000000001:1F90?

[matthiasr]

I don't remember I'm afraid. I hope I configured this on some machine and this is what I got …

[matthiasr]

Actually, reading prometheus/node_exporter#67 I don't think I did. I had no IPv6 example to work off and it probably never worked this way.

[matthiasr]

Paging @juliusv who, if I remember correctly, had a hand or two in the IPv6 support for IPVS :)

[filippog]

@SuperQ these machines run a mix of 4.4 and 4.9 though IIRC we've seen the same with older kernels e.g. 3.16

[juliusv]

@matthiasr I didnt touch this procfs file back then, but I added a Generic Netlink interface to read and write IPVS configs (which was needed because the old sockopt-based interface couldn't accommodate v6 addresses). You can take a look at what the Netlink interface looks like today, maybe it can give you the same answers: https://github.com/torvalds/linux/blob/ca78d3173cff3503bcd15723b049757f75762d15/net/netfilter/ipvs/ip_vs_ctl.c#L2836

https://github.com/torvalds/linux/blob/5924bbecd0267d87c24110cbe2041b5075173a25/include/uapi/linux/ip_vs.h#L279

[matthiasr]

Hokay, I have no idea what how to read those 😆

If the [aaaa:bbbb:…] format is what actually exists in the wild I'm inclined to just roll with it

[juliusv]

SGTM

[filippog]

Confirmed working, thanks a lot @matthiasr ! I've opened prometheus/node_exporter#576 to add this to node_exporter