[Bug report] Net input plugin broken in v1.3.0 on old CentOS versions

[Fiery-Fenix]

Bug report

Relevant telegraf.conf:

# Read metrics about network interface usage
[[inputs.net]]
  ## By default, telegraf gathers stats from any up interface (excluding loopback)
  ## Setting interfaces will tell it to gather these explicit interfaces,
  ## regardless of status.
  ##
  #interfaces = ["eth0"]

System info:

[root@hostA ~]# telegraf --version
Telegraf v1.3.0 (git: release-1.3 2bc5594b44145368823d7aa78bfb753ab51e9235)
[root@hostA ~]# uname -a
Linux hostA 2.6.18-164.el5 #1 SMP Thu Sep 3 03:28:30 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux
[root@hostA ~]# lsb_release -a
LSB Version:    :core-3.1-amd64:core-3.1-ia32:core-3.1-noarch:graphics-3.1-amd64:graphics-3.1-ia32:graphics-3.1-noarch
Distributor ID: CentOS
Description:    CentOS release 5.4 (Final)
Release:        5.4
Codename:       Final
[root@hostA ~]# cat /proc/net/dev
Inter-|   Receive                                                |  Transmit
 face |bytes    packets errs drop fifo frame compressed multicast|bytes    packets errs drop fifo colls carrier compressed
    lo:32108095  555355    0    0    0     0          0         0 32108095  555355    0    0    0     0       0          0
  eth0:5019464820 14784542    0    0    0     0          0     34733 8907551793 12498214    0    0    0     0       0          0

Steps to reproduce:

1. CentOS version 5.4
2. telegraf version 1.3.0 (version 1.2 works fine)
3. telegraf --config /etc/telegraf/telegraf.conf --config-directory /etc/telegraf/telegraf.d/ --input-filter net --test

Expected behavior:

eth0 interface statistics in test output

Actual behavior:

only "all" interface statistic is in test output

Additional info:

System information from machine with newer CentOS release:

[root@hostB ~]# telegraf --version
Telegraf v1.3.0 (git: release-1.3 2bc5594b44145368823d7aa78bfb753ab51e9235)
[root@hostB ~]# uname -a
Linux hostB 2.6.32-696.1.1.el6.x86_64 #1 SMP Tue Apr 11 17:13:24 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
[root@hostB ~]# lsb_release -a
LSB Version:    :base-4.0-amd64:base-4.0-noarch:core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch
Distributor ID: CentOS
Description:    CentOS release 6.9 (Final)
Release:        6.9
Codename:       Final
[root@hostB ~]# cat /proc/net/dev
Inter-|   Receive                                                |  Transmit
 face |bytes    packets errs drop fifo frame compressed multicast|bytes    packets errs drop fifo colls carrier compressed
    lo: 265254324 1809320    0    0    0     0          0         0 265254324 1809320    0    0    0     0       0          0
  eth0: 193887393605 383619914    0    0    0     0          0         0 133942562211 412596235    0    0    0     0       0          0

As you can see in older CentOS there is NO space after interface name "eth0:" in at /proc/net/dev output and I think that's why it's not working with new release of telegraf.

[danielnelson]

shirou/gopsutil#377