iptables input plugin use_lock error

[voiprodrigo]

Hi,
Versions: Telegraf 1.11.4 / CentOS 7.6

This is how telegraf calls iptables when use_lock is true:

execve("/usr/sbin/iptables", ["/usr/sbin/iptables", "-wnvL", "OUTPUT", "-t", "filter", "-x"], [/* 10 vars */] <unfinished ...>

Telegraf errors with exit code 2 in the log.

This is why:

# /usr/sbin/iptables -wnvL FORWARD -t filter -x
iptables v1.4.21: wait seconds not numeric

Solution: separate the -w flag from the rest of the flags:

# /usr/sbin/iptables -w -nvL FORWARD -t filter -x
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
    pkts      bytes target     prot opt in     out     source               destination