dm: detect if raid devices present

[glensc]

Fixes: #138, #158, #142, #170

---

Existing systems having dm active:

• sudo rules already existed, continues to run

Existing systems having dm inactive (no raids present):

• sudo rules still missing, plugin will not activate dm plugin

[glensc]

without updated sudo rules (because dm is not active), this would yield sudo warnings, but does not affect exit code:

# sudo -H -u nagios ./check_raid-4.0.7-3-g304ec8c.pl 

We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:

    #1) Respect the privacy of others.
    #2) Think before you type.
    #3) With great power comes great responsibility.

sudo: no askpass program specified, try setting SUDO_ASKPASS

We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:

    #1) Respect the privacy of others.
    #2) Think before you type.
    #3) With great power comes great responsibility.

sudo: no askpass program specified, try setting SUDO_ASKPASS
OK: arcconf:[Controller:Optimal, Logical Device 0(sodom):Optimal, Drives: 3LQ1WG5N,3LQ1WGC0=Online]

# echo $?
0

[glensc]

some alternative solution to avoid sudo errors:

1. run sudo -l
2. process that output for matching commands

this way the plugin won't produce sudo warnings on stderr (some nagios versions include stderr in plugin output afaik)

# sudo -H -u nagios sudo -l
Matching Defaults entries for nagios on xylia:
    !tty_tickets, !requiretty, !tty_tickets

User nagios may run the following commands on xylia:
    (root) NOPASSWD: /usr/bin/ipmitool sdr dump /var/spool/nagios/check_ipmi.sdr
    (root) NOPASSWD: /usr/bin/ipmitool -S /var/spool/nagios/check_ipmi.sdr sdr
    (root) NOPASSWD: /sbin/arcconf GETSTATUS 1
    (root) NOPASSWD: /sbin/arcconf GETCONFIG * AL
    (root) NOPASSWD: /usr/sbin/iptables -n -t filter -L INPUT

[glensc]

to create test env for lvm-dm tests, follow this note: #130 (comment)

modprobe dm-mod 
modprobe dm-raid
modprobe dm-mirror 
modprobe raid1
modprobe raid5
modprobe raid6

LVC="lvcreate -L 28m --alloc anywhere"
$LVC --type raid1 -n raid1 sys
$LVC --type raid5 -n raid5 -i 2 sys
$LVC --type raid6 -n raid6 -i 3 sys
$LVC --type mirror -n mirror-mirrorlog-core --mirrorlog core sys
$LVC --type mirror -n mirror-mirrorlog-disk --mirrorlog disk sys
$LVC --type mirror -n mirror-mirrorlog-mirrored --mirrorlog mirrored sys

dmsetup table |grep -e raid -e mirror |sort

to remove those devices:

lvremove /dev/sys/mirror-mirrorlog-core -f
lvremove /dev/sys/mirror-mirrorlog-disk -f
lvremove /dev/sys/mirror-mirrorlog-mirrored -f
lvremove /dev/sys/raid1 -f
lvremove /dev/sys/raid5 -f
lvremove /dev/sys/raid6 -f

[glensc]

made sudo less noisy if sudo rules not present: 9552372

# sudo -H -u nagios ./check_raid.sh
sudo: a password is required
sudo: a password is required
check_raid UNKNOWN - No active plugins (No RAID found)

[glensc]

i think this is better what is out there now. so merging

[glensc]

some users report that such approach is still not good. sudo will spam root mail about unmatched sudo accesses:

mantis.example.org : Sep 21 14:48:27 : nagios : a password is required ; TTY=pts/0 ; PWD=/etc/nagios/nrpe.d ; USER=root ; COMMAND=/sbin/dmsetup status
mantis.example.org : Sep 21 14:48:27 : nagios : a password is required ; TTY=pts/0 ; PWD=/etc/nagios/nrpe.d ; USER=root ; COMMAND=/sbin/dmsetup status --noflush