Comparison of status variables that are strings doesn't work as expected

[Ovais Tariq]

[root@centos6_01 plugins]# ./pmp-check-mysql-status --version
Percona Monitoring Plugins pmp-check-mysql-status 1.0.3

Let's check the status variable "wsrep_on" which does not return an integer:
[root@centos6_01 plugins]# ./pmp-check-mysql-status -H pxc01 -l root -p test -P 3306 -x wsrep_on -C "==" -c OFF
CRIT wsrep_on = ON | wsrep_on=ON;;OFF;0;
[root@centos6_01 plugins]# ./pmp-check-mysql-status -H pxc01 -l root -p test -P 3306 -x wsrep_on -C "==" -c ON
CRIT wsrep_on = ON | wsrep_on=ON;;ON;0;

Comparing with an integer also doesn't work:
[root@centos6_01 plugins]# ./pmp-check-mysql-status -H pxc01 -l root -p test -P 3306 -x wsrep_on -C "!=" -c 1
CRIT wsrep_on = ON | wsrep_on=ON;;1;0;
[root@centos6_01 plugins]# ./pmp-check-mysql-status -H pxc01 -l root -p test -P 3306 -x wsrep_on -C "!=" -c 1
CRIT wsrep_on = OFF | wsrep_on=OFF;;1;0;

Let's check another status variable "Compression" which also does not return an integer:
[root@centos6_01 plugins]# ./pmp-check-mysql-status -H pxc01 -l root -p test -P 3306 -x Compression -C "==" -c ON
CRIT Compression = OFF | Compression=OFF;;ON;0;
[root@centos6_01 plugins]# ./pmp-check-mysql-status -H pxc01 -l root -p test -P 3306 -x Compression -C "==" -c OFF
CRIT Compression = OFF | Compression=OFF;;OFF;0;

So the comparison and checks of non-integer status variables do not work as expected.

This primarily comes from this function I suppose:
155 # ########################################################################
156 # Compares the variable to the thresholds. Arguments: VAR CRIT WARN CMP
157 # Returns nothing; exits with OK/WARN/CRIT.
158 # ########################################################################
159 compare_result() {
160 local VAR="${1}"
161 local CRIT="${2}"
162 local WARN="${3}"
163 local CMP="${4}"
164 echo 1 | awk "END {
165 if ( \"${CRIT}\" != \"\" ) {
166 if ( ${VAR} ${CMP} ${CRIT:-0} ) {
167 exit $STATE_CRITICAL
168 }
169 }
170 if ( \"${WARN}\" != \"\" ) {
171 if ( ${VAR} ${CMP} ${WARN:-0} ) {
172 exit $STATE_WARNING
173 }
174 }
175 exit $STATE_OK
176 }"
177 }

The problem is with the condition on line 166 and line 170, if I quote ${VAR} and ${CRIT:-0} and ${WARN:-0} in both the lines, it works as expected:
[root@centos6_01 plugins]# ./pmp-check-mysql-status -H pxc01 -l root -p test -P 3306 -x wsrep_on -C "==" -c OFF
CRIT wsrep_on = OFF | wsrep_on=OFF;;OFF;0;
[root@centos6_01 plugins]# ./pmp-check-mysql-status -H pxc01 -l root -p test -P 3306 -x wsrep_on -C "==" -c OFF
OK wsrep_on = ON | wsrep_on=ON;;OFF;0;

However then the comparison of arithmetic values will get broken.

[Roman Vynar (roman-vynar)]

You are right.

Since we can't compare strings and numbers the same way I decided to add a new transformation option to the script.
Currently -T could be pct only.
I am going to add -T str to compare strings.

As it is now:
$ ./nagios/bin/pmp-check-mysql-status -x slave_exec_mode -C '==' -c bla
CRIT slave_exec_mode = STRICT | slave_exec_mode=STRICT;;bla;0;

Will be fine when specifying -T str:
$ ./nagios/bin/pmp-check-mysql-status -x slave_exec_mode -T str -C '==' -c bla
OK slave_exec_mode (str) = STRICT | slave_exec_mode=STRICT;;bla;0;