test-ssl-cert-check-zabx.sh

#!/bin/bash
#Script that checks ssl certificate on any domain (Script take a list of damains, please specify -p (port) option BEFORE list of your domains.)
# and send notification in zabbix if certificate almost\expiried
#do not need BC calc anymore.

#Written by MentoS

#One big cycle, ends after case cycle (cycle of choosing)
while [ -n "$1" ]
do
#default port value if port not specified will using 443
#port="443"
#choosing options which you specified and processing
case $1 in
-p)
port=$2
;;
-d)
hosts=$@
#sorting by separate every domain with comma for future processing
IFS=', ' read -r -a array <<< "$hosts"
#some debug
#echo "${array[2]}"

#for cycle, take every domain and with openssl client gets begin and end dates of certificate
#after that cycle cuts it and preproccessing in seconds and after some mathematic operations gets number of DAYS BEFORE EXPIRATION
#can take negative value.
for host in "${array[@]}";
do
end_date=`openssl s_client -servername $host -host $host -port $port -showcerts -prexit </dev/null 2>/dev/null |
          sed -n '/BEGIN CERTIFICATE/,/END CERT/p' |
          openssl x509 -text 2>/dev/null |
          sed -n 's/ *Not After : *//p'`
if [ -n "$end_date" ]
then
    end_date_seconds=`date '+%s' --date "$end_date"`
    now_seconds=`date '+%s'`
    #Original:
    #echo "($end_date_seconds-$now_seconds)/24/3600" | bc
    #New:
    end_days=$(((end_date_seconds-now_seconds)/24/3600))
    #echo -e "$end_days"
fi
#lists of domain:days and just domain for futher zabbix proccessing
final+=("$host:$end_days")
fday+=("$end_days")
#some debug
#echo "${final[@]}"
#echo "$host ssl cert expiration date: $end_date"
done

#count min and max value from certs dates 
min=0 max=0
for i in ${fday[@]}; do
    (( $i > max || max == 0)) && max=$i
    (( $i < min || min == 0)) && min=$i
done
#Almost expiried cert
#echo "${final[@]}" | grep -o -E "[a-z0-9]+\.[a-z]+\.*[a-z]+:$min"
echo "${final[@]}" | grep -o -E "[a-z0-9]+\.[.0-9a-z]*[.a-z]*:$min"
#certificate with maximum expiration date 
#Uncomment if you want this option. 
#echo "${final[@]}" | grep -o -E "[a-z0-9]+\.[a-z]+\.*[a-z]+:$max"
#some debug
#echo "min=$min, max=$max"
;;
esac
shift
done