Systems

Linux +10 years
Nutanix 5 years
VMware 3 years
SaltStack 3 year
Terraform 2 year
Ceph 4 year
bash.sh +10 years
Regex +10 years
Python 2 years
Iptables Firewall 6 years

Databases

OracleDB +10 years
PostgreSQL 6 years
PGpool 2 years
Barman 2 years
Repmgr 2 years
MySQL 5 years
ProxySQL 3 years
Redis 3 years
MongoDB 3 years

Applications

Apache 10 years
Nginx 8 years
PHP-FPM 5 years
Rundeck 3 years
Asterisk 3 years
Tomcat/Jboss 2 years
Postfix 3 years
PowerMTA 3 years