I have been into the industry for more than 10 years managing customer infrastructure.
Containerization : Kubernetes, Docker
Cloud Computing : AWS, Azure
Virtualization : Xen, KVM, VMware
Cluster Suite : DRBD, Heartbeat, Keepalived
Config Management : Puppet
Data Analysis : Elasticsearch, Logstash, Kibana, Grafana
Monitoring Tool : Nagios, CheckMK
Scripting : Bash/Shell Scripting, Perl Scripting
Database Administration : MySQL
Webserver : Apache, Nginx
Load Balancer : Layer 4/7 LB using HAProxy
Backup Tool : CommVault