We have our standart set of software
We prefer CentOS.
We use systemd-nspawn and openvz for simple web projects due to low overhead, simple and fast hardware migration and fast backup recovery.
We build CI/CD projects using k8s, Docker, Gitlab.
We use ansible for configuration management.
We are highly experienced in working with most popular DBs, such as as MySQL (Percona Server, MariaDB), and PostgreSQL, and NoSQL (Redis, MongoDB). We build HA and FT solutions using DB clusters.
We chose Gitlab as a CI/CD tool, but we can use Jenkins and TeamCity too.
For analytics and monitoring, we use Zabbix and Prometheus. But we can use M/Monit, Elasticsearch, Fluentbit/Fluentd too.
For developing of automatisation scripts, we chose Ansible.