Senior DevOps / Infrastructure Engineer

Job Description We are looking for an experienced Infrastructure / DevOps Engineer to manage, optimize, and troubleshoot our production environment hosted in our own data center. Our platform includes a large-scale mail application, distributed databases, load-balanced backend services, CI/CD pipelines, storage clusters, monitoring systems, and native mobile applications. The ideal candidate should have strong experience in Linux server administration, networking, performance optimization, load balancing, mail infrastructure, database replication, and distributed systems. Current Infrastructure - Mail platform powered by Mailcow (email sending and receiving) - Multiple application servers with load balancing - Frontend web infrastructure with load balancing - Backend API infrastructure with load balancing - 4 PostgreSQL/MySQL database servers with replication and load balancing - 2 CI/CD pipeline servers - Ceph storage cluster for media and file management - Monitoring and alerting servers - Android and iOS applications consuming backend APIs - Self-hosted data center environment Primary Responsibilities - Analyze and resolve infrastructure performance bottlenecks - Troubleshoot network latency, bandwidth limitations, and timeout issues - Optimize communication between application servers, database servers, Mailcow, Ceph, and load balancers - Monitor and improve API response times under concurrent user load - Investigate and resolve slowdowns occurring when multiple users access the system simultaneously - Review server architecture and recommend infrastructure improvements - Optimize database replication and query performance - Analyze load balancer configuration and traffic distribution - Improve system scalability, availability, and reliability - Implement performance monitoring, alerting, and capacity planning - Support CI/CD pipelines and deployment automation - Maintain security, backups, and disaster recovery processes Required Skills - Linux Administration (Ubuntu, Debian, CentOS, RHEL) - Mail Server Management (Mailcow, Postfix, Dovecot) - Networking (TCP/IP, DNS, Routing, Firewall, NAT, VPN) - Load Balancers (HAProxy, Nginx, Traefik, PgPool, etc.) - Database Replication and Performance Tuning - Ceph Storage Administration - Docker and Containerized Services - CI/CD Pipelines - Monitoring Tools (Prometheus, Grafana, Zabbix, ELK, etc.) - Performance Profiling and Troubleshooting - High Availability and Distributed Systems Current Challenge The infrastructure is already deployed and operational. However, we are experiencing performance issues under concurrent usage. Examples include: - API timeouts - Slow response times when 10+ users access the system simultaneously - Delays when backend services communicate with Mailcow - Potential networking, bandwidth, load balancing, or infrastructure bottlenecks The engineer's first objective will be to identify the root cause of these performance issues and implement solutions to ensure stable, scalable, and high-performance operation. Engagement - Full-Time / Part-Time / Contract - Remote - Immediate Joining Preferred Please share: - Relevant infrastructure experience - Previous projects involving mail systems or large-scale distributed environments - Availability - Expected compensation