17+ years of experience in IT Infrastructure, Systems Administration, Networking, DevOps, DevSecOps and Site Reliability Engineering.

I design, automate, secure and operate reliable IT infrastructure — from Linux servers, networks and virtualization platforms to Docker, Kubernetes, CI/CD, Infrastructure as Code, Cloud and Observability.

My professional background combines Systems Administration + Networking + Telecommunications + DevOps, allowing me to approach infrastructure from both the systems and network perspectives.

🇬🇧 English · 🇪🇸 Español

I am a DevOps / DevSecOps Engineer and SRE with more than 17 years of experience working with Linux-based infrastructure, production environments, networking and IT operations.

My experience spans traditional Systems Administration and Networking as well as modern DevOps, DevSecOps, SRE, automation and cloud-native technologies.

I focus on building infrastructure that is:

• ⚙️ Automated
• 🔐 Secure
• 📈 Observable
• 🚀 Reliable
• 📦 Containerized
• 🌐 Network-aware
• 💰 Cost-efficient
• 🔄 Easy to operate and maintain

I enjoy solving infrastructure problems, automating repetitive tasks, improving operational reliability and helping teams adopt better engineering practices.

I help teams automate software delivery and improve deployment workflows.

• GitLab CI/CD
• GitHub Actions
• CI/CD pipeline design
• Deployment automation
• GitOps
• Release automation
• Environment management
• Container-based deployments

Linux infrastructure design, administration, troubleshooting and optimization.

• Linux server administration
• Production troubleshooting
• System hardening
• Service configuration
• Performance optimization
• Bash automation
• Web servers
• Database infrastructure
• Infrastructure maintenance

My networking background is one of the areas that differentiates my infrastructure profile.

I can work across both systems and network layers, including:

• LAN / WAN
• TCP/IP
• DNS
• DHCP
• VPN
• Firewalls
• Routing
• NAT
• pfSense
• IPTables
• Proxy infrastructure
• Squid
• LDAP
• Network troubleshooting
• Infrastructure connectivity
• Telecommunications infrastructure

This combination allows me to troubleshoot infrastructure problems beyond the application or server layer.

Design, deployment and administration of infrastructure environments.

• Bare Metal
• Proxmox VE
• VMware ESXi
• Linux infrastructure
• Virtual machines
• Docker
• Docker Compose
• Infrastructure consolidation
• Server optimization
• Cloud infrastructure

Containerization and orchestration for modern infrastructure.

• Docker
• Docker Compose
• Kubernetes
• Containerized applications
• Production workloads
• Container networking
• Infrastructure automation
• Deployment strategies
• Reliability and scalability

Integrating security into the software delivery and infrastructure lifecycle.

• Snyk
• OWASP Dependency-Check
• OWASP ZAP
• Nuclei
• Nikto
• SonarQube
• Vulnerability management
• Dependency analysis
• Security scanning
• Shift-Left Security
• Security automation

Helping teams understand what is happening inside their infrastructure.

• Prometheus
• Grafana
• Alertmanager
• Zabbix
• Uptime Kuma
• Monitoring
• Alerting
• Incident response
• Troubleshooting
• MTTR optimization

Reducing manual operations through automation and reproducible infrastructure.

• Terraform
• OpenTofu
• Ansible
• Bash
• Python
• Infrastructure as Code
• Configuration management
• Operational automation

These results come from my professional experience optimizing CI/CD, observability, security automation and infrastructure operations.

TCP/IP · DNS · DHCP · VPN · Firewalls · pfSense · IPTables · Squid · LDAP · LAN/WAN

My technical profile combines DevOps and cloud-native technologies with Linux, networking, virtualization and security infrastructure.

I am building a portfolio of practical infrastructure and DevOps projects covering:

• GitLab CI/CD pipelines
• Automated Docker deployments
• Multi-environment deployments
• GitOps workflows
• CI/CD security integration

• Production-style Kubernetes clusters
• High Availability architectures
• Container orchestration
• Networking and ingress
• Persistent storage
• Backup and disaster recovery

• Terraform / OpenTofu
• Ansible automation
• Reproducible infrastructure
• Server provisioning
• Configuration management

• Linux server administration
• Reverse proxies
• VPN infrastructure
• Firewall configuration
• DNS / DHCP
• Network troubleshooting
• Infrastructure security

• Prometheus
• Grafana
• Alertmanager
• Infrastructure monitoring
• Application monitoring
• Incident response

• SAST
• Dependency scanning
• DAST
• Vulnerability management
• Security automation
• Shift-Left Security

More projects will be published here as the portfolio evolves.

IT / SRE / DevOps Engineer
Jan 2023 – Jun 2026

Designed, automated and operated Linux production infrastructure.

Key achievements:

• Reduced CI/CD lead time by 60%
• Increased deployment frequency by 3×
• Centralized observability across 100+ Linux servers
• Reduced MTTR by 25%
• Reduced critical pre-release CVEs by approximately 90%
• Automated infrastructure and operational processes
• Worked with Docker, GitLab CI/CD, Ansible, Terraform/OpenTofu and Bash
• Supported containerized workloads
• Contributed to infrastructure cost optimization
• Mentored junior engineers and delivered technical workshops

IT / SRE Engineer
2021 – 2023

• Linux infrastructure administration
• Production troubleshooting
• Networking environments
• Docker-based workloads
• Monitoring and reliability improvements
• Bash and operational automation

Founder & Administrator
2012 – Present

Founder and administrator of a technical community focused on:

• Linux
• Systems Administration
• Networking
• Infrastructure
• DevOps
• Technical documentation
• Knowledge sharing
• Professional development

🌐 https://www.sysadminsdecuba.com

My professional experience and responsibilities are detailed in my CV.

• Linux Foundation — Introduction to Linux
• Linux Foundation — Open Source Technical Documentation Essentials
• Linux Foundation — Creating Effective Documentation for Developers
• Linux Foundation — Introduction to GitOps
• Linux Foundation — Introduction to DevOps and Site Reliability Engineering
• Linux Foundation — Introduction to DevSecOps for Managers

• Linux Professional Institute certification
• Getting Started with OpenTofu
• Crash Course Kubernetes for Absolute Beginners

Electronics Technician
Osvaldo Herrera Telecommunications Polytechnic Institute

2010 – 2012

This telecommunications and electronics background complements my later experience in Linux, networking, infrastructure and DevOps.

I am available for projects involving:

• Linux infrastructure
• DevOps implementation
• CI/CD automation
• Docker and Kubernetes
• Infrastructure as Code
• Ansible automation
• Terraform / OpenTofu
• Networking
• VPN and firewall infrastructure
• Infrastructure monitoring
• Observability
• DevSecOps
• Security automation
• Infrastructure optimization
• Production troubleshooting
• Technical consulting

If you need help designing, automating, securing or operating your infrastructure, feel free to get in touch.

📧 Email: koratsuki.nijuusan@gmail.com

💼 LinkedIn: https://www.linkedin.com/in/leon-leslie/

🌐 SysAdmin Community: https://www.sysadminsdecuba.com

Soy Ingeniero DevOps / DevSecOps y SRE, con más de 17 años de experiencia en infraestructura TI, administración de sistemas, redes, servicios telemáticos, DevOps, DevSecOps y operaciones de producción.

Mi perfil combina la experiencia tradicional de Administración de Sistemas y Redes con tecnologías modernas de:

• DevOps
• DevSecOps
• SRE
• Automatización
• Cloud
• Contenedores
• Kubernetes
• Infrastructure as Code
• Observabilidad

Mi objetivo es construir y operar infraestructuras que sean:

• ⚙️ Automatizadas
• 🔐 Seguras
• 📊 Observables
• 🚀 Confiables
• 📦 Contenerizadas
• 🌐 Bien conectadas
• 💰 Eficientes
• 🔄 Sencillas de operar y mantener

Diseño y automatización de procesos de integración y despliegue continuo.

• GitLab CI/CD
• GitHub Actions
• Diseño de pipelines
• Automatización de despliegues
• GitOps
• Automatización de releases
• Gestión de ambientes

• Administración de servidores Linux
• Troubleshooting
• Hardening
• Configuración de servicios
• Optimización
• Bash
• Servidores web
• Bases de datos
• Mantenimiento de infraestructura

Uno de mis principales diferenciadores es la combinación de Networking + Systems Administration + DevOps.

Experiencia en:

• LAN / WAN
• TCP/IP
• DNS
• DHCP
• VPN
• Firewalls
• Routing
• NAT
• pfSense
• IPTables
• Squid Proxy
• LDAP
• Troubleshooting de redes
• Conectividad de infraestructura
• Servicios telemáticos
• Infraestructura de telecomunicaciones

• Bare Metal
• Proxmox VE
• VMware ESXi
• Linux
• Virtualización
• Docker
• Docker Compose
• Consolidación de infraestructura
• Optimización de servidores
• Cloud Infrastructure

• Docker
• Docker Compose
• Kubernetes
• Containerización
• Redes de contenedores
• Orquestación
• Automatización
• Alta disponibilidad
• Escalabilidad

• Snyk
• OWASP Dependency-Check
• OWASP ZAP
• Nuclei
• Nikto
• SonarQube
• Vulnerability Management
• Security Scanning
• Dependency Analysis
• Shift-Left Security

• Prometheus
• Grafana
• Alertmanager
• Zabbix
• Uptime Kuma
• Monitoring
• Alerting
• Incident Response
• MTTR Optimization

• Terraform
• OpenTofu
• Ansible
• Bash
• Python
• Infrastructure as Code
• Configuration Management
• Operational Automation

• Linux Foundation — Introduction to Linux
• Linux Foundation — Open Source Technical Documentation Essentials
• Linux Foundation — Creating Effective Documentation for Developers
• Linux Foundation — Introduction to GitOps
• Linux Foundation — Introduction to DevOps and Site Reliability Engineering
• Linux Foundation — Introduction to DevSecOps for Managers
• Linux Foundation — Getting Started with OpenTofu
• Crash Course Kubernetes for Absolute Beginners
• Linux Professional Institute Certification

Técnico en Electrónica
Instituto Politécnico de Telecomunicaciones Osvaldo Herrera

2010 – 2012

Esta formación constituye una base importante para mi experiencia posterior en redes, infraestructura, sistemas y DevOps.

Estoy disponible para proyectos relacionados con:

• Administración Linux
• DevOps
• CI/CD
• Docker
• Kubernetes
• Terraform / OpenTofu
• Ansible
• Infrastructure as Code
• Redes
• VPN
• Firewalls
• DNS / DHCP
• Monitoring
• Observability
• DevSecOps
• Automatización
• Optimización de infraestructura
• Troubleshooting
• Consultoría técnica

📧 Email: koratsuki.nijuusan@gmail.com

💼 LinkedIn: https://www.linkedin.com/in/leon-leslie/

🌐 SysAdmin Community: https://www.sysadminsdecuba.com

Construyendo infraestructura confiable. Automatizando operaciones. Protegiendo el ciclo de entrega.