All cases | Portfolio

.NET Backend Observability & Telemetry Integration

.NET Backend Observability: Telemetry Integration & Performance Optimization Client E-commerce platform with high-load .NET 8 backend Challenge The .NET backend had no observability — no distributed tracing, no centralized metrics, no structured logging. Finding slow requests required manual log digging. The team needed full OpenTelemetry integration: trace propagation from Ingress through .NET to downstream services (PostgreSQL, Redis, RabbitMQ, HTTP upstreams), automatic slow-query detection, and a path to optimize P99 latency.

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AWS → Another Cloud Migration

Cloud Infrastructure Migration from AWS to a Cost-Optimized Private Cloud Client Confidential Challenge The client needed to migrate their entire AWS infrastructure to an alternative cloud provider to reduce costs and eliminate vendor lock-in. The key requirements were minimal downtime, zero functionality loss, and a reliable rollback strategy. Solution 1. Audit & Planning Full inventory of AWS resources (EC2, RDS, S3, VPC) Service mapping: AWS → target cloud equivalents Phased migration plan with clear milestones Rollback strategy for each stage 2. Infrastructure Preparation Terraform for IaC on the target platform VPC, subnets, and security groups configuration Managed PostgreSQL and Redis deployment Object Storage setup (S3-compatible) 3. Data Migration Database replication via DMS S3 → Object Storage sync Docker image transfer to private Container Registry Full validation on staging environment 4. Production Cutover DNS failover for gradual traffic switching Real-time metrics monitoring during cutover AWS kept on standby for emergency rollback Final cutover completed in 2 hours Technologies AWS Terraform Prometheus Grafana GitLab CI Results ✅ Cost reduction: 40% savings (from $15k to $9k/month) ✅ Downtime: only 2 hours vs. 8 hours planned ✅ Vendor independence: full exit from AWS with no functionality loss ✅ Performance: maintained at the same level post-migration ✅ Compliance: data residency and security requirements met

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CI/CD & Production Infrastructure for a Social App

Production Infrastructure & CI/CD for a Social App Launch Client Puzzle Master — a social matching platform Challenge The startup had a production-ready Nest.js backend and Angular frontend, but zero infrastructure: deployments were manual, there was no CI/CD, no monitoring, no backups, and no separation between dev and prod environments. The goal was to build a complete DevOps stack from scratch before the public launch. Solution 1. Application Containerization Multi-stage Dockerfile for backend (Nest.js + Prisma, non-root user) Multi-stage Dockerfile for frontend (Angular 12, legacy OpenSSL, Nginx for static assets) Docker Compose full stack: PostgreSQL 15, Redis 7, imgproxy, Nginx Healthchecks and depends_on for correct startup ordering Isolated dev and prod environments in /opt/dev and /opt/prod 2. GitLab CI/CD Migration of repository from Bitbucket to GitLab Pipeline for backend and frontend: build → push → deploy GitLab Container Registry for Docker image storage Automatic deploy to dev on every push; manual trigger for prod SSH deployment to VPS via SSH_PRIVATE_KEY 3. Nginx Reverse Proxy Environment-agnostic config via envsubst for dev/prod parity SSL/TLS (TLSv1.2, TLSv1.3) with Cloudflare certificates Routing: /api/* → backend:4000, /* → frontend:80 www → root domain redirect (301) Separate imgproxy stack with SSL termination 4. Security (Ansible) Server hardening via Ansible: SSH key-only auth, root login disabled UFW Firewall: only ports 80, 443, and custom SSH open Database accessible only via SSH tunnel All secrets stored in GitLab CI/CD variables 5. Monitoring Prometheus + Grafana with automated dashboard provisioning Exporters: Node, cAdvisor, Postgres, Redis, Nginx, Blackbox 5 Grafana dashboards: server, Docker containers, PostgreSQL, Redis, Nginx Alertmanager with Slack/webhook integration; alerts on CPU/RAM/Disk/API/SSL 6. Database Backups Automated pg_dump every hour gzip compression and upload to S3-compatible object storage (Cloudflare R2) Prometheus backup metrics: success status, size, timestamp Alerts: DatabaseBackupMissing, DatabaseBackupFailed, DatabaseBackupSizeAnomaly Technologies GitLab CI Docker Ansible Prometheus Nginx PostgreSQL Results ✅ Deploy: git push to main → automatic build and deploy to server ✅ Environments: full dev/prod isolation on a single VPS ✅ Monitoring: 5 dashboards, alerts across 6 categories ✅ Backups: automated hourly pg_dump to Cloudflare R2 ✅ Security: UFW, key-based SSH, database inaccessible from outside ✅ Scalability: architecture ready for database extraction to a dedicated server

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CI/CD & Production Infrastructure for a Web Application

Production Infrastructure & CI/CD for a Company Website Client A manufacturer of branded research products that needed a website to present its product catalog to customers Challenge The developers had written the code of a conventional web application (NestJS backend + Next.js frontend), but infrastructure was completely missing: manual deployments, no CI/CD, no server setup, no monitoring, no backups and no separation between test and production environments. The goal was to build a complete DevOps stack from scratch: GitLab CI/CD, a self-hosted server, two isolated environments, HTTPS, monitoring, alerting and automated backups.

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CI/CD with GitLab + Kubernetes: deploy in 10 minutes

CI/CD automation: from 2 hours to 10 minutes per deploy Client E-commerce startup, 5-person engineering team Challenge Manual deployment took 2 hours Frequent release errors No fast rollback path Required: CI/CD automation, GitOps, fast rollback Solution Self-hosted GitLab GitLab CI pipeline (Build → Test → Deploy) Managed Kubernetes in Yandex Cloud Flux CD for GitOps Technologies GitLab Docker Kubernetes Helm Flux CD Results ✅ Deploy time: from 2 hours to 10 minutes (12x) ✅ Errors: −90% ✅ Deploy frequency: from 1/week to 10+/day ✅ Rollback time: from 1 hour to 2 minutes

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