Viacheslav Krailo

Progressed from DevOps Engineer to Senior DevOps Engineer; company scaled from ~€500M to €1.8B+ in annual revenue during tenure
Incident Response & Reliability
Traced a Kubernetes API server dropping 82% of requests to a misconfigured admission-policy controller generating 14,000 malformed calls/second — not the initially suspected node upgrade.
Diagnosed a production database outage to long-running analytical queries exhausting replica CPU; executed emergency vertical scaling while shipping the permanent fix.
Remediated two consecutive CVSS 10.0 RCE vulnerabilities via GitOps-driven image updates, with zero service disruption.
Led the observability migration from New Relic to Grafana Cloud via OpenTelemetry, evaluating 20+ vendor criteria to remove collector-level vendor lock-in across production workloads.
Zero-Downtime Data Migrations (solo, live production)
Migrated 15-20TB+ of production data with zero downtime across six datastore types — including 10+ sharded MongoDB clusters and a 50+ node Elasticsearch cluster — using a repeatable pattern: auth introduced behind a proxy in optional mode, verified via live traces, then enforced with zero required application redeploys.
Migrated ClickHouse's coordination layer twice (ZooKeeper → ClickHouse Keeper → Raft) across sharded StatefulSets totaling 5,000+ GB.
Migrated 100+ MySQL replicas and 50+ CloudSQL instances bidirectionally via Cloud SQL migration jobs, alongside full Kafka cluster migrations with topic/partition state reconciliation.
Migrated 15-20+ Kafka, RabbitMQ, Gearman's,
CI/CD & GitOps at Scale
Configured and optimized 1,000+ CI/CD pipelines across GitLab CI and ~10 Jenkins instances; migrated GitLab itself into Kubernetes.
Authored 100+ Helm charts and custom shell-operators; built the Prometheus/VictoriaMetrics alerting stack from scratch.
Migrated hundreds of FluxCD GitOps setups across clusters — fully zero-downtime, orchestrated via Terraform/Terragrunt.
API Gateways & Traffic Management
Eliminated 82% of API request drops and resolved critical performance degradation by diagnosing and fixing a misconfigured admission-policy controller generating 14,000 malformed calls/second on Kubernetes (GKE).
Achieved zero downtime during live production migrations of 15–20TB+ of data across 6 datastore types (including 10+ sharded MongoDB clusters and a 50+ node Elasticsearch cluster) by implementing proxy-based authentication layers with zero app redeploys.
Eliminated coordination bottlenecks by successfully migrating ClickHouse's coordination layer (ZooKeeper → ClickHouse Keeper → Raft) across sharded StatefulSets totaling 5,000+ GB.
Optimized global inbound traffic and enforced rate-limiting by configuring and scaling advanced API gateways (Kong, Traefik, Envoy/Istio, and Apache APISIX) across production microservices.
Maintained zero-disruption security posture by rapidly remediating two consecutive CVSS 10.0 RCE vulnerabilities using automated GitOps (FluxCD) image updates.
Successfully migrated 100+ MySQL replicas and 50+ CloudSQL instances bidirectionally, alongside full Kafka cluster migrations with complete topic/partition state reconciliation.
Accelerated deployment cycles by configuring and optimizing 1,000+ CI/CD pipelines across GitLab CI and Jenkins, and migrating GitLab core directly into Kubernetes.
Unified global observability by migrating infrastructure monitoring from New Relic to Grafana Cloud via OpenTelemetry (OTel), removing vendor lock-in across production workloads.