Sergiu is available for hire
Hire SergiuSergiu Vrancean
Verified Expert in Engineering
DevOps Engineer and Developer
Chicago, IL, United States
Toptal member since May 6, 2025
Bio
Sergiu is a dedicated and experienced DevOps engineer passionate about streamlining software development and operations to deliver high-quality, reliable applications. His journey in the world of technology has been marked by a deep commitment to automating processes and optimizing deployment pipelines using tools like Kubernetes, Docker, AWS, Terraform, Ansible, GitHub Actions, and Jenkins CI/CD pipelines. Sergiu will be a great addition to any team.
Portfolio
Delta Air Lines
Infrastructure, Cloud Deployment, Terraform, Kubernetes, Kubernetes Security...
Change Healthcare
Linux, OWASP, Docker, GitHub Actions, Google Cloud Platform (GCP)...
Morningstar
Kubernetes, Linux, AWS IoT, Ingres, AWS WAF, Amazon RDS
Experience
- Linux - 6 years
- Infrastructure - 6 years
- Terraform - 6 years
- AWS IoT - 6 years
- Cloud Deployment - 6 years
- Kubernetes - 6 years
- Argo CD - 4 years
- Kubernetes Security - 3 years
Availability
Full-time
Preferred Environment
Linux, CI/CD Pipelines, DevOps
The most amazing...
...project I've completed involved migrating legacy applications to microservices.
Work Experience
DevOps | Site Reliability Engineer
2021 - PRESENT
Delta Air Lines
- Developed and maintained Terraform modules for cloud infrastructures utilizing AWS, such as Amazon VPC, subnets, security groups, EC2 instances, Route 53, ELB, S3, EBS, and EKS.
- Defined configuration baselines and implemented Rego policies to enforce OPA Gatekeeper security policies.
- Created and maintained fully automated continuous integration (CI), continuous delivery (CD), and continuous deployment pipelines in multiple environments using GitHub Actions/GitLab CI/CD.
- Deployed essential Kubernetes services like Ingress, StatefulSets, Services, NetworkPolicies, and ConfigMaps, enabling efficient networking and persistent storage.
- Monitored application services using Grafana, Prometheus, and Datadog to collect and analyze logs and metrics and created alerts based on nodes, pods, and services from Kubernetes clusters, enabling effective performance monitoring and analysis.
- Assessed and improved infrastructure and processes to increase efficiency and reduce downtime.
- Deployed and configured Hashicorp Vault on Kubernetes Clusters for secret and token management.
- Collaborated with software development and testing team members to design and develop robust solutions to meet company requirements for functionality, scalability, and performance.
- Implemented Argo CD in the pipeline across all clusters to enforce GitOps best practices. Managed Argo CD RBAC permission-breaking teams by projects and environments. Configured Argo CD components.
- Applied and configured ExternalDNS for the Kubernetes cluster to automate AWS Route 53 DNS configuration.
Technologies: Infrastructure, Cloud Deployment, Terraform, Kubernetes, Kubernetes Security, AWS IoT, Service Meshes, Amazon EKS, Amazon Web Services (AWS)
DevOps Engineer
2019 - 2021
Change Healthcare
- Created Dockerfiles and built Docker images for microservices to run on development, test, and production environments.
- Upgraded Kubernetes development, QA, and production environments to a newer version.
- Monitored Kubernetes resources using Prometheus and Grafana. Troubleshot failed deployments and restored them promptly.
- Deployed cert-manager on GKE, enabling efficient management of SSL certificates.
- Troubleshot and resolved issues with Kubernetes (GKE) clusters and workloads, including networking, storage, and resource constraints.
- Implemented logging platform ElasticSearch, Logstash, Kibana, and Beats (ELK Stack).
- Wrote and managed Ansible playbooks to automate deployment and configuration management tasks across multiple servers.
- Developed and maintained Kubernetes manifests and Helm charts to deploy and configure Kubernetes resources and applications.
- Utilized Terraform to manage and optimize GCP resources, streamlining provisioning and configuration.
Technologies: Linux, OWASP, Docker, GitHub Actions, Google Cloud Platform (GCP), Active Directory (AD), Apache Kafka, Dynamic Load Balancing, Ansible
Cloud Engineer
2018 - 2019
Morningstar
- Created, configured, and managed cloud infrastructures using Terraform web services like VPC, EC2, Auto Scaling, ELB, CloudFront, CloudWatch, availability zones, subnets, routing tables, NAT gateways, DNS, users, security groups, roles, and policies.
- Built and maintained Kubernetes clusters using Helm and Terraform on development, test, and production environments.
- Designed and applied a highly available and fault-tolerant infrastructure on the AWS cloud.
- Managed users, groups, and permissions in AWS IAM, ensuring proper access control and maintaining security standards.
- Created Dockerfile from scratch. Built Docker images and pushed them to the artifact registry.
- Improved, optimized, and expanded the cloud infrastructure to enhance performance and cost-effectiveness.
- Developed and adhered to cloud solutions based on industry best practices, ensuring reliability and scalability.
Technologies: Kubernetes, Linux, AWS IoT, Ingres, AWS WAF, Amazon RDS
Experience
Legacy Transformation
As part of Delta Air Lines' digital transformation initiative, this project focused on modernizing the legacy flight operations support platform to enhance real-time decision-making and operational resilience. The new system supports dynamic crew scheduling, aircraft availability tracking, and weather-integrated route optimization built on a cloud-native microservices architecture for scalability and fault tolerance.
RESPONSIBILITIES AND CONTRIBUTIONS
• Implemented CI/CD pipelines using GitHub Actions and Argo CD to enable automated, zero-downtime deployments to Kubernetes clusters on AWS EKS.
• Containerized microservices using Docker and managed Helm chart deployments through Kustomize for environment-specific configurations.
• Automated infrastructure provisioning and scaling using Terraform with AWS resources like EC2, RDS, S3, and IAM.
• Collaborated with development and SRE teams to enforce GitOps workflows and improve deployment frequency and rollback safety.
RESPONSIBILITIES AND CONTRIBUTIONS
• Implemented CI/CD pipelines using GitHub Actions and Argo CD to enable automated, zero-downtime deployments to Kubernetes clusters on AWS EKS.
• Containerized microservices using Docker and managed Helm chart deployments through Kustomize for environment-specific configurations.
• Automated infrastructure provisioning and scaling using Terraform with AWS resources like EC2, RDS, S3, and IAM.
• Collaborated with development and SRE teams to enforce GitOps workflows and improve deployment frequency and rollback safety.
Certifications
MARCH 2023 - PRESENT
Certified Kubernetes Application Developer
Linux Professional Institute
JANUARY 2023 - PRESENT
AWS SysOps Administrator
AWS
DECEMBER 2022 - PRESENT
Terraform Associate
Hashicorp
DECEMBER 2022 - PRESENT
Certified Kubernetes Administrator
Linux Professional Institute
NOVEMBER 2022 - PRESENT
AWS Solutions Architect Associate
AWS
Skills
Tools
Amazon EKS, Ansible, Terraform
Languages
Bash Script, Python
Paradigms
DevOps
Platforms
Kubernetes, AWS IoT, Linux, Amazon Web Services (AWS), Docker, Google Cloud Platform (GCP), Apache Kafka
Storage
Cloud Deployment, Google Cloud, Ingres
Other
Infrastructure, CI/CD Pipelines, Argo CD, Kubernetes Security, Service Meshes, OWASP, GitHub Actions, Active Directory (AD), Dynamic Load Balancing, AWS WAF, Amazon RDS
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