Nikos Tzelvenzis
Verified Expert in Engineering
DevOps Engineer and Developer
Thessaloniki, Greece
Toptal member since July 15, 2020
Nikos is a DevOps engineer and infrastructure designer with several years of hands-on experience, which includes building a high-traffic platform with at least 7 million users. On that project, the whole infrastructure was horizontally scaled based on the load and traffic. The challenge there had to do with the size of traffic—specifically auditing and logging—due to the size of logs, etc. were much larger than usual. It's safe to say whatever your DevOps needs are, Nikos can handle them.
Portfolio
Experience
Availability
Preferred Environment
Firefox, Visual Studio Code (VS Code), Bash, Linux
The most amazing...
...project was making a scalable way to restore all files in 2 hours without service interruption after an accidental deletion of 20 million files in S3 storage.
Work Experience
Director of DevOps
Schoox Inc
- Created a new secure network within the cloud infrastructure and helped the company archive security certifications to take on new and more significant customers.
- Designed and enabled a monitoring-and-audit platform that helped the support department to answer customer's questions more confidently.
- Transformed the build and deploy procedure. Previously, the company used git pull as the deployment method, which caused HTTP errors; now, the node's upgrades happen without traffic and with zero HTTP errors.
DevOps Engineer
Datajolt Limited
- Solved a problem in EKS deployments with network issues on an AWS Application Load Balancer as an ingress resource.
- Suggested a better way to keep logs for the application that was distributed and deployed in the EKS cluster. Listened to the company's needs and suggested two to three solutions based on the budget.
- Checked the existing security state of the infrastructure and evaluated data access based on how they gave me access to the AWS account.
Senior DevOps Engineer
NebulOS, Inc.
- Solved problems in a Ceph cluster with node outages. The cluster was unstable, and all writes were disabled, so it was re-balanced.
- Added four new nodes in the existing cluster and updated the OpenStack to a newer version. Set up new virtual networks and started to work with new clients on this cluster. Created the new OpenStack images for windows and provisioned them.
- Supported the existing Oracle VM cluster with other technical members during US off-work hours.
DevOps Engineer
Piggy, LLC
- Changed, working as a developer focused on security, the application's access to AWS from static keys to IAM roles.
- Designed and wrote Lambda function to rotate the credentials of RDS databases automatically.
- Reviewed and fixed the security groups and the access to infrastructure.
DevOps AWS Engineer
ZYP.ONE GmbH
- Designed and created the entire environment (production, staging, and testing) with Terraform and created networking with OpenVPN to access the environment without the need to enable public access.
- Migrated the database to RDS, configured database backups, and unique dump exports to S3 with an ECS service.
- Installed and configured the Jenkins CI/CD system with a master node and dynamic slave nodes.
- Improved the automated pipeline to work better with CI and prepared the CD portion for testing and staging environments.
Software Developer | Oracle Database Specialist | Infrastructure Architect
Logismos SA
- Deployed OpenStack as a private cloud solution for the company.
- Converted storage to be more central with Ceph and with the added benefit that maintenance could happen without interruption to services.
- Designed and implemented an integration service between two systems in near real-time between multi-sites in different countries worldwide.
- Installed and configured an Oracle database with a standby service and automatic backup without interruptions for two different hosts.
Experience
Recovery of 20 Million Deleted Files in Amazon S3 Buckets
Worker Daemon in Python
Scalable Logging Parser
SSO Authentication with All Internal Services
SOC2 Certification
This team involved the reports and procedures to keep any security aspects and be tracked to audit trails. Finally, we apply any changes requested by the audit team.
Education
Bachelor's Degree in Electronics
Technical University - Thessaloniki, Greece
Certifications
AWS Certified SysOps Administrator — Associate
AWS
Skills
Libraries/APIs
OpenID
Tools
Amazon Elastic Block Store (EBS), AWS ELB, AWS CLI, Terraform, AWS, Ansible, Helm, Amazon EKS, OpenVPN, Amazon Simple Queue Service (SQS), Jenkins, AWS, AWS, AWS, VPN, GitHub, AWS, ELK Stack
Frameworks
AWS, Flask
Paradigms
DevOps, Agile Development, Continuous Integration (CI), DevSecOps, Automation
Platforms
Amazon EC2, OpenStack, Kubernetes, Docker, AWS, Azure Design, Linux, Firefox Development, Oracle Development, Visual Studio Development, AWS ALB, Ubuntu, AWS Lambda
Storage
Amazon S3, Ceph, MongoDB, Data Centers
Languages
Python, Bash, PHP, Java, SAML
Other
Amazon Route 53, System Administration, Electronics, Microcontrollers, Circuit Design, OKTA, SSO Engineering, Security, Cloud Engineering, Networks, CI/CD Pipelines, AWS RDS, Scaling, Gunicorn
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