Jeff Hemmen, Developer in Esch-sur-Alzette, Luxembourg
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Jeff Hemmen

Verified Expert  in Engineering

Consul Developer

Esch-sur-Alzette, Luxembourg
Toptal Member Since
January 28, 2022

Jeff is a driven and earnest person with an analytical mind, a notorious inner compass, and an obsession with scalability and security. He is a very experienced DevOps engineer who has had amazing opportunities in terms of clients and partners. Jeff has represented AWS and HashiCorp as a consultant and trainer, which is a particularly unique experience.


Jeff Hemmen Ltd
HashiCorp, Hashistack, Jenkins, F5 Networks, Amazon Web Services (AWS), Python...
ECS Group
Amazon Web Services (AWS), Kubernetes, Vault, Consul, HashiCorp, Docker, Python...
Amazon Web Services (AWS), Amazon Kinesis, Capistrano, Docker, Python...




Preferred Environment

MacOS, Slack, Vi, Visual Studio Code (VS Code), Amazon Web Services (AWS), Windows 10, Python

The most amazing...

...achievement I’ve had is not a single project, but my tenacity and drive to continuously learn new technologies, and to understand how to create value from them!

Work Experience


2022 - PRESENT
Jeff Hemmen Ltd
  • Devised and implemented security hardening features for the corporate HashiCorp Vault clusters.
  • Negotiated customer and stakeholder deliverables and expectations.
  • Delivered training (HashiCorp Vault and Terraform) to customers around the globe.
Technologies: HashiCorp, Hashistack, Jenkins, F5 Networks, Amazon Web Services (AWS), Python, DevOps, Cloud Architecture, Cloud Infrastructure

DevOps & Continuous Delivery Consultant

2019 - PRESENT
ECS Group
  • Navigated a significant change of scope and an unexpected additional governance process during an engagement with a London-based stock exchange while keeping within profit margins.
  • Advised multiple financial sector clients on a secure setup for onboarding hundreds of teams in a scalable manner, using Vault, Terraform, and CI/CD.
  • Delivered training and workshops on several different technologies and paradigms, internally and externally, in English, German, and French.
Technologies: Amazon Web Services (AWS), Kubernetes, Vault, Consul, HashiCorp, Docker, Python, DevOps, Cloud Architecture, Cloud Infrastructure, Azure

Platform Engineer

2018 - 2019
  • Collaborated closely with the data scientist as a platform engineer.
  • Reduced technical debt and made deployment pipelines more robust.
  • Assumed duties as a data engineer and assisted with various tasks.
Technologies: Amazon Web Services (AWS), Amazon Kinesis, Capistrano, Docker, Python, Message Queues, DevOps, Cloud Architecture, Cloud Infrastructure

DevOps Engineer

2017 - 2018
  • Designed and set up cloud infrastructure for startup clients. This included VMs running a DataStax Enterprise (DSE) cluster, permissions, networking and firewalls, a site-to-site VPN, and a monitoring suite, all in two identical environments.
  • Deployed a monitoring environment in a heavily regulated environment from scratch, using Ansible.
  • Learned a new technology, using Cassandra for a distributed database and gained certification within weeks of joining.
Technologies: Terraform, Cassandra, Apache Kafka, Message Queues, DevOps, Amazon Web Services (AWS), Cloud Architecture, Cloud Infrastructure, Azure

DevOps Engineer

2015 - 2016
  • Designed and executed strategy for database migration with minimum downtime.
  • Used PagerDuty for scheduling, monitoring and alerting systems, remote login, and troubleshooting for on-call duties.
  • Set up the complete network infrastructure for an office move with DSL, PPPoE, WiFi, NAT, NAS, and a firewall.
Technologies: Ansible, Bash, Linux, Networking, Iptables, Vyatta, Jenkins, Cloudflare, DevOps

I created a POC WebCrawler in Python 3, originally as an interview project for Monzo Bank. It was output as structured text and unit tests were provided as part of the Python docstring. There was no concurrency with standard logging to stderr.

Integrating Ansible with Terraform
A sample project to illustrate how Terraform and Ansible can be used together. (Initially, as an audition for a web-based training company.) This project is a one-click deployment of a small MediaWiki stack. The stack consists of two AWS EC2 instances, one AWS RDS instance, and one AWS ALB (plus ancillary resources). The focus is on remote management, especially passing the database credentials from Terraform to Ansible. Secrets are generated randomly during deployment and never transferred unencrypted between Terraform and Ansible.

This is a hash-effectual self-maintaining upwards-recursive file system. It was my undergraduate graduation project, a file system that calculates hashes for files and folders, so you can quckly compare two structures on different machines. The project used Fuse.
2014 - 2015

Master of Research in Security Science

University College London - London, UK

2013 - 2014

Master's Degree in Forensic Speech Science

University of York - York, UK

2009 - 2012

Bachelor's Degree in Computing Science

University of Aberdeen - Aberdeen, UK


Certified Ethical Hacker


JULY 2022 - JULY 2024

Vault: Authorized HashiCorp Instructor


JULY 2022 - JULY 2024

Terraform: Authorized HashiCorp Instructor



VMware Certified Professional - Application Modernization 2022


APRIL 2022 - APRIL 2024

Vault: Certified HashiCorp Implementation Partner (CHIP)


APRIL 2022 - APRIL 2024

Terraform: Certified HashiCorp Implementation Partner (CHIP)


MARCH 2022 - MARCH 2024

HashiCorp Certified: Vault Operations Professional Exam Contributor


JULY 2021 - JULY 2024

Certified Kubernetes Administrator

The Linux Foundation

JULY 2020 - MARCH 2023

HashiCorp Certified: Consul Associate


MAY 2020 - MAY 2023

AWS Certified Solutions Architect Associate


APRIL 2020 - APRIL 2023

Certified Kubernetes Application Developer

The Linux Foundation


HashiCorp Vault Intermediate



HashiCorp Terraform Advanced



HashiCorp, Terraform, Vault, Ansible, Jenkins, Capistrano, Fuse, Slack, Hashistack, VMware vSphere


DevOps, Object-oriented Programming (OOP)


Amazon Web Services (AWS), Kubernetes, Docker, Linux, Apache Kafka, MacOS, Visual Studio Code (VS Code), VMware Tanzu, Azure


Bash, Python, Python 3, C




Cloud Architecture, Cloud Infrastructure, Secret Management, Consul, Service, Infrastructure as Code (IaC), Data, Cloud Services, Orchestration, Scheduling, Containers, Service Mesh, Network Automation, Security, Computer Science, Networking, Iptables, Cloud, APIs, Forensic Science, Speech Analytics, Linguistics, Languages, Acoustics, Vyatta, Cloudflare, Amazon Kinesis, HTTP, File Systems, Vi, Windows 10, Hacking, Mission Control, Training, F5 Networks, Message Queues, AWS DevOps

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