Ian is available for hire
Hire IanIan Cotter-Llewellyn
Verified Expert in Engineering
Systems Developer
Dublin, Ireland
Toptal member since July 8, 2021
Bio
Ian is a senior Linux systems engineer with 20+ years of experience delivering production systems across broadcast media, fintech, and startups. His background spans web applications, APIs, distributed systems, on-premise, and cloud-based infrastructure. Recent work focuses on AWS-based platforms, Kubernetes, and infrastructure-as-code, with an emphasis on zero-downtime workload migration, debugging application misbehavior, and optimizing workloads in high-stakes, business-critical environments.
Portfolio
Freelance
Amazon EKS, APIs, Amazon Web Services (AWS), Autoscaling Groups, Amazon EC2...
Freelance
AWS Lambda, Amazon S3 (AWS S3), Flask, Python, APIs, iCal, User Requirements
RTÉ Group
Management, IT Support, Communication
Experience
- Networking - 20 years
- Linux - 20 years
- SSL Certificates - 15 years
- Amazon EC2 - 15 years
- Python 3 - 15 years
- GitHub - 14 years
- Kubernetes - 5 years
- Terraform - 5 years
Preferred Environment
Python 3, Kubernetes, Terraform, Let's Encrypt, Amazon EC2, Amazon EKS, Amazon RDS, SSL Certificates, GitHub, GitLab
The most amazing...
...feeling comes when back-out plans for a large-scale, high-impact project cut-over are superseded by the flawless execution of the cut-over plan itself.
Work Experience
DevOps Engineer
2019 - PRESENT
Freelance
- Built, operated, and optimized Kubernetes clusters supporting financial analytics, ETL pipelines, and brokerage workloads, including human-in-the-loop order processing.
- Supported clusters scaling to 6,000+ vCPUs and 30+ TB RAM, balancing cost and performance across heterogeneous workloads.
- Configured and deployed GitLab instances and runners to manage dev teams' projects. Built CI/CD pipelines, including parallel execution, to increase release velocity using GitLab and GitHub.
- Identified and remediated over-permissioned IAM policies, reducing unintended access exposure and reducing management burden through improved policy design.
- Migrated Amazon Elastic Block Store (EBS), Amazon RDS, and Amazon S3 data between accounts, often including special cases: large volumes, tens of millions of objects, zero-downtime, etc.
- Led clients' initiatives: devised project execution plans, liaised with stakeholders and third-party vendors when necessary, and presented findings, including supporting materials as required.
- Developed working proofs-of-concept for business development strategies: AWS Workspaces, Sentry, Apache Spark, Coder, microsites, and internal workflow improvement tools.
- Improved platform reliability by resolving intermittent cluster DNS failures and deployment instability.
- Advised on right-sizing resource requests and node-pool configuration, improving cluster efficiency.
- Established structured incident analysis and post-mortem practices, improving understanding of failure modes and future mitigation.
Technologies: Amazon EKS, APIs, Amazon Web Services (AWS), Autoscaling Groups, Amazon EC2, Diagrams, Continuous Delivery (CD), Proof of Concept (POC), CI/CD Pipelines, Terragrunt, Terraform, AWS Lambda
One-stop Solutions Architect and Developer
2026 - 2026
Freelance
- Examined the client's workflow around manual handling of bookings from multiple online channels and explored options for automation.
- Architected a viable solution, both software and infrastructure, that fit into the client's OpEx constraints.
- Delivered a working prototype for review and approval.
- Deployed final automated workflow based on AWS Lambda and S3, including stats providing insight into the system's ongoing performance.
Technologies: AWS Lambda, Amazon S3 (AWS S3), Flask, Python, APIs, iCal, User Requirements
Broadcast Operations First Line Response Manager
2018 - 2019
RTÉ Group
- Implemented a regime of business continuity rehearsals to ensure all members of the support team were familiar with the steps of the disaster scenario playbooks.
- Coordinated troubleshooting efforts of the local support team and Avid support to workaround and resolve a major post-upgrade newsroom playout bug.
- Investigated weather graphics issues that led to missed and delayed weather bulletins. Familiarized with and standardized bulletin preparation procedures. Liaised with ChyronHego support and Imagine Communications vendors to eradicate problems.
- Reduced occurrences of schedule overruns and commercial breaches through the use of Six Sigma instance analysis.
Technologies: Management, IT Support, Communication
Transmission Control Supervisor | Radio
2012 - 2017
RTÉ Group
- Managed a highly skilled team in charge of providing operations support, technical maintenance, and development of production tools and workflows for live broadcasting across nine national radio services. Prepared budgets and executed capital plans.
- Modernized audio infrastructure, transitioning to high-bandwidth audio-over-IP (AoIP). Designed redundant networks to achieve end-to-end latency of less than three milliseconds.
- Led control system software development to perform real-time, automated control of the infrastructure.
- Led the technical group for the national, industry-wide Irish Radioplayer project that saw 38 radio stations across Ireland join forces in one mobile app. Liaised with stations to ensure streams and sites conformed to their technical obligations.
- Implemented Amazon Alexa flash briefing skill for use as the default news provider for devices sold in Ireland. Worked to Amazon's launch-date deadline, ensuring that the production values were upheld, as well as intuitive CMS and reliable delivery.
- Supported the visual radio pilot for RTÉ Radio and led implementation for long-term studio and rack-room installs. Created an infrastructure template that could be repeated for further studios, allowing the overall system to scale up with demand.
Technologies: Audio, Python 3, Bash Script, Amazon Web Services (AWS), Cisco, Dante, WheatNet-IP
Project Engineer | Radio
2005 - 2012
RTÉ Group
- Designed bare-metal, on-premise, Red Hat clusters to handle radio production database with all music, audio clip, and radio production metadata. Cluster configuration storage variations: fiber, DRBD, and cloud storage. Provisioned with kickstarts.
- Developed compliance logger replacement for nine radio services, including network and storage redundancy and a simple, fast API for retrieving the stream segments. The system was so popular it was used for long-term archive and program production.
- Initiated a project to overhaul the national radio website to modernize its design and make it mobile responsive in advance of Google's Mobilegeddon. Managed third-party design and handled delivery and deployment with local front-end devs.
- Homogenized audio production for the web. Designed an automated, configurable client to download, normalize, transcode, deliver on-demand, and catch up programs for listeners. Built on Python and Django on top of Virtualenv and a Postgres cluster.
Technologies: JavaScript, PHP, CSS, Linux, Distributed Replicated Block Device (DRBD), Bash Script, Python 3, Fault Tolerance, Database Replication, APIs
Experience
AudioFile | Broadcast Recording System
http://github.com/ian-llewellyn/AudioFileA bi-located, fault-tolerant audio recording, storage, and serving system operating 24/7/365, providing mission-critical service to thousands of users.
I architected the solution within the confines of the corporate environment. This included clustered VMware origin servers with SCSI attached shared storage presented as RDMs to the origin VMs and consumed as LVM PVs. I designed the API and the front end (a web-based audio player), outsourced the front-end build, and developed the back end myself.
The back end consisted of a PHP codebase for the API that leveraged server-side binaries to split the audio and stream it to the client. I also wrote a Python program to synchronize the central storage with the satellite recorders every 750 milliseconds using HTTP range requests. This turned out to be extremely efficient and was rolled out further to a separate radio production system to ensure excellent reliability. I instrumented the system so that operators could monitor various parameters, including disk usage and sync latency.
The API was designed to be used by other applications to automate tasks (cutting audio for online publication), provide long-term archive access, and facilitate the production of future radio programs.
I architected the solution within the confines of the corporate environment. This included clustered VMware origin servers with SCSI attached shared storage presented as RDMs to the origin VMs and consumed as LVM PVs. I designed the API and the front end (a web-based audio player), outsourced the front-end build, and developed the back end myself.
The back end consisted of a PHP codebase for the API that leveraged server-side binaries to split the audio and stream it to the client. I also wrote a Python program to synchronize the central storage with the satellite recorders every 750 milliseconds using HTTP range requests. This turned out to be extremely efficient and was rolled out further to a separate radio production system to ensure excellent reliability. I instrumented the system so that operators could monitor various parameters, including disk usage and sync latency.
The API was designed to be used by other applications to automate tasks (cutting audio for online publication), provide long-term archive access, and facilitate the production of future radio programs.
Continuous Delivery 3-tier Web Service
http://github.com/ian-llewellyn/realworld-devops-demoI developed a continuous delivery (CD) pipeline and infrastructure as code (IaC) to provision a three-tier, cloud-based web app capable of serving thousands of back-end requests per second. The stack was operated on by three distinct roles—DevOps engineers, operations teams, and app developers.
Stack included monitoring (Prometheus) and log collection (Grafana Loki) as well as automated backups (AWS Backup) of these metrics, logs, and the application's underlying database (PostgreSQL).
I used GitHub Actions to enable continuous delivery of code triggered by pushes and pull requests that modify the application codebase. The actions include building a Docker image for the front-end or back-end service as necessary, testing the new image, tagging it with the appropriate version number (Docker Hub), and initiating a production rollout of the upgraded version on Kubernetes (Amazon EKS).
We automatically secured all public endpoints with TLS (cert-manager and Let's Encrypt).
Scaling was handled semi-automatically at the client's request by providing a simple management script that an in-house Ops team could call to scale up and down as they saw fit. The cluster then scaled AWS resources as needed.
Stack included monitoring (Prometheus) and log collection (Grafana Loki) as well as automated backups (AWS Backup) of these metrics, logs, and the application's underlying database (PostgreSQL).
I used GitHub Actions to enable continuous delivery of code triggered by pushes and pull requests that modify the application codebase. The actions include building a Docker image for the front-end or back-end service as necessary, testing the new image, tagging it with the appropriate version number (Docker Hub), and initiating a production rollout of the upgraded version on Kubernetes (Amazon EKS).
We automatically secured all public endpoints with TLS (cert-manager and Let's Encrypt).
Scaling was handled semi-automatically at the client's request by providing a simple management script that an in-house Ops team could call to scale up and down as they saw fit. The cluster then scaled AWS resources as needed.
Education
2001 - 2004
Bachelor's Degree in Electrical and Electronic Engineering
Queen's University Belfast - Belfast, Northern Ireland
Certifications
JANUARY 2019 - PRESENT
Six Sigma Yellow Belt
University of Limerick
OCTOBER 2011 - PRESENT
Red Hat Certified Engineer
Red Hat
FEBRUARY 2011 - PRESENT
Linux From Scratch Builder
linuxfromscratch.org
Skills
Libraries/APIs
Terragrunt, iCal
Tools
Let's Encrypt, GitHub, Git, GitLab, GitLab CI/CD, GitLab Runner, Terraform, Amazon EKS, Helm, Apache Airflow, Distributed Replicated Block Device (DRBD), Grafana, Certbot, Sentry
Languages
Bash Script, Bash, Python 3, Python, JavaScript, PHP, CSS
Platforms
Amazon EC2, Linux, Red Hat Linux, Kubernetes, Docker, Amazon Web Services (AWS), AWS Lambda, Apache2, Azure
Storage
Amazon S3 (AWS S3), Database Replication
Paradigms
Management, Continuous Delivery (CD), DevOps
Frameworks
Flask
Industry Expertise
Lean Six Sigma
Other
SSL Certificates, Linux Internals, Communication, Infrastructure as Code (IaC), CI/CD Pipelines, Linux Administration, Cloud, Amazon RDS, Networking, IT Support, Fault Tolerance, Relational Database Services (RDS), Autoscaling Groups, OpenID Connect (OIDC), GitHub Actions, Software, Audio, APIs, Cisco, Dante, WheatNet-IP, Prometheus, Requirements, Diagrams, Proof of Concept (POC), User Requirements
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