DocOps by Johannes Hölzel

Hi 👋, I'm Johannes

I talk to humans and machines and specialize in golang, kubernetes as well as automating everything!

As a consultant and developer, I provide services ranging from DevOps to application development and have a history of completing projects on time and within budget. My current focus is on Kubernetes, Golang, and Terraform but I have experience working in various environments.

Growing up with the internet, I uploaded my first websites to Geocities, served as tech-admin for numerous bulletin boards, and have been professionally coding since 2003. After attempting to build my first start-up in 2006, I learned that success would not come simply because I built it. As a result, I earned a bachelor’s degree in economical psychology, which has greatly enhanced my team leadership and communication skills and allows me to view products from multiple perspectives.

What began as a small agency offering server hosting in 2007 has since evolved into a full-service consultancy and freelancing business, serving clients around the world. I started working when servers were primarily dedicated, experienced the virtual server revolution, briefly delved into serverless tech, and am now immersed in the Kubernetes ecosystem and its container technology. My background in psychology gives me unique insights into team leadership and communication, and I have a proven track record of leading and creating successful international teams.

My preferred cloud platforms are Azure and AWS, but I have also worked on other platforms, including bare-metal and everything in between. I enjoy tackling complex problems and have experience with multi-cloud deployments.

I am currently offering my services as a freelancer and would be happy to discuss potential opportunities involving Kubernetes. If you’re looking for someone with seniority and experience in the field, please feel free to reach out. I have extensive experience with Amazon AWS, Microsoft Azure, Hetzner-cloud, DigitalOcean, Contabo and bare-metal Kubernetes, and I am confident in my abilities and can back them up with experience.

All of this makes me an ideal candidate if you are seeking a senior-level professional who is flexible, collaborative, and hands-on. If you would like to see what I have been up to, please check the projects section on LinkedIn.

Tailored secure Kubernetes Solutions with Office 365 Integration

I specialize in crafting custom Kubernetes environments like RKE2, k3s, rke2 and (many) more seamlessly integrated with Office 365 for optimal performance and collaboration. By leveraging Azure AD, I provide centralized identity management that simplifies security and access control. My focus extends to ensuring financial compliance with regulations such as GDPR, SOC2, and FINRA, using Microsoft’s built-in tools for encryption, audit, and data protection. The result? Scalable, secure infrastructures that balance technical agility with compliance, tailored to your business needs.

I also specialize in architecting multi-cloud environments across multiple Hosters like AWS, Hetzner, Contabo, Ionos, DigitalOcean and more. By distributing production systems across multiple cloud providers—not just availability zones—security, failover, and uptime are dramatically increased. Through an access proxy, your team experiences a seamless interface, making multi-cluster management effortless and transparent. Access proxies eliminate the need for direct access to host systems, further enhancing security by controlling and monitoring connections centrally. This abstraction layer not only simplifies multi-cloud management but also generates comprehensive audit logs, offering insights into every interaction with your infrastructure. They are invaluable for compliance, providing a level of detailed auditability that’s often missed in traditional setups. By implementing access proxies, you maintain robust security and meet compliance requirements effortlessly, ensuring transparency and accountability across all systems.

kubernetes experience

Kubernetes cluster types:

• AKS, Bare-metal, Edge server, EKS, Hetzner-cloud, DigitalOcean, Contabo, multi AZ, Single-Node

Distributions:

• Cloud Kubernetes (AKS EKS), Harvester, RKE2, K3S, Rancher desktop, Rancher RKE, Vanilla Kubernetes

Operators created:

• Admission Controllers, Annotation of existing services, Application deployments, MySQL DB deployments, Scaling of deployments depending on the time and day

Interesting accomplishments in Kubernetes

• working with AI workloads in kubernetes
• enabling security compliance through the use of GoTeleport and strict audit logging
• fully “offline” but accessible through an Access Proxy clusters including Frontends linked through GoTeleport.
• RBAC and Role assignment for a financial institution which much more finegrained access policies
• Deployed bare-metal clusters using on-premise hardware
• Implemented CSI-compliant bare-metal clusters
• Integrated BGP Peer with Calico for enhanced networking
• Configured IPV6/IPV4/dual-stack bare-metal clusters using Calico and Cilium
• Executed cluster-to-cluster migrations
• Transitioned from Helm to Kustomize for resource management
• Automated DNS and certificates management with Cert-Manager and ExternalDNS
• Enabled OIDC Single Sign-On (SSO) for both cluster and application access
• Deployed VOIP applications on Kubernetes
• Implemented GitOps using GitLab, GitHub, Bitbucket, and ArgoCD
• Managed bare-metal ingress load balancing using HAProxy and Traefik
• Utilized Kubecost for effective cost management
• Managed storage and backups using Longhorn
• Deployed ARM architecture on Hetzner for the control plane with AMD64 and ARM nodes

Github Excerpts

1. Argo Helm Versioner
   • Utility designed to help manage and maintain Argo CD Applications deployed via Helm charts.
   • Repository
2. kube-probesimr
   • ProbeSim is a lightweight Go application designed to simulate various failure scenarios for Kubernetes liveness and readiness probes.
   • Repository
3. go-wait-for-k8s
   • A utility program written in Go that monitors the readiness of Kubernetes resources like Pods, Jobs, Deployments, StatefulSets, DaemonSets, and ReplicaSets.
   • Repository
4. SpInvalidFileNameFinder
   • A command-line tool written in Go that helps you find and optionally rename files and folders with invalid names for SharePoint.
   • Repository
5. Consoleman
   • A command-line utility that acts like Postman but runs in the console. You can use it to send HTTP requests to APIs and inspect the responses.
   • Repository
6. Simpleapp
   • A simple app that defines a basic Kubernetes app used in trainings, containing a simple MVC structure for packages, a Mux subrouter integration, kube manifests, and an easy-to-learn structure.
   • Repository
7. Auto Updating base images
   • This image is based on mcr.microsoft.com/azure-cli and integrates mongodb-tools in order to easily backup databases in a production AKS.
   • Repository
8. Cronor
   • A Kubernetes cron job image with one task: change a deployment depending on whether it’s day or night. Showcasing how easily the Kubernetes API can be implemented directly into your code in multiple ways.
   • Repository
9. Ingress and Egress with the same IP on Azure and Terraform
   • Repository
10. DevContainers
    • A collection of Dockerfiles for various development environments.
    • Repository

📩 Latest Blog Posts

• 2024-09-05 All roads will lead you to Azure
• 2024-09-05 Gaining Total Control of Your Kubernetes Nodes with Custom Images
• 2024-09-02 Building Resilience with kube-probesim
• 2024-09-01 go_wait_for_k8s
• 2024-09-01 Kuberntes Access Proxies
• 2024-08-31 Streamlining Helm Chart Management with Argo Helm Versioner
• 2023-05-08 Demystifying etcd
• 2023-05-04 Fixing a Kubernetes Namespace Stuck in Terminating State
• 2023-05-01 Kubernetes Headless Services
• 2023-04-25 Embracing the Kubernetes Downward API

Certifications

• Certified Kubernetes Security Specialist (CKS) Complete Course
  • LevelUp360° DevOps | GCP | Terraform | Kubernetes | Ansible on Udemy
  • Kubernetes Cybersecurity
• Azure Kubernetes Service with Azure DevOps and Terraform
  • Kalyan Reddy Daida on Udemy
  • Kubernetes Azure
• AWS Fargate & ECS - Masterclass | Microservices, Docker, CFN
  • Kalyan Reddy Daida on Udemy
  • AWS
• AWS Certified Cloud Practitioner - Complete NEW Course 2021
  • Neal Davis on Udemy
  • AWS
• AWS EKS Kubernetes-Masterclass | DevOps, Microservices
  • Kalyan Reddy Daida on Udemy
  • Kubernetes AWS
• Certified Kubernetes Administrator (CKA) with Practice Tests
  • Mumshad Mannambeth, KodeKloud Training on Udemy
  • Kubernetes
• Mastering Go Programming
  • Packt Publishing on Udemy
  • Golang

Courses

• Configuring and Managing Kubernetes Networking, Services, and Ingress by Anthony Nocentino
  • Kubernetes
• Configuring and Managing Kubernetes Security by Anthony Nocentino
  • Kubernetes
• Creating Custom Resources in Kubernetes by Zachary Bennett
  • Kubernetes
• Deploying and Managing Azure Kubernetes Service (AKS) Clusters By Ben Weissman, and Anthony Nocentino
  • Kubernetes
• Learn terraform by setting up Highly available wordpress
  • Terraform
• Managing Advanced Kubernetes Logging and Tracing by Piotr Gaczkowski
  • Kuberenetes
• Managing Apps on Kubernetes with Istio by Elton Stoneman
  • Kubernetes
• Monitoring and Scaling Applications in Kubernetes By Tapan Ghatalia
  • Kubernetes
• gRPC [Golang] Master Class: Build Modern API & Microservices by Stephane Maarek
  • Golang
• Psychological assessment systems that measure occupational competencies, personality and interests
  • www.therocinstitute.com

• Scrum Master

• Design Thinking

general experience

• Fullstack (Frontend, Backend, APIs, Daemons, Operators, Infrastructure-Orchestration)
• Favorites: Golang, JavaScript, PHP, C#
• Cloud: AWS, Azure, Hetzner, OVH, Contabo, Bare-Metal
• Databases: MySQL , MSSQL, PostgreSQL, TimeScaleDB, Redis, MongoDB
• DevOps: Ansible, Puppet, Terraform, Argo CD, Rancher
• Server: Kubernetes, k3s, K3OS, Harvester, Docker (Swarm), Bare-Metal , Serverless
• Location Networking, VPN (Wireguard, Software, MS-VPN)
• Jira / Redmine / Trello

Languages

Deutsch

• Native or bilingual proficiency

Englisch

• Native or bilingual proficiency

Spanisch

• Limited working proficiency

You can reach me on LinkedIn

Some pictures so its not so boring here ;)

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