Hi 👋, I'm Johannes
I talk to humans and machines and specialize in golang, kubernetes as well as automating everything!
As consultant and developer I provide services from DevOps to application development and have a history of completing projects on time and in budget. I currently focus on kubernetes, golang and terraform but have seen and worked on multiple environments.
I grew up with the internet, uploaded my first websites to geocities, was tech-admin of a lot of bulletin boards and have been doing professional code since 2003. After trying to build my first start-up in 2006 I realized that they just won’t come only because I built it. Therefore, I have a bachelor economical psychology, which helps me immensely with team leadership and communication but also allows me to view the product from multiple perspectives.
What started out as WordPress and ASP.NET agency with server hosting in 2007 has long since evolved into full service consultancy and freelancing services with clients throughout the globe. I started working when Servers where still mostly dedicated, have lived the revolution of virtual servers, made a short stop at serverless tech and am now invested in the kubernetes ecosystem and its containers.
My preferred clouds are Azure and AWS, but I have worked on others and also like to tame bare-metal and everything in-between. I love solving difficult issues and have worked on multi cloud deployments before.
All this makes me perfect if you are looking for someone with seniority, that is flexible, plays well with others but also likes to get his hands dirty. If you would like to see what I have been up to, please check the projects section on LinkedIn.
kubernetes experience includes
Kubernetes cluster types:
- bare-metal
- AKS
- EKS
- Hetzner-cloud
- Edge server
- Single-Node
- Multi-node
- Multi-node, multi AZ
Distributions:
- Vanilla Kubernetes
- K3S
- Rancher RKE
- Micro-k8s
- Rancher desktop
- Harvester
Created operators:
- MySQL DB deployments
- Application deployments
- Annotation of existing services
- Scaling of deployments depending on the time and day
Interesting things:
- CSI compliant bare metal clusters
- BGP Peer integration with Calico
- IPV6/IPV4/dualstack bare-metal clusters with Calico
- Cluster to cluster migrations
- Helm to kustomize migrations
- automated dns and certificates (certmanager/externaldns)
- OIDC SSO Login for the cluster and its applications
- Deployment of VOIP Applications to kubernetes
- GitOps with Gitlab, Github, bitbucket, ArgoCD
- Bare-metal ingress load balancing with ha-proxy and Traefik
- Cost management depending on kubecost
- Storage and Backups with longhorn
Github excerpts:
- Simpleapp is a simple app that defines a basic kubernetes app i use in my trainings. It contains a simple MVC structure for packages, a Mux subrouter integration, kube manifests and an easy to learn structure. https://github.com/jhoelzel/simpleapp
- 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. https://github.com/jhoelzel/docker-azure_cli-mongodb_tools
- Cronor is a kubernetes cron job image with one task: change our deployment depending if it’s day or night. This is a showcase of how easily the kubernetes api can be implemented directly into your code in multiple ways. https://github.com/jhoelzel/cronor
- Ingress and Egress with the same IP on Azure https://github.com/jhoelzel/aks_ingress_egress_same_ip
- DevContainers: Over the years I noticed that I have been throwing away a lot of nice dockerfiles and this repository is deemed to change that.https://github.com/jhoelzel/devcontainer
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
You can reach me on LinkedIn
