Andreas Steffan - Lead Developer

Recommended expert

Hamburg, Germany

Experience

Sep 2023 - Mar 2024

7 months

Hamburg, Germany

Lead Developer

Software

Expansion of document management system with standard CMIS (Content Management Interoperability Services) interface
Implementation of CMIS core services such as navigation, access rights, search, CRUD operations, and versioning in Java
Implementation based on RESTful / OpenAPI services
Delivery as fat-jar and native container image
Deployment on-premises and serverless as Azure Container Application with Terraform
Improved team autonomy through infrastructure engineering and short feedback loops
Observability with OpenTelemetry, Azure Monitor, and Azure Logic Apps
Introduction of Terraform and trunk-based development processes
Quality assurance with BDD tests in C# using SpecFlow and Testcontainers
Azure DevOps pipeline integration tests
Introduction of cloud deployment processes
Cloud and Terraform training for employees

Mar 2023 - Apr 2023

2 months

Hamburg, Germany

Lead Chaos Developer

Public

Set up a chaos engineering environment with LitmusChaos
Implemented observability with the Prometheus stack
Implemented chaos workflows with Argo Workflows for two applications to build a basic understanding of chaos engineering
Introduced disturbances: latency, service outages
Ultimate goal: improving application resilience

Nov 2022 - Sep 2023

11 months

Hamburg, Germany

Lead Developer/Architect

Insurance

Designed on-premises OpenShift (OKD) Kubernetes cluster environments
Declarative provisioning on vSphere with Terraform, ArgoCD, and Nix
Security-driven isolation of environments (sandbox, dev, int) with a subnet per cluster
Integration between ArgoCD and Terraform with one ArgoCD instance per cluster
Provided Terraform execution environment using Nix
Observability with Datadog and the Prometheus stack
Provided image registry through AWS ECR
Employee training

Sep 2022 - Oct 2022

2 months

Hamburg, Germany

Lead Developer Continuous Delivery

Food

Designed and implemented GitOps deployment processes for AWS EKS (Kubernetes)-based microservices with Flux and Terraform
Kubernetes integration with AWS IAM
Implemented continuous integration pipelines with GitHub Actions
Integrated Flux with Terraform
Inter-service communication mostly asynchronous via AWS SNS and AWS SQS
Connected third-party shop catalog eventing via AWS EventBridge
Implemented observability with Datadog
Slack integration for alerting and deployment events
Implemented service mesh with Traefik Enterprise

Apr 2022 - Jul 2022

4 months

Hamburg, Germany

Lead Developer Cloud Infrastructure

Warehouse Technology

Designed and implemented GCP infrastructure as part of a multi-cloud strategy
Designed and implemented landing zones
Implemented deployment with Azure DevOps and Terraform
Implemented alerting via MS Teams with ClojureScript
Implemented serverless tagging with Go
Employee training on Terraform

Jun 2021 - Apr 2022

11 months

Hamburg, Germany

Lead Developer Cloud/Continuous Delivery

Retail

Design and implementation of a GitOps change process for Kubernetes and GCP resources
Improving team autonomy through infrastructure engineering
Implementing GitOps for Solr resources using Clojure/ClojureScript
Implementing index feedback with machine learning
Continuous integration with GitHub Actions
Operating Solr via operator
Deployments across three stages
Implementing k6 load tests for Black Friday and the Super Bowl
Alerting with OpsGenie, Google Cloud Operations, and MS Teams
Integrating Prometheus with Google Cloud Operations metrics
Implementing fast recovery (critical scenarios) via rebuild / restore / reindex
Implementing a search read cache with GCP Redis
Implementing a canary migration with Apigee
Training team members in Terraform, Kubernetes, and operations

Mar 2021 - Jun 2021

4 months

Hamburg, Germany

Lead Developer Continuous Delivery Kubernetes ETL

Finance

Deployment on Google Kubernetes Engine (GKE)
Designing and implementing continuous delivery for Apache Airflow / Spark workloads
Implementing continuous delivery first with Helmfile, then with Flux
Implementing CI with GitHub Actions

Jan 2020 - Feb 2021

1 year 2 months

Hamburg, Germany

Platform Engineer

Logistics

Building a platform team to support feature teams
Improving application lead times
Deploying and operating various Kubernetes clusters: OpenShift PaaS, Kubespray + Ansible, Telekom CCE
Covering disciplines such as observability, authentication/authorization (SSO), networking, key management, storage, databases, continuous integration/delivery, messaging
Greenfield creation of GCP infrastructure with Terraform, Cloud Build, and GitLab
Recovering from a major data center incident over the Pentecost holiday in shifts with a war room

Jul 2019 - Jan 2020

7 months

Hamburg, Germany

Developer / Infrastructure Architect

Mechanical Engineering

Planning and decommissioning of a branch vSphere on-premises infrastructure and applications
Designing and building infrastructure and applications on AWS and Azure
Migrating services: file service, business applications, terminal servers, Exchange mail server, Netscaler ADC, Veeam Backup
Migrating VPN
Setting up AWS IAM, EC2, Route 53, S3, Lambda, SES, CloudWatch, AWS Backup
Integrating Azure Active Directory as an identity provider with MFA
Setting up Office 365 services

Jan 2018 - Jun 2019

1 year 6 months

Hamburg, Germany

Lead Developer Kubernetes Infrastructure

Finance

Designing and implementing a highly available and scalable on-premises platform for the consumer document archive with Kubernetes
Evaluating numerous cloud-native solutions in a short time
Setting up a CI/CD process based on GitOps principles
Selecting and configuring storage, networking, and observability solutions

Sep 2017 - Feb 2018

6 months

Hamburg, Germany

Lead Developer Document Management Platform

Finance

Designed and implemented a headless consumer document archive for several million users based on the Alfresco Content Services platform and OpenAPI
Implemented functionality for lifecycle, users, metadata extraction, search, transformations, and access control

Aug 2014 - Oct 2014

3 months

Hamburg, Germany

Lead Developer Content Management

Education

Designed and implemented management of personal documents (exams, applications, certificates) for students and lecturers in an online campus of a university
Implemented student lifecycle, document capture, search for editorial staff, student view, and authentication
Integrated into the website
Set up Linux server infrastructure

May 2013 - Aug 2013

4 months

Hamburg, Germany

Developer Content Management

Pharma

Designed and implemented an invoice storage system based on Alfresco ECM and CMIS
Replicated content from the ERP system
Implemented search
Enriched PDF documents with metadata from the ERP system
Matched user master data with Active Directory
Handled authentication through Active Directory

Feb 2013 - Apr 2014

1 year 3 months

Hamburg, Germany

Lead Developer Content Management

Technical Services

Designed and implemented document management and workflow solution for technical inspection and testing services
Coordinated contractors and clients through a general contractor for technical services
Imported service orders via REST API
Handled processing and monitoring of a process by contractors and clients
Set up processes for different document types like briefings and protocols
Built a multi-tenant solution with proper access control

Jan 2012 - Dec 2017

6 years

Hamburg, Germany

Lead Developer Content Management

Entertainment

Designed and implemented a system to manage concert content (images, audio, video, documents) for different channels (websites, mobile)
Implemented functionality for lifecycle, search, access control, and delivery
Implemented REST services (for UI and online shop)
Set up on-premises Linux-based server infrastructure

Jan 2012 - Dec 2013

2 years

Hamburg, Germany

Grails Application Developer

Mail Order

Implementation of a shared shopping cart application with the Grails framework and Groovy
Features for group buyers, co-buyers and employees
Communication with surrounding shop system via REST and SOAP interfaces
Implementation of lifecycle for shopping carts and items, co-buyer master data, and merging of shopping carts
Implementation of access control, fraud detection, and email sending

Nov 2011 - Oct 2012

1 year

Hamburg, Germany

Lead Developer Content Management

Insurance

Design and implementation of a content management system for online help for insurance agencies using Alfresco ECM
Providing HTML-based content to about 2500 agencies in a dedicated Java desktop application over VPN
Implementation of features for lifecycle, in-context editing, content aggregation, search functions, workflow management, and publishing

Jan 2006 - Jan 2018

12 years 1 month

Hamburg, Germany

Lead Developer Java

Mechanical Engineering

Design and implementation of a multi-tenant quote workflow and marketing application
Integration with an ERP system
Tracking of quotes
Managing documents in Alfresco ECM
Integration of a system for automatic price calculation of binding quotes
Data synchronization with ERP systems
Setting up Linux-based server infrastructure

Oct 2002 - Feb 2006

3 years 5 months

Hamburg, Germany

Lead Developer Infrastructure/Continuous Delivery

Finance

New implementation of the website of an online bank/broker including transaction, market data, member, and public areas
Building new Linux servers and network infrastructure
Implementing sign-on in the public area
Components for community, search, member data, form center, and content management
Communication between components using RPC/SOAP web services
Responsible for designing and implementing operations for around 25 Linux systems and networks

Jan 2001 - Feb 2006

5 years 2 months

Hamburg, Germany

Project Manager IT

Software

Design, implementation, and management of various projects in the finance sector based on Linux, Java EE, and Apple WebObjects

Jan 2000 - Dec 2001

2 years

Hamburg, Germany

Developer

Software

Design and implementation of a journalistic image database and marketplace

Skills

Skill Focus:

Devops
Continuous Delivery
Architecture
Cloud
Java
Spring Boot
Terraform
Kubernetes

Methodology/mindset:

Devops
Lean
Agile
Kanban
Scrum
Oo
Functional
Tdd
Bdd
Patterns

Architecture:

Humans
Microservices
Event Driven
Domain Driven
Layered
Mvc
C4

Infrastructure:

Cloud Native
Kubernetes
Openshift
Aws
Gcp
Azure
Linux
Containers
Docker
Serverless
Service Mesh
Istio
Traefik
Apigee
Vmware
Kvm

Protocols:

Rest
Openapi
Graphql
Rpc
Grpc

Platforms/languages:

Java
Clojure
Groovy
Go
Python
Javascript
Shell

Testing:

Postman/newman
Insomnia
Selenium
Junit
Mockito
Gherkin
Cucumber
Spock
Testcontainers
Property Based
K6
Litmuschaos

Ci/cd:

Gitops
Argocd
Flux
Github Actions
Azure Devops
Jenkins
Jenkins X
Ansible
Terraform
Maven
Gradle

Libraries/apis/sdks:

Spring
Grails
Jee
Alfresco
Bpmn
Jbpm
Activiti
Cmis

Databases:

Mysql
Postgresql
Oracle
Solr
Elasticsearch
Mongodb

Observability:

Prometheus
Grafana
Elk
Opentelemetry
Azure Application Insights
Gcp Monitoring
Aws Cloudwatch

Eventing/streaming:

Aws Sns/-sqs
Gcp Pubsub
Rabbitmq
Jms

Security:

Pki
Owasp
Zero Trust
Oauth2
Openid Connect
Saml
Tls
Waf
Gcp Cloud Armor

Mindset:

Trust Is The Foundation Of Psychological Safety And Is More Important Than Technology.
Culture Is The Framework Contract – "... Eats Strategy For Breakfast"
"We Shape Our Buildings; Thereafter They Shape Us"
One Team, One Goal
Change Is The Only Constant
Simplicity Matters
Learning Lasts A Lifetime

Highlights:

Discovery Of Devops Culture
Infrastructure As Code
Quantum Leap To Cloud Native
(Re-) Discovery Of Lisp (Clojure)
Founding Pink Gorilla – A Clojure(script)-based Notebook With Platform Ambitions