Event-Driven Digital Transformation Platform with Kubernetes & Drools
Cloud-Native Automation for Germany's Leading Energy Service Provider
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Energy Services Platform
Energy services operations center with Kubernetes orchestration dashboards
The Challenge
Complete Digital Transformation with Event-Driven Process Automation
This leading European energy services provider required a comprehensive digital transformation of their backend systems to automate complex business processes. The goal was to migrate legacy systems to a modern Kubernetes platform with event-driven architecture supporting millions of energy metering transactions.
Legacy systems unable to handle growing business process automation requirements
Complex business logic scattered across multiple systems requiring centralization
Need for guaranteed message ordering across distributed microservices
Integration of new CRM system (BSI CRM) with existing SAP and core systems
Migration of entire tech stack to Kubernetes while maintaining no customer-visible downtime in this project
Separation of business rules from application code for independent testing and deployment
The Solution
Modern Event-Driven Platform with Drools Rules Engine on Kubernetes
As Lead Developer and Architect, I designed and implemented a complete cloud-native event-driven platform on Kubernetes (AKS). The architecture separates business logic into a Drools rules engine, enabling independent development and testing of business rules while maintaining a highly scalable microservices architecture.
Event-Driven Core
CloudEvents-based architecture with Kafka/Azure Service Bus ensuring guaranteed message ordering per business case (Gevo)
Business Rules Engine
Drools rules stored as artifacts in Nexus, loaded dynamically by Rules Execution Service for decoupled business logic
Data Access Layer
GraphQL abstraction layer for read access to SAP and core systems, with event-driven writes to central PostgreSQL/Azure SQL data store
Process Management Integration
BSI CRM integrated via Graal Polyglot into Kubernetes stack with seamless event processing
GitOps Deployment
Complete GitFlow with Semantic Release, Renovate dependency updates, and ArgoCD-based Kustomize deployments
Critical Challenges
Key technical hurdles and how they were overcome
BSI CRM Integration with Soft Workflow Transition
Problem
Existing digital sales channel was highly efficient with well-established processes. New BSI CRM must become the leading system without disrupting running business operations. Old stack states must seamlessly adapt to BSI CRM workflows without losing transaction data or breaking customer experience.
Solution
Implemented sophisticated Drools workflow engine with custom business rules and state-holder database. Incoming orders are driven by Drools rules that determine if BSI CRM needs update, event trigger, or automated entity creation. Each state change handled by rules, orders automated through workflow aligned to business logic. Operator intervention only needed occasionally for edge cases - majority fully automated.
Migrated active order processing to new CRM without losing a single transaction - business didn't notice the switch
Impact
Extremely smooth system integration that worked as expected with nearly zero issues. No transaction data lost, customer experience seamless, business operations uninterrupted.
Legacy Stack → Kubernetes Migration Without Downtime
Problem
Complete transformation of the digital sales and CRM infrastructure needed while maintaining no customer-visible downtime for lead and order workflows. Legacy systems, BSI CRM and the Enterprise Integration Platform are deeply intertwined with business operations, making migration extremely risky.
Solution
Gradual service extraction with parallel operation strategy - old and new systems running side by side. Automated GitOps deployment with comprehensive testing at every stage. Traffic gradually shifted from legacy to Kubernetes with rollback capability at each step.
Final legacy service decommissioned after months of parallel operation - zero incidents throughout entire migration
Impact
100% stack migrated to Kubernetes with zero service disruption. No customer-facing outages, no data loss, seamless transition invisible to end users.
Business Impact
Measurable value delivered to the business
Operational Efficiency
Employee hours saved through automated business processes via Drools rules engine, freeing staff for higher-value work
Infrastructure Cost
Cloud costs halved via GraalVM Native (90% memory reduction) and efficient KEDA-based auto-scaling
Time to Market
New features deployed in 15 minutes vs. 4 hours through GitOps automation with Renovate and ArgoCD
Developer Productivity
GitOps automation freed development team from operational tasks, enabling focus on feature development and innovation
Innovations
Groundbreaking solutions that set new standards
Drools Rules Engine with Dynamic Artifact Loading
Business rules stored as versioned artifacts in Nexus repository, loaded dynamically by Rules Execution Service. Enables independent development, testing, and deployment of business logic without application redeployment.
First major energy services company to decouple business logic into separate artifact lifecycle, enabling business analysts to update rules without developer involvement
Impact: 80% process automation, rules updated in minutes vs. days, business agility dramatically improved
GraphQL Abstraction for Legacy Integration
Unified GraphQL layer providing read access to SAP and core systems, with event-driven writes ensuring eventual consistency. Shields modern services from legacy complexity while maintaining data integrity.
Novel hybrid approach combining GraphQL reads with event-driven writes for legacy integration without coupling
Impact: Simplified integration by 70%, enabled rapid development of new services without understanding legacy systems
Multi-Architecture Container Strategy
Automated JIB builds generating both JVM and GraalVM Native images. Development and testing on JVM (faster builds), production on Native (90% memory reduction, 300x startup speed).
Pioneered dual-architecture strategy in energy sector - developer experience + production efficiency
Impact: Best of both worlds: 50% cloud cost reduction while maintaining developer productivity
GitOps with Renovate Automation
Complete GitOps workflow with Renovate automatically creating PRs for dependency updates across test/release/prod. Semantic Release handles versioning. ArgoCD deploys via Kustomize remote bases.
Fully automated dependency management with environment-aware promotion - zero manual intervention
Impact: 90% faster deployments, security patches applied within hours, zero deployment-related incidents
"The event-driven platform has revolutionized our business process automation. The decoupled Drools rules engine allows us to update business logic independently, and the full GitOps workflow has dramatically improved our deployment confidence."
Technologies Used
core
persistence
messaging
infrastructure
devops
monitoring
integration
additional
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