
Dean Cullen engineered and refined performance testing and configuration management solutions across the hmcts/cnp-flux-config, hmcts/cnp-plum-recipes-service, and hmcts/cnp-jenkins-library repositories. He delivered end-to-end performance validation by integrating Gatling load tests and Dynatrace monitoring into Jenkins-based CI/CD pipelines, enabling earlier detection of regressions and improved deployment reliability. Dean’s work included YAML-based policy updates, cron scheduling for migration workflows, and robust rollback procedures to ensure stability during experimentation. Using Groovy, Java, and YAML, he strengthened configuration management for secrets and environment variables, demonstrating a methodical approach to risk mitigation, traceability, and production-aligned testing in cloud infrastructure environments.
February 2026: Delivered end-to-end performance testing capabilities in the hmcts/cnp-jenkins-library pipeline, integrating Dynatrace monitoring, synthetic tests, and Gatling load tests into the build/deploy flow to enable performance validation during deployments. Strengthened configuration management for perf testing secrets and environment variables, and implemented perf test stages within the pipeline, supported by a DynatraceClient integration and updated DT endpoints. Executed targeted code improvements and bug fixes to stabilize the perf flow, including correcting pipeline variable naming and ensuring Java 17 compatibility via proper JAVA_HOME path handling. Business value: earlier performance feedback, reduced risk of regressions, and more reliable performance readiness signals across environments.
February 2026: Delivered end-to-end performance testing capabilities in the hmcts/cnp-jenkins-library pipeline, integrating Dynatrace monitoring, synthetic tests, and Gatling load tests into the build/deploy flow to enable performance validation during deployments. Strengthened configuration management for perf testing secrets and environment variables, and implemented perf test stages within the pipeline, supported by a DynatraceClient integration and updated DT endpoints. Executed targeted code improvements and bug fixes to stabilize the perf flow, including correcting pipeline variable naming and ensuring Java 17 compatibility via proper JAVA_HOME path handling. Business value: earlier performance feedback, reduced risk of regressions, and more reliable performance readiness signals across environments.
January 2026 summary for hmcts/cnp-plum-recipes-service focusing on delivering end-to-end performance validation in CI/CD and stabilizing pipeline configurations. Key features include enabling Gatling-based performance tests in Jenkins, configuring perf stages and paths, and aligning configurations with the infra branch. A coordinated revert streamlined misconfigurations, restoring stable integration with infrastructure changes.
January 2026 summary for hmcts/cnp-plum-recipes-service focusing on delivering end-to-end performance validation in CI/CD and stabilizing pipeline configurations. Key features include enabling Gatling-based performance tests in Jenkins, configuring perf stages and paths, and aligning configurations with the infra branch. A coordinated revert streamlined misconfigurations, restoring stable integration with infrastructure changes.
Monthly summary for 2025-11 (hmcts/cnp-flux-config). Focused on performance and test coverage enhancements for the DJF migration workflow. Delivered two major features with traceable commits: 1) Migration Task Scheduling and Performance Improvements (cron schedule tuning and increased migration case limit) and 2) Performance Testing Configuration and Image Filtering Policy Updates (perf test YAML updates, dummy perf flag, and expanded image filtering policies to cover broader production tags and new naming conventions). No major bugs fixed this month. Impact: improved migration throughput and reliability, safer and more realistic performance testing, and better alignment of image policies with production naming. Technologies demonstrated: cron scheduling, YAML-based configuration, performance testing orchestration, and image policy governance, with clear change traceability via commits.
Monthly summary for 2025-11 (hmcts/cnp-flux-config). Focused on performance and test coverage enhancements for the DJF migration workflow. Delivered two major features with traceable commits: 1) Migration Task Scheduling and Performance Improvements (cron schedule tuning and increased migration case limit) and 2) Performance Testing Configuration and Image Filtering Policy Updates (perf test YAML updates, dummy perf flag, and expanded image filtering policies to cover broader production tags and new naming conventions). No major bugs fixed this month. Impact: improved migration throughput and reliability, safer and more realistic performance testing, and better alignment of image policies with production naming. Technologies demonstrated: cron scheduling, YAML-based configuration, performance testing orchestration, and image policy governance, with clear change traceability via commits.
In Aug 2025 for hmcts/cnp-plum-recipes-service, the team explored performance testing capabilities by prototyping an integration with the infrastructure branch, enabling performance test stages and related environment configuration. The work established a traceable change path with commits for setup and for rollback. A subsequent revert removed the perftest changes and the configuration to minimize risk, restoring baseline and preserving stability. Overall, the month balanced experimental delivery with risk controls and laid groundwork for future performance testing efforts.
In Aug 2025 for hmcts/cnp-plum-recipes-service, the team explored performance testing capabilities by prototyping an integration with the infrastructure branch, enabling performance test stages and related environment configuration. The work established a traceable change path with commits for setup and for rollback. A subsequent revert removed the perftest changes and the configuration to minimize risk, restoring baseline and preserving stability. Overall, the month balanced experimental delivery with risk controls and laid groundwork for future performance testing efforts.
May 2025 monthly summary for hmcts/cnp-flux-config. Focused on stabilizing and simplifying image policy configuration to improve tag filtering and ordering for the prl-cos service, by removing a redundant policy entry from perftest-image-policy.yaml. The change is scoped, well-documented, and validated to reduce policy noise in performance testing pipelines.
May 2025 monthly summary for hmcts/cnp-flux-config. Focused on stabilizing and simplifying image policy configuration to improve tag filtering and ordering for the prl-cos service, by removing a redundant policy entry from perftest-image-policy.yaml. The change is scoped, well-documented, and validated to reduce policy noise in performance testing pipelines.

Overview of all repositories you've contributed to across your timeline