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Kornilios Kourtis

PROFILE

Kornilios Kourtis

Kornilios built and maintained core tracing, policy enforcement, and observability features in the cilium/tetragon repository, focusing on kernel-level event monitoring and runtime policy management. He engineered robust BPF and eBPF integrations, implemented BTF validation, and enhanced policy telemetry, enabling fine-grained tracing and actionable metrics. Using Go and C, Kornilios refactored critical components for reliability, optimized CI/CD workflows, and improved error handling and documentation. His work included compressed BPF object support, advanced selector parsing, and USDT/BTF tracing enhancements, resulting in scalable, maintainable code. The depth of his contributions addressed kernel compatibility, performance, and developer experience across complex system boundaries.

Overall Statistics

Feature vs Bugs

75%Features

Repository Contributions

183Total
Bugs
21
Commits
183
Features
64
Lines of code
22,786
Activity Months12

Work History

October 2025

6 Commits • 3 Features

Oct 1, 2025

October 2025 — cilium/tetragon: Focused on strengthening tracing reliability, expanding USDT testing and CI tooling, and improving documentation. Delivered detection of bpf_probe_write_user and integrated reporting into LogFeatures, expanded USDT tests for resolve/override with nested fields and u32 types, enhanced CI tooling to build BTF with pahole/llvm for usdt-resolve, added robust handling to prevent crashes when perf data is empty, and extended tracing policy docs to include BTF argument types (btfType, btfPath). These changes reduce crash risk, improve data accuracy, speed up troubleshooting, and empower engineers with clearer tracing configurations. Business value: more stable performance instrumentation, faster CI feedback, and clearer policy guidance for USDT usage.

September 2025

15 Commits • 3 Features

Sep 1, 2025

Sep 2025: Delivered policy telemetry and statistics, USDT/BTF tracing enhancements, and policy config/tooling improvements in cilium/tetragon. These workstreams improve observability, troubleshooting, and reliability, delivering measurable business value through actionable metrics, robust policy configuration, and enhanced tracing fidelity.

July 2025

16 Commits • 4 Features

Jul 1, 2025

2025-07 Monthly Summary — cilium/tetragon This month focused on strengthening the correctness, scalability, and maintainability of runtime tracing and BTF validation. Key features delivered, major bugs fixed, and business impact are summarized below. Key features delivered: - BTF Validation Improvements: added dentry type recognition, allowed void* for char_buf, corrected kernel_cap_t type handling, and broadened integer type compatibility checks. - CapabilitiesGained Tracing Enhancements: introduced CapabilitiesGained operator with API integration, CRD updates, kernel selector support, tests, and compatibility gating. - Tracing Policy Selectors Robustness and ArgSelector Refactor: refactored ArgSelector to support multiple arguments; improved selector processing for multiple selectors, including handling inactive selectors; updated docs/tests. - ExecveMapUpdater Relocation: moved ExecveMapUpdater to its own package for clearer structure and updated imports. Major bugs fixed: - BTF validation edge-case fixes (dentry type recognition, void* handling for char_buf, correct kernel_cap_t usage). - Robustness improvements for multiple/inactive tracing selectors (preventing misbehavior in complex selector configurations). Overall impact and Accomplishments: - Increased reliability of BPF program validation and kernel compatibility, reducing false positives and enabling broader kernel coverage. - Enabled richer, policy-driven runtime tracing with CapabilitiesGained, improving security and observability capabilities. - Improved code organization and maintainability through package-level relocation and refactoring. Technologies/Skills Demonstrated: - BTF and kernel-type handling, BPF concepts, Go-based operator patterns, CRDs, Kubernetes selectors, test-driven development, and codebase modularization.

June 2025

11 Commits • 6 Features

Jun 1, 2025

June 2025 monthly summary for cilium/tetragon focused on stabilizing and accelerating tracing-based workflows. Delivered a set of core reliability and performance improvements across tracing, kprobes, BTF validation, capability selectors, and program loading, with tangible business value through reduced noise, faster sensor readiness, and clearer diagnostics.

May 2025

12 Commits • 2 Features

May 1, 2025

Monthly summary for 2025-05 focusing on cilium/tetragon: delivered feature enhancements to reduce image size and support loading compressed BPF objects; centralized library detection with tetragon-info.json; robust path handling; Helm chart cleanup; and notable CI and tooling improvements that boosted stability and reliability. Key outcomes include improved startup reliability, reduced deployment footprint, and clearer configuration practices, supported by targeted commits across build, tetra and sensors components.

April 2025

7 Commits • 4 Features

Apr 1, 2025

April 2025 monthly summary for cilium/tetragon: Delivered targeted enhancements across documentation, build/CI, API event checking, and performance. Resulted in clearer deployment guidance, faster sensor startup, and stronger runtime validation. Strengthened security and observability through API extensions and improved error reporting, with CI tooling built prior to linting to ensure stable, reproducible checks.

March 2025

13 Commits • 5 Features

Mar 1, 2025

March 2025 highlights in cilium/tetragon: deprecated FollowFD/UnfollowFD/CopyFD actions across Tetragon with CRD notices and planned removal in v1.5; improved BPF processing with reduced stack usage and a fix for verification on older kernels (5.4); enhanced metrics and reliability (syscall metrics type-based, extended tetra operation timeout to 30s, refined Helm runtime hook arguments, and a corrected install/kubernetes typo); release engineering and CRD upgrades (prep for v1.4.0, Renovate config updates for Go modules, and CRD schema version bumped to 1.5.0); and test infrastructure improvements to reuse existing gRPC connections and ensure proper cleanup. These changes reduce maintenance burden, improve kernel compatibility and observability, and accelerate delivery of user-visible value.

February 2025

38 Commits • 10 Features

Feb 1, 2025

February 2025 highlights: Shipped end-to-end tracing policy mode infrastructure (policyInfo, policy_conf, TracingPolicyMode) with gRPC exposure and CLI/API codegen adjustments; introduced policy metrics for CRI resolution and wrappers to enable/disable policy in sensors. Delivered Tetra/tp refinements with ConfigureTracingPolicy integration and set-mode command, plus gRPC tracing policy configuration and protogen tooling updates. Enhanced quality and maintainability: policy handle uprobes fix, deprecated code removal in gRPC, removal of enable/disable TracingPolicy in Sensors, and getevents --reconnect option. Strengthened testing and docs: policy mode tests, policy enforcement mode documentation, tester utilities, and weekly CI scheduling for little-vm-helper-images.

January 2025

8 Commits • 2 Features

Jan 1, 2025

January 2025 monthly summary for cilium/tetragon. Focused on improving contributor experience, stabilizing CI, and hardening test/server reliability to support scalable development and faster feedback loops. Key outcomes include documentation hygiene, CI determinism, and robust cleanup practices that reduce flaky behavior and unblock contributor workflows.

December 2024

20 Commits • 4 Features

Dec 1, 2024

December 2024 monthly summary for cilium/tetragon focusing on reliability, observability, and release readiness. Delivered robust CGTracker testing infrastructure with deeper tracing integration, improved policy validation under nested cgroups, and enhanced test tooling. Fixed a subtle mb_bitset handling bug that preserved matching across chained executions. Introduced BPF error metrics for improved debugging and observability, with tooling and preprocessing support. Strengthened release workflows and CI coverage, and added performance-focused utilities to quantify events in tests.

November 2024

33 Commits • 20 Features

Nov 1, 2024

November 2024 focused on delivering the CGTracker core features within tetragon, expanding security posture, improving testability and reliability, and laying groundwork for pod-aware telemetry. Key features shipped, major fixes applied, and core refactors completed to boost stability, security, and operational efficiency. This month also yielded improvements in observability and developer productivity through log/noise reduction and cleaner initialization flows.

October 2024

4 Commits • 1 Features

Oct 1, 2024

October 2024: Delivered targeted features, fixed API correctness, and stabilized CI across cilium/tetragon and cilium/little-vm-helper-images. Key outcomes include removing the beta designation from the policy filter, correcting the BPF API header to include ancestor_level, and reducing CI flakiness by skipping ARM E2E label tests; plus migrating CI to GitHub native arm64 runners to maintain ARM build continuity. These efforts reduce misconfiguration risk, speed up PR validation, and improve cross-architecture reliability.

Activity

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Quality Metrics

Correctness92.4%
Maintainability91.8%
Architecture90.0%
Performance85.8%
AI Usage20.0%

Skills & Technologies

Programming Languages

BPFCDockerfileGoJSONJSON5MakefileMarkdownProtocol BuffersShell

Technical Skills

API DesignAPI DevelopmentAPI MigrationAPI RefactoringBPFBTF ValidationBackend DevelopmentBug FixingBuild SystemBuild SystemsCC DevelopmentCI/CDCLI DevelopmentCRD Development

Repositories Contributed To

2 repos

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

cilium/tetragon

Oct 2024 Oct 2025
12 Months active

Languages Used

CGoYAMLBPFMakefilebashJSON5Markdown

Technical Skills

BPFCI/CDConfiguration ManagementDocumentationEnd-to-End TestingGo

cilium/little-vm-helper-images

Oct 2024 Feb 2025
2 Months active

Languages Used

YAML

Technical Skills

CI/CDGitHub ActionsWorkflow Automation

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