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Stefan Eissing

PROFILE

Stefan Eissing

Over 15 months, this developer enhanced the apache/httpd repository by building and maintaining core features for HTTP/2 and certificate automation modules. They delivered robust improvements in mod_md and mod_http2, focusing on reliability, security, and performance through C programming, Python scripting, and Apache configuration. Their work included implementing ACME protocol enhancements, optimizing memory management, and refining error handling and logging. They addressed cross-version compatibility, stabilized CI pipelines, and improved documentation for user onboarding and configuration clarity. By fixing critical bugs and introducing targeted features, they ensured smoother deployments, reduced operational risk, and maintained alignment with evolving standards in web server development.

Overall Statistics

Feature vs Bugs

45%Features

Repository Contributions

40Total
Bugs
17
Commits
40
Features
14
Lines of code
1,158,975
Activity Months15

Your Network

732 people

Shared Repositories

17
Eric CovenerMember
Daniel FerradalMember
Giovanni BechisMember
Vincent DeffontainesMember
Giannis ChristodoulouMember
Ivan ZhakovMember
Christophe JailletMember
Jean-Frederic ClereMember
Jim JagielskiMember

Work History

May 2026

2 Commits • 1 Features

May 1, 2026

May 2026 monthly summary for apache/httpd highlights two focused contributions: a critical stability/security fix in the HTTP/2 proxy link mapping and a modernization of the Python test configuration to align with current standards. Delivered via two commits, these changes reduce risk in production deployments and improve CI reliability.

April 2026

3 Commits • 1 Features

Apr 1, 2026

April 2026 (apache/httpd): Focused on Mod_md reliability, onboarding UX, and versioning discipline. Delivered user-centric improvements for ACME/Terms of Service, standardized versioning, and strengthened renewal integrity, contributing to reduced risk and clearer release management.

February 2026

3 Commits • 1 Features

Feb 1, 2026

February 2026: Focused on stability, compatibility, and maintainability for apache/httpd. Delivered HTTP/2 stability upgrades and memory allocator deprecation to improve third-party module reliability, and fixed ARI-related ACME order behavior and APR compatibility to ensure robust ACME automation across versions. These changes reduce memory-related incidents, improve cross-version interoperability, and align with upstream modules.

December 2025

3 Commits • 1 Features

Dec 1, 2025

December 2025 — Apache httpd: Key features delivered, major fixes, and impact focused on reliability, configuration correctness, and memory safety in core modules (mod_md and mod_http2).

November 2025

4 Commits • 2 Features

Nov 1, 2025

November 2025 — Apache httpd: Focused on delivering security, stability, and performance improvements through targeted feature updates and memory/HTTP handling fixes. Key features delivered include Mod_md certificate management enhancements (v2.6.5) with a new initial certificate check delay directive and strengthened renewal security, and HTTP/2 header processing improvements that leverage nghttp2-provided trailer lengths and a refactor of header-name comparisons for accuracy and speed. Major bug fix addressed a memory leak in OpenSSL BIGNUMs and improved curl handle reuse in the Mod_md workflow (v2.6.6). Impact: higher security posture for TLS certificate lifecycle, reduced memory footprint and resource churn, and faster, more reliable HTTP/2 header processing under load. Technologies demonstrated: TLS/certificate automation (mod_md), OpenSSL memory management, curl handle lifecycle, nghttp2 integration, and performance-focused C refactoring (ap_cstr_casecmpn).

September 2025

1 Commits

Sep 1, 2025

Month: 2025-09 — Apache httpd (mod_md) monthly review focused on robustness and compatibility improvements in string handling, plus targeted bug fix and alignment with the mod_md GitHub repository.

August 2025

6 Commits • 3 Features

Aug 1, 2025

August 2025 performance overview for apache/httpd: Delivered robust HTTP/2 error handling enhancements, advanced mod_md 2.6.x renewal features (ACME ARI support, adjusted retry logic, and Tailscale removal), improved build/documentation traceability, and completed critical bug fixes. These changes improve reliability, reduce renewal traffic bursts, and streamline release processes.

July 2025

1 Commits

Jul 1, 2025

July 2025: Focused bug fix in HTTP/2 log2 calculations across httpd's HTTP/2 modules to stabilize push diaries and proxy window sizing. Implemented unsigned integer handling in log2 paths to prevent incorrect sizing, improving reliability of HTTP/2 proxying and push operations.

June 2025

1 Commits

Jun 1, 2025

June 2025 — Apache httpd (mod_md) documentation fix delivered. Key features delivered: Documentation restoration of the MDActivationDelay directive in mod_md to fill a gap in user-facing configuration guidance. Major bugs fixed: Restored the MDActivationDelay directive documentation to address missing guidance. Overall impact and accomplishments: Improves configuration reliability for mod_md users, reduces ambiguity, and supports smoother adoption; maintains alignment with module capabilities and documentation standards. Technologies/skills demonstrated: Git-based version control, focused documentation work, mod_md configuration semantics, Apache httpd module ecosystem, cross-repo documentation alignment.

May 2025

2 Commits

May 1, 2025

May 2025 focused on stabilizing core HTTP and MD features for apache/httpd through targeted fixes that boost reliability, performance, and security. Key work includes correcting H2WindowSize handling and session/multiplexing logic for HTTP/2, and enhancing TLS-ALPN-01 challenge support and status output formatting in MD, with related version upgrades. These changes reduce risk of incorrect window sizing, improve multiplexing efficiency, support multiple MDPrivateKeys (EC and RSA), and fix status page clarity. Overall, the month delivered measurable improvements in connection throughput, TLS challenge reliability, and operator UX, enabling smoother deployments and fewer incidents.

March 2025

6 Commits • 1 Features

Mar 1, 2025

March 2025 monthly summary for apache/httpd focusing on HTTP/2 features, reliability, and maintenance. Delivered key HTTP/2 robustness and configurability improvements via mod_md 2.0.30, including improved header handling, timeout behavior, and a new H2MaxHeaderBlockLen directive. Implemented HTTP/2 reliability fixes such as correct 304 handling from mod_cache, restoration of stable backend detection in mod_proxy_http2, and enhanced logging for HTTP/2 session errors. Completed maintenance tasks to increment the versioning counter and fix documentation typos to reflect mod_http2 2.0.30. These changes collectively improve performance, reliability, observability, and release accuracy, delivering tangible business value by reducing client hangs, stabilizing backend interactions, and improving deployability.

February 2025

2 Commits • 2 Features

Feb 1, 2025

February 2025 monthly summary for apache/httpd development focused on delivering observable improvements in security, reliability, and performance through targeted feature work and bug fixes. Implemented enhanced ACME-based certificate management via Mod_md and added robust per-request timing in HTTP/2 for better performance visibility.

January 2025

2 Commits • 1 Features

Jan 1, 2025

January 2025 (apache/httpd): Implemented reliability enhancements for certificate issuance (mod_md) and stabilized HTTP/2 test behavior. This work improves domain verification resilience, observability during certificate orders, and test reliability across curl versions, lowering incident risk and accelerating debugging and deployments.

December 2024

3 Commits • 1 Features

Dec 1, 2024

December 2024 monthly summary for apache/httpd. Focused on stabilizing the test suite, delivering a quality Mod_md 2.4.29 release, and improving operational visibility. Achievements centered on reducing CI flakiness, ensuring robust HTTP-01 handling, and polishing server-status and OCSP logging.

November 2024

1 Commits

Nov 1, 2024

Month: 2024-11 — Stabilized Mod_http2 behavior under reset scenarios in apache/httpd. Implemented a keepalive timeout fix for reset requests, adding logic to count failed RST'ed requests to ensure connections honor the keepalive timeout after an initial request failure. Included regression tests validating the fix. This work improves reliability of persistent connections and reduces dropped requests under reset traffic, contributing to better user experience in high-load scenarios.

Activity

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Quality Metrics

Correctness92.0%
Maintainability89.2%
Architecture88.6%
Performance84.6%
AI Usage20.0%

Skills & Technologies

Programming Languages

Apache ConfigurationCMarkdownPythonTextXMLYAML

Technical Skills

ACME ProtocolACME protocolApache HTTP ServerApache HTTP Server Module DevelopmentApache HTTP Server module developmentApache configurationApache module developmentApache modulesAutomationBackend DevelopmentBug FixingC ProgrammingC programmingCachingCertificate Management

Repositories Contributed To

1 repo

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

apache/httpd

Nov 2024 May 2026
15 Months active

Languages Used

CPythonTextApache ConfigurationMarkdownXMLYAML

Technical Skills

HTTP/2Network ProtocolsServer ConfigurationTestingACME protocolApache HTTP Server Module Development