microsoft/hcsshim
Oct 2024 – Jun 2026
15 Months active
Languages Used
XMLGoYAMLMarkdown
Technical Skills
System ProgrammingWindows DevelopmentCI/CDCode CleanupGoConfiguration Management
Maksim An
PROFILE
Maksim An
Over 15 months, contributed to microsoft/hcsshim by building and refining core features for Windows and Linux container infrastructure. Delivered enhancements such as resource partitioning, confidential container security, and extensible storage, while improving reliability through targeted bug fixes and robust error handling. Leveraged Go, YAML, and Windows API to implement container lifecycle management, CI/CD automation, and DLL compatibility for image creation and verification. Focused on maintainability by refactoring code, aligning policy enforcement, and strengthening observability with detailed logging and diagnostics. The work emphasized stability, security, and test coverage, supporting multi-tenant virtualization and streamlined development workflows across cloud and hybrid environments.
Overall Statistics
Feature vs Bugs
70%Features
Repository Contributions
32Total
Bugs
7
Commits
32
Features
16
Lines of code
55,620
Activity Months15
Your Network
4963 peopleSame Organization
@microsoft.com4939
GitOpsMember
Ananta GuptaMember
Abi GicicMember
Abigail HartmanMember
Abram SandersonMember
Adam EttenbergerMember
Adam KrantzMember
Alexandre GattikerMember
Ami HollanderMember
Shared Repositories
24
Work History
June 2026
12 Commits • 2 Features
Jun 1, 2026June 2026: Strengthened security and reliability for confidential containers in microsoft/hcsshim. Delivered unified security policy handling with SNP attestation and DM-verity support, enhanced WCOW/LCOW workflows, and debug modes for confidential Windows/WCOW. Improved container lifecycle with explicit states and overlay path normalization, added regression tests. Fixed critical resource leaks and reset handling in wclayer, and hardened cleanup paths. Marked gcs-sidecar as a critical process to prevent inconsistent UVM states. Added AMD SNP PSP API DLL staging into container security-context and boot-files/diagnostics enhancements for better observability. Demonstrated Go, security policy tooling, UVM integration, and CI-tested delivery.
12 Commits • 2 Features
Jun 1, 2026June 2026: Strengthened security and reliability for confidential containers in microsoft/hcsshim. Delivered unified security policy handling with SNP attestation and DM-verity support, enhanced WCOW/LCOW workflows, and debug modes for confidential Windows/WCOW. Improved container lifecycle with explicit states and overlay path normalization, added regression tests. Fixed critical resource leaks and reset handling in wclayer, and hardened cleanup paths. Marked gcs-sidecar as a critical process to prevent inconsistent UVM states. Added AMD SNP PSP API DLL staging into container security-context and boot-files/diagnostics enhancements for better observability. Demonstrated Go, security policy tooling, UVM integration, and CI-tested delivery.
June 2026
May 2026
1 Commits • 1 Features
May 1, 2026Monthly work summary for 2026-05 focusing on delivering ResourcePartitionId support in the microsoft/hcsshim repository. Key outcomes included adding ResourcePartitionId to the VirtualMachine schema, plumbed into HCS docs for LCOW and WCOW create paths, refactoring the builder to parse resource partition options, and adding tests to validate proper handling. These changes improve resource isolation, allow finer-grained VM resource allocation, and enhance overall architecture and test coverage.
May 2026
1 Commits • 1 Features
May 1, 2026Monthly work summary for 2026-05 focusing on delivering ResourcePartitionId support in the microsoft/hcsshim repository. Key outcomes included adding ResourcePartitionId to the VirtualMachine schema, plumbed into HCS docs for LCOW and WCOW create paths, refactoring the builder to parse resource partition options, and adding tests to validate proper handling. These changes improve resource isolation, allow finer-grained VM resource allocation, and enhance overall architecture and test coverage.
April 2026
1 Commits • 1 Features
Apr 1, 2026April 2026 monthly summary for microsoft/hcsshim, focusing on feature delivery, observability improvements, and the resulting business value for Windows container execution environments.
1 Commits • 1 Features
Apr 1, 2026April 2026 monthly summary for microsoft/hcsshim, focusing on feature delivery, observability improvements, and the resulting business value for Windows container execution environments.
April 2026
March 2026
2 Commits • 1 Features
Mar 1, 2026March 2026 (microsoft/hcsshim) delivered a stronger image integrity workflow and improved GCS sidecar reliability. Key changes include a CimGetVerificationInformation-based image verification enhancement and a security policy fragment handling bug fix in the GCS sidecar, accompanied by comprehensive unit tests. These updates improved security, reliability, and developer velocity across the container image lifecycle and RPC communication with the shim.
March 2026
2 Commits • 1 Features
Mar 1, 2026March 2026 (microsoft/hcsshim) delivered a stronger image integrity workflow and improved GCS sidecar reliability. Key changes include a CimGetVerificationInformation-based image verification enhancement and a security policy fragment handling bug fix in the GCS sidecar, accompanied by comprehensive unit tests. These updates improved security, reliability, and developer velocity across the container image lifecycle and RPC communication with the shim.
February 2026
1 Commits • 1 Features
Feb 1, 2026February 2026 monthly summary for microsoft/hcsshim focusing on the CIM DLL compatibility and write-path optimization effort, including observability enhancements and test improvements.
1 Commits • 1 Features
Feb 1, 2026February 2026 monthly summary for microsoft/hcsshim focusing on the CIM DLL compatibility and write-path optimization effort, including observability enhancements and test improvements.
February 2026
December 2025
2 Commits • 2 Features
Dec 1, 2025December 2025 monthly summary for microsoft/hcsshim focusing on storage and filesystem reliability enhancements. Key outcomes include enabling extensible storage for Linux containers on Windows and strengthening CIMFS image creation reliability across builds.
December 2025
2 Commits • 2 Features
Dec 1, 2025December 2025 monthly summary for microsoft/hcsshim focusing on storage and filesystem reliability enhancements. Key outcomes include enabling extensible storage for Linux containers on Windows and strengthening CIMFS image creation reliability across builds.
November 2025
1 Commits • 1 Features
Nov 1, 2025November 2025 performance summary for microsoft/hcsshim. Focused on stabilizing the gcs-sidecar component and strengthening CI validation. Delivered a new CI build step for gcs-sidecar and resolved import issues in internal/gcs-sidecar/host.go, improving build reliability and readiness for production deployments. These efforts reduced CI noise, accelerated feedback loops, and demonstrated effective Go development, CI/CD discipline, and code health improvements.
1 Commits • 1 Features
Nov 1, 2025November 2025 performance summary for microsoft/hcsshim. Focused on stabilizing the gcs-sidecar component and strengthening CI validation. Delivered a new CI build step for gcs-sidecar and resolved import issues in internal/gcs-sidecar/host.go, improving build reliability and readiness for production deployments. These efforts reduced CI noise, accelerated feedback loops, and demonstrated effective Go development, CI/CD discipline, and code health improvements.
November 2025
October 2025
1 Commits
Oct 1, 2025October 2025 monthly summary for microsoft/hcsshim focused on container signaling reliability and stability. Key accomplishment: delivered a targeted bug fix that confines signals to the container's init process, reordered signal policy enforcement, and switched to using process.Kill instead of ShutdownContainer to prevent unintended container shutdowns. Impact includes reduced risk of production outages and clearer signaling semantics across container lifecycles.
October 2025
1 Commits
Oct 1, 2025October 2025 monthly summary for microsoft/hcsshim focused on container signaling reliability and stability. Key accomplishment: delivered a targeted bug fix that confines signals to the container's init process, reordered signal policy enforcement, and switched to using process.Kill instead of ShutdownContainer to prevent unintended container shutdowns. Impact includes reduced risk of production outages and clearer signaling semantics across container lifecycles.
September 2025
2 Commits • 1 Features
Sep 1, 2025September 2025 monthly summary for microsoft/hcsshim: Delivered core improvements to resource isolation and reliability, aligning with platform stability and multi-tenant support goals. Key features include Resource Partitions with GUIDs and validation that ensures a GUID is assigned to a UVM and prevents simultaneous setting of resource_partition_id and cpu_group_id, with updated documentation and user-facing error messages. This enhances resource management accuracy and prevents conflicts in complex virtualization workloads. Major fixes include Hvsocket robustness—closed handles on DeviceIoControl failure to prevent resource leaks and improved HCSID handling by exiting with an error for invalid HCSID, strengthening error reporting and robustness. Impact: increased stability and predictability of resource allocation, reduced error-prone states, and clearer debugging paths for operators. Technologies demonstrated: Go-based subsystem development, DeviceIoControl integration, hvsocket/resource lifecycle management, validation patterns, and documentation practices.
2 Commits • 1 Features
Sep 1, 2025September 2025 monthly summary for microsoft/hcsshim: Delivered core improvements to resource isolation and reliability, aligning with platform stability and multi-tenant support goals. Key features include Resource Partitions with GUIDs and validation that ensures a GUID is assigned to a UVM and prevents simultaneous setting of resource_partition_id and cpu_group_id, with updated documentation and user-facing error messages. This enhances resource management accuracy and prevents conflicts in complex virtualization workloads. Major fixes include Hvsocket robustness—closed handles on DeviceIoControl failure to prevent resource leaks and improved HCSID handling by exiting with an error for invalid HCSID, strengthening error reporting and robustness. Impact: increased stability and predictability of resource allocation, reduced error-prone states, and clearer debugging paths for operators. Technologies demonstrated: Go-based subsystem development, DeviceIoControl integration, hvsocket/resource lifecycle management, validation patterns, and documentation practices.
September 2025
July 2025
2 Commits • 1 Features
Jul 1, 2025July 2025: Focused stability and diagnosability improvements for microsoft/hcsshim. Delivered two impactful changes: (1) Kernel panic fix for LCOW with virtio-vsock by disabling virtio_vsock_init to ensure hv_sock transport, preventing panics in LCOW environments; no-op on kernels without virtio-vsock. (2) Enhanced error logging for mkfs.ext4 in CreateScratch, capturing mkfs.ext4 stderr alongside the error to provide richer debugging context for scratch formatting failures. These changes reduce production incidents, shorten triage time, and improve reliability of LCOW-based workflows. Commits tracked: 914512d9db1f87fb212f72767fdd3eb8abb7f85f and 1c0e46403dc04e0a1ffa4cc85cdd745992d256f3.
July 2025
2 Commits • 1 Features
Jul 1, 2025July 2025: Focused stability and diagnosability improvements for microsoft/hcsshim. Delivered two impactful changes: (1) Kernel panic fix for LCOW with virtio-vsock by disabling virtio_vsock_init to ensure hv_sock transport, preventing panics in LCOW environments; no-op on kernels without virtio-vsock. (2) Enhanced error logging for mkfs.ext4 in CreateScratch, capturing mkfs.ext4 stderr alongside the error to provide richer debugging context for scratch formatting failures. These changes reduce production incidents, shorten triage time, and improve reliability of LCOW-based workflows. Commits tracked: 914512d9db1f87fb212f72767fdd3eb8abb7f85f and 1c0e46403dc04e0a1ffa4cc85cdd745992d256f3.
April 2025
2 Commits • 1 Features
Apr 1, 2025April 2025 monthly summary for microsoft/hcsshim. Focused on delivering a privileged tooling improvement and aligning user parsing with the GCS policy system, with targeted refactoring to improve maintainability and consistency across policy enforcement components.
2 Commits • 1 Features
Apr 1, 2025April 2025 monthly summary for microsoft/hcsshim. Focused on delivering a privileged tooling improvement and aligning user parsing with the GCS policy system, with targeted refactoring to improve maintainability and consistency across policy enforcement components.
April 2025
March 2025
1 Commits • 1 Features
Mar 1, 2025March 2025 monthly summary for microsoft/hcsshim. Implemented HvSocket container connectivity with VMID-based addressing for WCOW UVM integration, enabling host applications to connect to containers via VMID. Introduced hvsocketaddr.exe for VMID generation and extended HCS schema with SystemGUID. Established AddressInfo mapping to route HvSocket traffic into the UVM, solidifying the WCOW-UVM integration. This work is tied to commit 62ddb129f044a01c4938e64c741ba243fea89fc6 (HvSocket support for containers #2353).
March 2025
1 Commits • 1 Features
Mar 1, 2025March 2025 monthly summary for microsoft/hcsshim. Implemented HvSocket container connectivity with VMID-based addressing for WCOW UVM integration, enabling host applications to connect to containers via VMID. Introduced hvsocketaddr.exe for VMID generation and extended HCS schema with SystemGUID. Established AddressInfo mapping to route HvSocket traffic into the UVM, solidifying the WCOW-UVM integration. This work is tied to commit 62ddb129f044a01c4938e64c741ba243fea89fc6 (HvSocket support for containers #2353).
February 2025
2 Commits • 1 Features
Feb 1, 2025February 2025 monthly summary for microsoft/hcsshim: CI Linting Improvements (GolangCI-Lint) delivered to strengthen code quality, reliability, and toolchain compatibility across modules. Upgraded linting action to golangci-lint v1.64, refined configurations (removed skip-dirs, improved error handling), and corrected ST1003 reporting by fixing Text to text. No major bug fixes this month; focus was on lint reliability and CI health, reducing noise and accelerating feedback.
2 Commits • 1 Features
Feb 1, 2025February 2025 monthly summary for microsoft/hcsshim: CI Linting Improvements (GolangCI-Lint) delivered to strengthen code quality, reliability, and toolchain compatibility across modules. Upgraded linting action to golangci-lint v1.64, refined configurations (removed skip-dirs, improved error handling), and corrected ST1003 reporting by fixing Text to text. No major bug fixes this month; focus was on lint reliability and CI health, reducing noise and accelerating feedback.
February 2025
November 2024
1 Commits • 1 Features
Nov 1, 2024November 2024 monthly summary for microsoft/hcsshim focused on removing deprecated features and simplifying CI/CD configurations to streamline maintenance and releases. The effort reduces technical debt and clarifies the codebase for future development and faster iterations.
November 2024
1 Commits • 1 Features
Nov 1, 2024November 2024 monthly summary for microsoft/hcsshim focused on removing deprecated features and simplifying CI/CD configurations to streamline maintenance and releases. The effort reduces technical debt and clarifies the codebase for future development and faster iterations.
October 2024
1 Commits • 1 Features
Oct 1, 2024Month: 2024-10. Concise monthly performance summary focusing on key developer accomplishments for microsoft/hcsshim, with emphasis on business value and technical achievements.
1 Commits • 1 Features
Oct 1, 2024Month: 2024-10. Concise monthly performance summary focusing on key developer accomplishments for microsoft/hcsshim, with emphasis on business value and technical achievements.
October 2024
Activity
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Quality Metrics
Correctness91.0%
Maintainability84.4%
Architecture84.8%
Performance79.6%
AI Usage31.8%
Skills & Technologies
Programming Languages
GoMarkdownXMLYAML
Technical Skills
API developmentCI/CDCloud InfrastructureCode CleanupConfiguration ManagementContainerizationDLL ManagementError HandlingGoGo DevelopmentGo TestingGo programmingKernel DevelopmentLintingLinux
Repositories Contributed To
Overview of all repositories you've contributed to across your timeline