Chris Smith

This commit introduces **new OpenTelemetry tracing capabilities** to the `auth` package's **gRPC and HTTP transport layers**. It enables `grpctransport` and `httptransport` to **inject static attributes**, **capture dynamic attributes from context**, and **enforce consistent error semantics** within OpenTelemetry spans. This **feature enhancement** adds `addOpenTelemetryStatsHandler` for gRPC and `addOpenTelemetryTransport` for HTTP, along with an internal `auth/internal/transport` module to manage known telemetry keys. The change significantly improves **observability and debugging** for authentication-related network requests by providing detailed, standardized tracing information, supported by comprehensive test cases for various scenarios.

This commit **fixes** an issue in the **`apidiff` workflow** within the **`.github` CI/CD configuration** to ensure proper detection of **breaking changes** in **GA (Generally Available) API packages**. Previously, the build might not fail for breaking changes in GA packages nested within non-versioned modules; now, the workflow explicitly scans for `apiv` patterns (e.g., `apiv1/`) in both the module path and the diff content. This **maintenance update** to `apidiff.yml` prevents unintended API regressions by ensuring the build correctly fails when such breaking changes are introduced, thereby safeguarding **API stability** for GA components.

This commit introduces a **new capability** to the **authentication package**, enabling enhanced observability for internal client communications. It adds a `TelemetryAttributes` field to the `InternalOptions` struct in both `auth/grpctransport/grpctransport.go` and `auth/httptransport/httptransport.go`. This **feature addition** allows internal gRPC and HTTP clients to specify **OpenTelemetry attributes**, providing more granular diagnostic information for internal service interactions.

This commit delivers a **bug fix** to the **authentication module's gRPC transport layer**, specifically addressing an issue with OpenTelemetry integration. It **removes a problematic singleton pattern** previously used for the OpenTelemetry stats handler within `auth/grpctransport/grpctransport.go`. The `addOpenTelemetryStatsHandler` function now **directly instantiates the `otelgrpc.clientHandler`**, restoring its intended normal usage and resolving potential conflicts or incorrect state management. This ensures **correct and reliable OpenTelemetry tracing and metrics** for gRPC calls processed by the authentication subsystem.

This commit **adds unit tests** to validate the **OpenTelemetry span generation and attribute population** within the **authentication (auth)** module. Specifically, new tests are introduced for both the `grpctransport` and `httptransport` layers, ensuring that tracing for authentication operations is correctly implemented. This **maintenance** work improves the reliability and observability of the authentication service by verifying its OpenTelemetry integration, ensuring accurate telemetry data for debugging and monitoring.

This commit introduces **new, type-safe methods** for loading credentials and ID tokens from files and JSON within the **`auth` module**. It **deprecates existing unsafe options** in `credentials.DetectOptions` and `idtoken.Options`, guiding users towards more secure practices. A significant **refactoring** replaces internal integer-based credential type identification with public string-based constants, improving readability, debugging, and eliminating zero-value issues. This change enhances the overall **security and robustness** of credential handling by providing explicit, type-aware loading functions. Users should migrate to the new `NewCredentialsFromJSON` and `NewCredentialsFromFile` functions for both `credentials` and `idtoken` packages.

This **maintenance chore** commit **removes the Cloud Build trigger** for the `gcr.io/cloud-devrel-public-resources/librarian-go` Docker image, streamlining the build infrastructure for the **`internal/librariangen` tool**. Concurrently, it performs a significant **documentation update** to `internal/librariangen/README.md`. This update removes outdated Docker container build information and adds new, comprehensive instructions for running Librarian via its CLI. The changes improve the clarity and accuracy of the `librariangen` usage guide, particularly for creating release PRs and adding new APIs, enhancing the developer experience.

This commit performs a significant **refactoring** of the internal routing header construction logic across numerous gRPC client methods within several Google Cloud API client libraries. Driven by an update to the `librarian-go` image, this change impacts **Cloud Build**, **Firestore Admin**, **Fleet Engine (Trip, Vehicle, Delivery)**, **Cloud Run (Jobs, Revisions, Services, Worker Pools)**, **Security Command Center**, and **Storage (Control, Internal)**. The **refactoring** standardizes how routing information is generated for API requests, enhancing the consistency and correctness of client-side gRPC interactions. This broad internal update affects a wide array of methods, including those for creating, getting, listing, and managing resources across these services.

This commit performs a **maintenance update** by bumping the version of `gapic-generator-go` used within the **internal/librariangen** module. Specifically, the `GAPIC_GENERATOR_VERSION` environment variable in the `Dockerfile` is updated from `0.54.0` to `0.55.0`. This ensures that all subsequent client library generation processes leverage the latest features, improvements, and bug fixes provided by `gapic-generator-go` version `0.55.0`. The change primarily affects the **tooling and generation pipeline** for GAPIC clients, ensuring consistency with the latest generator capabilities.

This commit performs a **maintenance chore** by **refactoring** the testing approach within the **`internal/librariangen` module**. It **removes temporary, ad-hoc development test scripts** that were previously used for manual testing. These scripts are now superseded by the more standardized `librarian update-image -test` command, streamlining the testing workflow. Consequently, the `internal/librariangen/GEMINI.md` documentation is updated to reflect these changes, removing outdated instructions for binary integration tests and references to the old shell scripts. This improves consistency and reduces manual overhead for developers working on `librariangen`.

This commit introduces a **new capability** to the `internal/librariangen` tool, enabling the **automatic generation of `.repo-metadata.json` files** for API client libraries. New logic in `internal/librariangen/generate/manifest.go` handles metadata extraction and formatting, while the `.librarian/state.yaml` configuration is updated to include these generated files. This **maintenance enhancement** standardizes client documentation URLs and library types across various API clients, improving consistency and reducing manual effort in managing library metadata.

This commit **fixes** a **bug** in the **`internal/librariangen`** tool's `configure` sub-package, which was incorrectly generating package names for `version.go` files in complex client directory structures. It ensures that the generated `version.go` files have the correct package declarations and that `RemoveRegex` entries are properly relative to the repository root. This **maintenance** update improves the robustness of the code generation process, preventing potential build or import issues for client libraries. A new test case has been added to validate the correct package name and `RemoveRegex` generation for these intricate scenarios.

This commit **refines the `apidiff` workflow** by introducing conditional failure logic for API breaking changes. Previously, any API breaking change would cause the workflow to fail; now, it will **only fail for GA (Generally Available) API breaking changes**. For non-GA APIs, the workflow will instead **post a comment to the pull request**, providing feedback without blocking the merge. This **maintenance update** to the **`.github/workflows/apidiff.yml`** file improves the CI/CD process by making API compatibility checks more nuanced and developer-friendly, ensuring strictness for stable APIs while offering flexibility for those still in development.

This commit **refines logging levels** within the **`internal/librariangen`** tool to enhance its observability and debuggability. It demotes verbose messages to `Debug` in `configure`, `main`, and `release` packages, while promoting critical operations like `go mod init` and `go mod tidy` in the `postprocessor` and internal version file generation in `module` to `Info` level. A new `Info` log is also added for `go mod edit -replace` command execution. Furthermore, **new unit tests** are introduced for the `postprocessor` to ensure robust handling of `go mod init` and `go mod tidy` operations. This **maintenance** effort improves the clarity of the tool's execution flow and strengthens its test coverage.

This commit **introduces a new client library** for the **GKE Inference Quickstart API** within the `gkerecommender` module. This **new capability** provides developers with a dedicated `GkeInferenceQuickstartClient` to programmatically interact with the API, enabling operations such as fetching models, model servers, and profiles, and generating optimized manifests. The work includes the core client implementation, auxiliary types, comprehensive documentation, example tests, and usage snippets, making the new client fully functional and discoverable. This significantly expands the project's integration with Google Cloud services by adding support for GKE inference recommendations.

This commit performs **maintenance** by updating the `librarian-go` container image SHA in `.librarian/state.yaml` to its latest version. Additionally, it addresses stale client library versions within the generated snippet metadata for various **Spanner client library modules**, such as `adapter`, `admin/database`, and `admin/instance`. This **chore** ensures the **Librarian system** utilizes the most current tooling and that **Spanner** code snippets accurately reflect up-to-date client library versions. These snippet metadata updates resolve inconsistencies left behind during initial Librarian onboarding and were validated by `librarian update-image` testing.

This commit **enhances the testing infrastructure** for the **`internal/librariangen`** module by adding new tests for its `configure` functionality. It introduces a comprehensive **unit test suite** in `configure_test.go` for the `Configure` function, alongside a new `run-binary-configure-test.sh` script for **integration testing** the `librariangen configure` command. These **testing enhancements** improve the **reliability and correctness** of the configuration process. Specifically, the tests validate the setup for `capacityplanner` and `secretmanager` components by simulating the Librarian tool's environment and updating test data with relevant library IDs and API paths.

This commit delivers a **bug fix** and **enhancement** to the `internal/gapicgen` module, resolving a critical issue where the **genbot** would crash when processing Git history containing deleted proto files. The `gatherChanges` function in `internal/gapicgen/generator/generator.go` is updated to retrieve file content directly from the historical Git commit, rather than the current filesystem. This is facilitated by a new `GetFileContentAtCommit` function added to `internal/gapicgen/git/git.go`, which provides the capability to fetch file content at a specific commit hash. The change significantly improves the **genbot**'s robustness, preventing crashes and ensuring stable operation when encountering file deletions or renames in the repository history.

This commit provides a **bug fix** for the **`internal/gapicgen`** module, specifically improving the robustness of its code generation process. It modifies the `gatherChanges` function in `generator.go` to **skip empty file paths**, preventing potential issues that could arise from malformed inputs. Additionally, the `Generate` function's error handling is enhanced to properly wrap underlying errors, contributing to more reliable diagnostics. This ensures the **`gapicgen` tool** can more gracefully handle edge cases related to file path processing, improving overall stability.

This commit introduces a **new capability** to the **`internal/gapicgen` module** that **fixes an issue** with `genbot`'s pull request description generation for `go-genproto` regenerations. Previously, overly long descriptions could be rejected by GitHub; now, the `gatherChanges` function in `generator.go` intelligently filters commits to include only those that affected watched proto files. The `git` package's `truncateAndFormatChanges` function is updated to present these relevant commits, along with the specific proto packages they impacted, ensuring more concise and pertinent PR descriptions. This significantly improves the automation workflow by preventing GitHub rejections and providing clearer context for changes.