[accless] Support Multi Attestation-Service Deployments

[csegarragonz]

Closes #49

[gemini-code-assist]

Summary of Changes

Hello @csegarragonz, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces comprehensive support for deploying and interacting with multiple attestation services, significantly enhancing the system's flexibility and scalability. The changes span across the accli tool for provisioning and running applications, the core attestation libraries, and example applications, ensuring that the entire ecosystem can adapt to distributed attestation authority deployments. This enables more robust and resilient confidential computing environments.

Highlights

• Multi-Attestation Service Support: The system now supports deploying and interacting with multiple attestation services, moving from single environment variables for URLs and certificates to handling lists and directories.
• Updated accli Tooling: The accli command-line interface has been updated to manage multiple attestation service instances, including new arguments for specifying multiple URLs and certificate directories, and modifications to Azure provisioning for multi-VM deployments.
• Application Code Adaptations: Applications like escrow-xput, hello-snp, and breakdown-snp have been refactored to accept multiple attestation service URLs and certificate paths, and to construct CP-ABE policies that can leverage these distributed authorities.
• Build System Enhancements: The build system (applications/build.py, CMakeLists.txt, jwt/build.rs) has been adjusted to process certificate directories instead of single files, enabling the embedding of multiple certificates into binaries.
• New Test Application: A new test application, multi-as, has been introduced to specifically validate the functionality of interacting with multiple attestation services.

Ignored Files

• Ignored by pattern: .github/workflows/** (1)
  • .github/workflows/snp.yml

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Code Review

This pull request introduces significant changes to support multiple attestation services and refactors how certificate paths are handled, moving from single PEM files to directories of certificates. Key changes include updating Cargo.lock for dependency bumps, adding a size check in abe4.cpp for robustness, and modifying attestation-related C++ functions (attestation.cpp, attestation.h, mock_sgx.cpp, mock_snp.cpp, snp.cpp) to accept asUrl and certPath as parameters instead of relying on environment variables. The Rust build script (jwt/build.rs) and CMake configuration (jwt/cpp-bindings/CMakeLists.txt) were updated to embed multiple .pem certificates from a specified directory (ACCLESS_AS_CERT_DIR). The accli command-line tool was refactored to remove a global debug flag, add an id argument for attestation services, and replace single cert_path arguments with cert_dir arguments. The accli now uses an ApplicationBackend enum (Cvm, Docker) for running applications, simplifying the execution logic. Azure provisioning scripts were enhanced to dynamically create and provision multiple attestation service VMs, and Ansible playbooks were updated to handle dynamic inventory and per-VM variables. A new multi-as test application was added to validate multi-attestation service functionality. The escrow-xput function was updated to support multiple attestation service URLs and certificate paths, and its CP-ABE policy logic was adjusted for load-balancing across multiple services. Plotting scripts were also updated to include a new AcclessSingleAuth baseline and temporarily skip plotting AcclessMaa. Review comments highlighted the need for more descriptive error messages when unwrap() is used in build.rs and suggested extracting duplicated VM name generation logic in accli/src/main.rs into a helper function for better maintainability.