feat(force-dp-check): adding test to validate the force-dp using proxy server

[raj-prince]

Description

1. Update emulator.sh to start gRPC emulator server.
2. Implemented gRPC proxy server to accept gRPC traffic from GCSFuse and pass it on emulator service (although right now not needed but useful in future for gRPC related emulator based test). Added header validation check in proxy server.
3. Added test to confirm gRPC traffic contains the required header - (a) force_direct_connectivity & (b) direct_connectivity_diagnostic

Link to the issue in case of a bug fix.

b/493748028

Testing details

1. Manual - Yes.
2. Unit tests - NA
3. Integration tests - Yes (tested manually).

Any backward incompatible change? If so, please explain.

[gemini-code-assist]

Summary of Changes

Hello, 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 significantly enhances the integration testing capabilities by introducing a gRPC proxy server. This proxy is designed to intercept and validate gRPC request headers, specifically ensuring that GCSFuse clients correctly transmit DirectPath connectivity metadata. This addition is crucial for verifying the proper functioning of gRPC-based interactions with the storage emulator, providing a robust mechanism to confirm expected header behavior during various file operations.

Highlights

• gRPC Proxy Server Implementation: A new gRPC proxy server has been implemented, capable of intercepting and forwarding gRPC traffic to a target host.
• gRPC Header Validation: Header validation logic was added to the gRPC proxy, allowing it to check for specific headers and expected patterns in incoming gRPC requests. This is configurable via a YAML file.
• Integration Tests for DirectPath Connectivity: New integration tests were introduced to validate that GCSFuse clients send the required DirectPath connectivity metadata (e.g., 'force_direct_connectivity=ENFORCED') in gRPC request headers when interacting with the storage emulator through the proxy.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (f156c3e) to head (4563a4d).
⚠️ Report is 19 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #4500       +/-   ##
==========================================
- Coverage   83.73%       0   -83.74%     
==========================================
  Files         163       0      -163     
  Lines       20021       0    -20021     
==========================================
- Hits        16764       0    -16764     
+ Misses       2640       0     -2640     
+ Partials      617       0      -617     

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[gemini-code-assist]

Code Review

This pull request introduces a gRPC proxy server and a new integration test to validate that gRPC calls contain specific headers when force-dp is enabled. The implementation of the gRPC proxy using a raw codec and an unknown service handler is a solid approach for transparently forwarding requests. The new test suite effectively verifies the header presence for various file system operations.

I've found one issue in the gRPC server's shutdown handling that would cause it to crash during a normal shutdown. A fix is suggested. Overall, this is a great addition for ensuring DirectPath connectivity behavior.

[github-actions]

Hi @Tulsishah, @meet2mky, @vadlakondaswetha, your feedback is needed to move this pull request forward. This automated reminder was triggered because there has been no activity for over 24 hours. Please provide your input when you have a moment. Thank you!

[meet2mky]

Overall looks good. Few minor comments.

[meet2mky]

LGTM