Use container UUID instead of IP address for tracking agent

[sjberman]

Problem: In some cases, a Pod's IP address may not actually be the IP of the Pod. It could be the IP of the node it's running on. This makes verification and tracking difficult to impossible.

Solution: Use the UUID of the container instead of the IP address, and loosen the validation to not care about the address that connects to the control plane.

Also needed to fix the agent's ability to identify us as a container, because otherwise the UUId was of the node, not the container. This involved reverting a previous fix that was added after removing the default service account directory, which agent looked for.

Testing: Verified that everything still works when not using the IP address as the key.

Partially addresses #4426

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

Release notes

If this PR introduces a change that affects users and needs to be mentioned in the release notes,
please add a brief note that summarizes the change.

Fix issue where agent's Pod IP cannot be used to track the connecting data plane Pod

[Copilot]

Pull request overview

This PR changes the agent tracking mechanism from using Pod IP addresses to using Pod UUIDs to address scenarios where a Pod's IP address may not accurately represent the Pod (e.g., when it's actually the node's IP). The change relaxes validation requirements and fixes the agent's container identification by creating an empty /run/.containerenv file in Docker images.

• Replaced IP-based tracking with UUID-based tracking across the gRPC interceptor and command/file services
• Removed IP address validation logic in favor of UUID validation
• Added /run/.containerenv file creation in Dockerfiles to ensure proper container identification

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
internal/controller/nginx/agent/grpc/interceptor/interceptor.go	Replaced IP address extraction from peer data with UUID from metadata; removed IP-based pod filtering
internal/controller/nginx/agent/grpc/interceptor/interceptor_test.go	Updated tests to remove peer/IP validation and use UUID-based tracking
internal/controller/nginx/agent/grpc/context/context.go	Changed GrpcInfo struct to use UUID field instead of IPAddress
internal/controller/nginx/agent/grpc/context/context_test.go	Updated test to use Token field instead of IPAddress
internal/controller/nginx/agent/command.go	Replaced all IPAddress references with UUID for connection tracking
internal/controller/nginx/agent/command_test.go	Updated tests to use UUID-based tracking and removed hostname fallback test
internal/controller/nginx/agent/file.go	Changed file service methods to use UUID instead of IPAddress
internal/controller/nginx/agent/file_test.go	Updated all test contexts to use UUID instead of IPAddress
build/Dockerfile.nginx	Added creation of /run/.containerenv file for container identification
build/Dockerfile.nginxplus	Added creation of /run/.containerenv file for container identification
build/ubi/Dockerfile.nginx	Added creation of /run/.containerenv file for container identification
build/ubi/Dockerfile.nginxplus	Added creation of /run/.containerenv file for container identification

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.23%. Comparing base (c2f7394) to head (ebf34be).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4470      +/-   ##
==========================================
- Coverage   86.24%   86.23%   -0.01%     
==========================================
  Files         132      132              
  Lines       14566    14557       -9     
  Branches       35       35              
==========================================
- Hits        12562    12553       -9     
  Misses       1791     1791              
  Partials      213      213              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.