🚀 CI Improvements in dotnet/aspnetcore

[wtgodbe]

We've recently landed several PRs aimed at making it faster and more reliable to get a PR merged into dotnet/aspnetcore. The focus has been on:

🛠️ Build time
🔁 Build reliability
✅ Test reliability

📌 Key PRs

• Only run template tests when templates change #62481 – Run Template Tests only on relevant PRs
• Add pipeline that's always green, for doc-only PRs #62509 – Add “Always Green” PR check for doc-only changes
• Split helix into subsets #62644 – Split Helix tests into two subsets
• Limit paths that trigger components-e2e pipeline #62811 – Run Components-E2E tests only on relevant PRs
• Swap out Win11 for Win-VS2022 in CI #61743 – Swapped Win11 Helix queue for Win-VS2022 queue in CI

📊 Results (based on rolling public builds of the main branch)

• ✅ Build pass rate improved from 52.3% (past 6 months) to 76.2% (past week)
• 🧪 Test failure rate dropped from 0.002% to 0.0004% after the Helix queue switch — a 5x increase in reliability
• 🖥️ Weekly test failures on the new VS2022 queue: 2 (1 quarantined) vs. 29 on the old Win11 queue
• ⏱️ Build duration reduced from 2h 25m to 1h 11m — more than 50% faster!

🔍 What’s Next?

We're continuing to drive down flakiness in builds and tests. Next up:

• Investigating common build failures like Known Build Error: error : Cannot create a file when that file already exists. #61178
• Tackling remaining flaky tests
• Continuing to update this issue with future improvements

💡 Got ideas to improve the CI experience further? Drop them in the comments — we’d love to hear from you!

[martincostello]

Maybe #56408 would speed things up?

[wtgodbe]

Maybe #56408 would speed things up?

I'm actually touching the ANCM build right now in #62885 - I'll give it a try!