Add Bazel 8.5.0 build support for simple_switch_grpc + CI workflow

[kunal9812]

Summary

This PR adds Bazel 8.5.0 build support for simple_switch_grpc as part of
the GSoC 2026 qualification task for Project 1.1: BMv2 Packet Trace Support.

What This PR Does

• Adds MODULE.bazel with bzlmod dependencies (protobuf 29.1, grpc 1.71,
  boost, jsoncpp, fmt, googletest)
• Adds WORKSPACE.bzlmod to enable Bazel bzlmod mode
• Adds BUILD file at root for bmv2_core library
• Adds BUILD file for targets/simple_switch_grpc
• Vendors PI library headers/sources into third_party/PI
• Adds .github/workflows/ci-bazel.yml — builds and tests via Bazel

Verification

• bazelisk build //targets/simple_switch_grpc:simple_switch_grpc passes
• bazelisk test //targets/simple_switch_grpc:simple_switch_grpc_test — 23/26 pass (3 gNMI/multicast tests require a running network service)

Notes

• Built and tested on macOS M1 with Bazel 8.5.0 (via bazelisk + .bazelversion)
• The 3 failing tests (gNMI.PortOperStatusUpdates, gNMI.PortCounters, Clone.SingletonAndMulticast) require a live gNMI/multicast environment and fail the same way on the original codebase

Related

GSoC 2026 Project 1.1 qualification task.
Reference repos: p4lang/p4runtime (Bazel structure), p4lang/p4c (CI workflow).

[fruffy]

You should not vendor the dependencies in third party. If we need PI, it makes sense to create a Bazel build there first.

@matthewtlam

[qobilidop]

@kunal9812 Please make sure all the existing CIs pass. And besides that, please add a new CI to test the Bazel build and demonstrate it passes as well.

[kunal9812]

Thank you for the feedback! I understand — vendoring PI sources was a pragmatic workaround to get the build working.
I'll work on:
-Adding Bazel MODULE.bazel + BUILD files to p4lang/PI
-Updating the BMv2 BUILD to reference PI as an external dep
-Getting the CI workflow to pass
Will update the PR shortly.

[matthewtlam]

+1 to what @fruffy mentioned. We should not be vendoring our dependencies in 3rd party. These should be gracefully handled using Bazel

Please make sure all the builds are working

[matthewtlam]

Thanks for your PR @kunal9812

None of the PRs will be carefully reviewed until Apr 1 (once the contributor deadline is over). Starting today (March 16th), the GSoC contributor application will open. Please make sure you submit your application before the deadline.

During the first week of April, after applications and PRs are reviewed, candidates who will be considered will be sent an interview. The contributor who gets admitted into GSoC will have their PR pushed to head

cc: @qobilidop

[kunal9812]

Hi @fruffy and @qobilidop — thank you for the feedback!
I’ve addressed both issues:

• Removing Vendoring PI dependencies from 3rd party, instead of vendoring PI sources into third_party/PI/, I’ve added proper bzlmod support (MODULE.bazel) to the PI repository itself: Add Bazel bzlmod support (MODULE.bazel) PI#629

• Existing CI failures - The CMake CI failures are pre-existing on the main branch and unrelated to this PR. I verified that by running git stash locally and confirming the same failures occur without any of these changes.