Looking to bump protobuf dependency > 7.0.0

[ericzundel]

I'm trying to upgrade bazel build rules:

In my MODULE.bazel I upgraded as follows:

 ####################################################
 # Protobuf rules
 # This is the Way to load py_proto_library and proto_library for bazel 7.x and beyond
 #
-bazel_dep(name = "protobuf", version = "33.5", dev_dependency = True)
+bazel_dep(name = "protobuf", version = "34.1", dev_dependency = True)

-bazel_dep(name = "rules_python", version = "1.8.3")
+bazel_dep(name = "rules_python", version = "1.9.0")

The protobuf rules bump has led me to an unresolvable constraint in the spanner
driver. First I tried with 3.59.0, then I increased the google-cloud-spanner version up to the latest 3.63.0.

$ update-requirements-lock.sh 
  × No solution found when resolving dependencies:
  ╰─▶ Because google-cloud-spanner==3.63.0 depends on one of:
          protobuf>=3.20.2,<4.21.0
          protobuf>4.21.0,<4.21.1
          protobuf>4.21.1,<4.21.2
          protobuf>4.21.2,<4.21.3
          protobuf>4.21.3,<4.21.4
          protobuf>4.21.4,<4.21.5
          protobuf>4.21.5,<7.0.0
      and you require protobuf>=7.34.1, we can conclude that your requirements and google-cloud-spanner==3.63.0 are incompatible.
      And because you require google-cloud-spanner==3.63.0, we can conclude that your requirements are unsatisfiable.

I'm not sure if there is good reason to have the <7.0.0 constraint on the protobuf package. The new protobuf rules seem to use: 7.34.1 by default. Here are the release notes for 7.x: https://protobuf.dev/news/2025-09-19/ from September 2025

[ericzundel]

Note, this isn't blocking for me, I just moved to protobuf 33.6 for now.

[olavloite]

Assigning to @parthea as the last to update this specifically to <7.0.0 in googleapis/python-spanner#1320.

Is there a specific reason for requiring <7.0.0?

[parthea]

We're currently blocked on grpc/grpc#41933. There is a dependency on grpcio-status via the grpc extra of google-api-core (google-api-core[grpc]).

https://github.com/googleapis/python-spanner/blob/c37532c65ee2b2ecc52d8a4a2f5bf002cb8e039c/setup.py#L43

google-cloud-python/packages/google-api-core/pyproject.toml

Lines 63 to 70 in 4b400fa

	grpc = [
	"grpcio >= 1.33.2, < 2.0.0",
	"grpcio >= 1.49.1, < 2.0.0; python_version >= '3.11'",
	"grpcio >= 1.75.1, < 2.0.0; python_version >= '3.14'",
	"grpcio-status >= 1.33.2, < 2.0.0",
	"grpcio-status >= 1.49.1, < 2.0.0; python_version >= '3.11'",
	"grpcio-status >= 1.75.1, < 2.0.0; python_version >= '3.14'",
	]

We should be able to allow Protobuf 7.x in client libraries because we have prerelease tests via the Kokoro Prerelease Dependencies presubmit that runs against Protobuf 7.x, but we will still see conflicts due to grpcio-status.

In the build log for Kokoro Prerelease Dependencies , see this line where we have already tested Protobuf 7.x

nox > python -c 'import google.protobuf; print(google.protobuf.__version__)'
7.34.1

We can't run tests using Protobuf 7.x outside of Kokoro Prerelease Dependencies because of grpc/grpc#41933.

Googlers see b/495851781

[parthea]

Transferring to google-cloud-python as the code for google-cloud-spanner will be migrated there this week (likely tomorrow)