Fix runtime error with grpcio

[Bihan]

Fixes issue #3957
Supporting grpcio<1.81 would require pinning smg-grpc-proto<=0.4.8, since 0.4.9+ stubs enforce grpcio>=1.81 at import time. Pinning smg-grpc-proto<=0.4.8 keeps us on older pre-built stubs and blocks newer fixes, which is risky long-term. Therefore this PR prefers pinning grpcio>=1.81.0 instead.

[jvstme]

The latest smg-grpc-proto==0.4.10 now implicitly depends on grpcio>=1.81.1, so the steps to reproduce from the issue are still relevant, just with grpcio<1.81.1.

$ rm -rf .venv
$ git checkout Bihan/fix_issue_3957_runtime_error_with_grpcio
$ uv venv
$ uv pip install "grpcio<1.81.1"
$ uv pip install .[all] --refresh
$ ./.venv/bin/dstack server
  File "/dstack/.venv/lib/python3.13/site-packages/smg_grpc_proto/generated/mlx_engine_pb2_grpc.py", line 21, in <module>
    raise RuntimeError(
    ...<5 lines>...
    )
RuntimeError: The grpc package installed is at version 1.81.0, but the generated code in mlx_engine_pb2_grpc.py depends on grpcio>=1.81.1. Please upgrade your grpc module to grpcio>=1.81.1 or downgrade your generated code using grpcio-tools<=1.81.0.

Looking at some of the previous smg-grpc-proto releases, it seems that they bump the implicit grpcio dependency quite often.

$ pip install smg-grpc-proto==0.4.10
$ sed -n 8p /tmp/venv/lib64/python3.14/site-packages/smg_grpc_proto/generated/common_pb2_grpc.py
GRPC_GENERATED_VERSION = '1.81.1'
$ pip install smg-grpc-proto==0.4.9
$ sed -n 8p /tmp/venv/lib64/python3.14/site-packages/smg_grpc_proto/generated/common_pb2_grpc.py
GRPC_GENERATED_VERSION = '1.81.0'
$ pip install smg-grpc-proto==0.4.8
$ sed -n 8p /tmp/venv/lib64/python3.14/site-packages/smg_grpc_proto/generated/common_pb2_grpc.py
GRPC_GENERATED_VERSION = '1.80.0'
$ pip install smg-grpc-proto==0.4.5
$ sed -n 8p /tmp/venv/lib64/python3.14/site-packages/smg_grpc_proto/generated/common_pb2_grpc.py
GRPC_GENERATED_VERSION = '1.78.0'

I assume this means that we will keep seeing the RuntimeError issue in the future, unless we pin smg-grpc-proto, or unless smg-grpc-proto can specify what grpcio version it needs in its package dependencies.

[r4victor]

Seems restrictive to bump grpcio to the latest version constantly. How about making smg-grpc-proto an optional dep to limit the blast radius?

[jvstme]

making smg-grpc-proto an optional dep

I'm not sure, it will add an extra setup step for our users to get the SMG integration running, and users that need the integration will still have to deal with a potential version mismatch. If we add it to the all extra, then users that install dstack[all] will have to deal with it too.

I think I would prefer to restrict the smg-grpc-proto version for now.

And optionally ask its maintainers to address the issue on their side. I don't know if there are any established best practices for shipping gRPC SDKs as Python packages, but I assume the package could at least:

• Specify the required gRPC version in its dependencies.
• Be built against an older gRPC version, so as not to require all users to have the latest version.

best practices for shipping gRPC SDKs

By the way, google packages don't seem to have that runtime version check.

[Bihan]

So for now I will update the PR with

smg-grpc-proto==0.4.9
grpcio>=1.81.0