feat(grpc): Add protobuf codegen

.github/workflows/CI.yml

@@ -25,14 +25,74 @@ jobs:
         components: rustfmt
     - run: cargo fmt --all --check
 
+  build-protoc-plugin:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macOS-latest, windows-latest]
+    outputs:
+      cache-hit: ${{ steps.cache-plugin.outputs.cache-hit }}
+    steps:
+      - uses: actions/checkout@v4
+      - name: Cache protoc plugin
+        id: cache-plugin
+        uses: actions/cache@v4
+        with:
+          path: ${{ runner.temp }}/protoc-plugin
+          # The key changes only when plugin source files change
+          key: ${{ runner.os }}-protoc-plugin-${{ hashFiles('protoc-gen-rust-grpc/src/**', 'protoc-gen-rust-grpc/.bazelrc', 'protoc-gen-rust-grpc/MODULE.bazel') }}
+      - name: Install Bazel
+        if: steps.cache-plugin.outputs.cache-hit != 'true'
+        uses: bazel-contrib/setup-bazel@0.15.0
+        with:
+          # Avoid downloading Bazel every time.
+          bazelisk-cache: true
+          # Store build cache per workflow.
+          disk-cache: ${{ github.workflow }}
+          # Share repository cache between workflows.
+          repository-cache: true
+          module-root: ./protoc-gen-rust-grpc
+      # Building the protoc plugin from scratch takes 6–14 minutes, depending on
+      # the OS. This delays the execution of workflows that use the plugin in
+      # build.rs files. We try to avoid rebuilding the plugin if it hasn't
+      # changed.
+      - name: Build protoc plugin
+        if: steps.cache-plugin.outputs.cache-hit != 'true'
+        working-directory: ./protoc-gen-rust-grpc
+        shell: bash
+        run: |
+          set -e
+          # On windows, the "//src" gets converted to "/". Disable this path
+          # conversion.
+          export MSYS_NO_PATHCONV=1
+          export MSYS2_ARG_CONV_EXCL="*"
+
+          bazel build //src:protoc-gen-rust-grpc --enable_platform_specific_config
+
+          # The target path needs to match the cache config.
+          TARGET_PATH="${{ runner.temp }}/protoc-plugin"
+          mkdir -p "${TARGET_PATH}"
+          cp bazel-bin/src/protoc-gen-rust-grpc "${TARGET_PATH}"
+
   clippy:
     runs-on: ubuntu-latest
+    needs: build-protoc-plugin
     steps:
     - uses: actions/checkout@v4
     - uses: hecrj/setup-rust-action@v2
       with:
         components: clippy
     - uses: taiki-e/install-action@protoc
+    - name: Restore protoc plugin from cache
+      id: cache-plugin
+      uses: actions/cache@v4
+      with:
+        path: ${{ runner.temp }}/protoc-plugin
+        key: ${{ runner.os }}-protoc-plugin-${{ hashFiles('protoc-gen-rust-grpc/src/**', 'protoc-gen-rust-grpc/.bazelrc', 'protoc-gen-rust-grpc/MODULE.bazel') }}
+    - name: Add protoc plugin to PATH
+      shell: bash
+      run: |
+        echo "${{ runner.temp }}/protoc-plugin" >> $GITHUB_PATH
     - uses: Swatinem/rust-cache@v2
     - run: cargo clippy --workspace --all-features --all-targets
 
@@ -47,6 +107,7 @@ jobs:
 
   udeps:
     runs-on: ubuntu-latest
+    needs: build-protoc-plugin
     steps:
     - uses: actions/checkout@v4
     - uses: dtolnay/rust-toolchain@master
@@ -55,6 +116,16 @@ jobs:
     - uses: taiki-e/install-action@cargo-hack
     - uses: taiki-e/install-action@cargo-udeps
     - uses: taiki-e/install-action@protoc
+    - name: Restore protoc plugin from cache
+      id: cache-plugin
+      uses: actions/cache@v4
+      with:
+        path: ${{ runner.temp }}/protoc-plugin
+        key: ${{ runner.os }}-protoc-plugin-${{ hashFiles('protoc-gen-rust-grpc/src/**', 'protoc-gen-rust-grpc/.bazelrc', 'protoc-gen-rust-grpc/MODULE.bazel') }}
+    - name: Add protoc plugin to PATH
+      shell: bash
+      run: |
+        echo "${{ runner.temp }}/protoc-plugin" >> $GITHUB_PATH
     - uses: Swatinem/rust-cache@v2
     - run: cargo hack udeps --workspace --exclude-features=_tls-any,tls,tls-aws-lc,tls-ring --each-feature
     - run: cargo udeps --package tonic --features tls-ring,transport
@@ -66,6 +137,7 @@ jobs:
 
   check:
     runs-on: ${{ matrix.os }}
+    needs: build-protoc-plugin
     strategy:
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
@@ -76,6 +148,16 @@ jobs:
     - uses: hecrj/setup-rust-action@v2
     - uses: taiki-e/install-action@cargo-hack
     - uses: taiki-e/install-action@protoc
+    - name: Restore protoc plugin from cache
+      id: cache-plugin
+      uses: actions/cache@v4
+      with:
+        path: ${{ runner.temp }}/protoc-plugin
+        key: ${{ runner.os }}-protoc-plugin-${{ hashFiles('protoc-gen-rust-grpc/src/**', 'protoc-gen-rust-grpc/.bazelrc', 'protoc-gen-rust-grpc/MODULE.bazel') }}
+    - name: Add protoc plugin to PATH
+      shell: bash
+      run: |
+        echo "${{ runner.temp }}/protoc-plugin" >> $GITHUB_PATH
     - uses: Swatinem/rust-cache@v2
     - name: Check features
       run: cargo hack check --workspace --no-private --each-feature --no-dev-deps
@@ -108,13 +190,24 @@ jobs:
 
   test:
     runs-on: ${{ matrix.os }}
+    needs: build-protoc-plugin
     strategy:
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
     steps:
     - uses: actions/checkout@v4
     - uses: hecrj/setup-rust-action@v2
     - uses: taiki-e/install-action@protoc
+    - name: Restore protoc plugin from cache
+      id: cache-plugin
+      uses: actions/cache@v4
+      with:
+        path: ${{ runner.temp }}/protoc-plugin
+        key: ${{ runner.os }}-protoc-plugin-${{ hashFiles('protoc-gen-rust-grpc/src/**', 'protoc-gen-rust-grpc/.bazelrc', 'protoc-gen-rust-grpc/MODULE.bazel') }}
+    - name: Add protoc plugin to PATH
+      shell: bash
+      run: |
+        echo "${{ runner.temp }}/protoc-plugin" >> $GITHUB_PATH
     - uses: taiki-e/install-action@cargo-hack
     - uses: taiki-e/install-action@cargo-nextest
     - uses: Swatinem/rust-cache@v2
@@ -134,13 +227,24 @@ jobs:
   interop:
     name: Interop Tests
     runs-on: ${{ matrix.os }}
+    needs: build-protoc-plugin
     strategy:
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
     steps:
     - uses: actions/checkout@v4
     - uses: hecrj/setup-rust-action@v2
     - uses: taiki-e/install-action@protoc
+    - name: Restore protoc plugin from cache
+      id: cache-plugin
+      uses: actions/cache@v4
+      with:
+        path: ${{ runner.temp }}/protoc-plugin
+        key: ${{ runner.os }}-protoc-plugin-${{ hashFiles('protoc-gen-rust-grpc/src/**', 'protoc-gen-rust-grpc/.bazelrc', 'protoc-gen-rust-grpc/MODULE.bazel') }}
+    - name: Add protoc plugin to PATH
+      shell: bash
+      run: |
+        echo "${{ runner.temp }}/protoc-plugin" >> $GITHUB_PATH
     - uses: Swatinem/rust-cache@v2
     - name: Run interop tests
       run: ./interop/test.sh

Cargo.toml

@@ -3,6 +3,8 @@ members = [
   "tonic",
   "tonic-build",
   "tonic-health",
+  "tonic-protobuf",
+  "tonic-protobuf-build",
   "tonic-types",
   "tonic-reflection",
   "tonic-prost",

grpc/src/lib.rs

@@ -34,6 +34,7 @@
 pub mod client;
 pub mod credentials;
 pub mod inmemory;
+mod macros;
 pub mod rt;
 pub mod server;
 pub mod service;

grpc/src/macros.rs

@@ -0,0 +1,104 @@
+/*
+ *
+ * Copyright 2025 gRPC authors.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+/// Includes generated proto message, client, and server code.
+///
+/// You must specify the path to the `.proto` file
+/// **relative to the proto root directory**,  without the `.proto` extension.  
+///
+/// For example, if your proto directory is `path/to/protos` and it contains the
+/// file  `helloworld.proto`, you would write:
+///
+/// ```rust,ignore
+/// mod pb {
+///     grpc::include_proto!("path/to/protos", "helloworld");
+/// }
+/// ```
+///
+/// # Note
+/// **This macro only works if the gRPC build output directory and message path
+/// are unmodified.**
+/// By default:
+/// - The output directory is set to the [`OUT_DIR`] environment variable.
+/// - The message path is set to `self`.
+///
+/// If your `.proto` files are not in a subdirectory, you can omit the first
+/// parameter.
+///
+/// ```rust,ignore
+/// mod pb {
+///     grpc::include_proto!("helloworld");
+/// }
+/// ```
+///
+/// If you have modified the output directory or message path, you should
+/// include the generated code manually instead of using this macro.
+///
+/// The following example assumes the message code is imported using `self`:
+///
+/// ```rust,ignore
+/// mod protos {
+///     // Include message code.
+///     include!("relative/protobuf/directory/generated.rs");
+///
+///     // Include service code.
+///     include!("relative/protobuf/directory/helloworld_grpc.pb.rs");
+/// }
+/// ```
+///
+/// If the message code and service code are in different modules, and the
+/// message path specified during code generation is `super::protos`, use:
+///
+/// ```rust,ignore
+/// mod protos {
+///     // Include message code.
+///     include!("relative/protobuf/directory/generated.rs");
+/// }
+///
+/// mod grpc {
+///     // Include service code.
+///     include!("relative/protobuf/directory/helloworld_grpc.pb.rs");
+/// }
+/// ```
+///
+/// [`OUT_DIR`]: https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-build-scripts
+#[macro_export]
+macro_rules! include_proto {
+    // Assume the generated output dir is OUT_DIR.
+    ($proto_file:literal) => {
+        $crate::include_proto!("", $proto_file);
+    };
+
+    ($parent_dir:literal, $proto_file:literal) => {
+        include!(concat!(env!("OUT_DIR"), "/", $parent_dir, "/generated.rs"));
+        include!(concat!(
+            env!("OUT_DIR"),
+            "/",
+            $parent_dir,
+            "/",
+            $proto_file,
+            "_grpc.pb.rs"
+        ));
+    };
+}

interop/Cargo.toml

@@ -26,6 +26,15 @@ tonic = {path = "../tonic", features = ["tls-ring"]}
 tonic-prost = {path = "../tonic-prost"}
 tower = "0.5"
 tracing-subscriber = {version = "0.3"}
+grpc = {path = "../grpc"}
+# TODO: Remove the direct protobuf dependency after updating to version 4.32,
+# which includes https://github.com/protocolbuffers/protobuf/pull/22764.
+# We also need the protobuf-codegen crate to support configuring the path
+# to the protobuf crate used in the generated message code, instead of
+# defaulting to `::protobuf`.
+protobuf = { version = "4.31.1-release" }
+tonic-protobuf = {path = "../tonic-protobuf"}
 
 [build-dependencies]
 tonic-prost-build = {path = "../tonic-prost-build"}
+tonic-protobuf-build = {path = "../tonic-protobuf-build"}

interop/build.rs

@@ -2,6 +2,11 @@ fn main() {
     let proto = "proto/grpc/testing/test.proto";
 
     tonic_prost_build::compile_protos(proto).unwrap();
+    tonic_protobuf_build::CodeGen::new()
+        .include("proto/grpc/testing")
+        .inputs(["test.proto", "empty.proto", "messages.proto"])
+        .compile()
+        .unwrap();
 
     // prevent needing to rebuild if files (or deps) haven't changed
     println!("cargo:rerun-if-changed={proto}");