Build a gRPC server with Tonic

Author: lquerel

protobuf-grpc.md

@@ -21,12 +21,63 @@ TBD
 
 ## Tonic
 Tonic is a crate implementing the gRPC protocol on top of HTTP/2 and Prost. 
-```shell
-cargo add tonic
+
+### Build a gRPC server with Tonic
+
+File hierarchy used for this section.
+
+```
+proto/
+  metrics/
+    v1/
+      metrics_service.proto
+  ...
+src/
+  lib.rs
+Cargo.toml
+build.rs
 ```
 
-### Build gRPC spec with Tonic
-TBD
+Add the following dependencies in Cargo.toml.
+
+```toml
+[dependencies]
+tonic = "0.5"
+prost = "0.8"
+
+[build-dependencies]
+tonic-build = "0.5"
+```
+
+Add the following `build.rs` file at the root level.
+
+```rust
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    tonic_build::configure().compile(
+        &[
+            "proto/metrics/v1/metrics_service.proto",
+            ...
+        ],
+        &["proto"],
+    )?;
+
+    Ok(())
+}
+```
+
+Declare the modules generated by Tonic in lib.rs
+
+```rust
+pub mod metrics {
+    pub mod proto {
+        pub mod v1 {
+            tonic::include_proto!("metrics.v1");
+        }
+    }
+    
+    ...
+}
+```
 
 ### Multiple instances of a gRPC service listening to the same port
 
@@ -58,4 +109,4 @@ Server::builder()
   .serve_with_incoming(incoming)
   .await
   .unwrap();
-```
+```