feat: allow http status endpoint for monitoring (#44)

Add `/health` URL which just returns OK with `200` code for health check
of the application.

Partially avoiding
#43

Author: vsarunas

README.md

@@ -90,6 +90,7 @@ Below, some compatible visualisation tools:
 
 - pprof's [`/debug/pprof/profile` endpoint](https://pkg.go.dev/net/http/pprof)
 - Swift Profile Recorder's own `/sample` endpoint
+- `/health` endpoint for health checks (returns `200 OK`)
 
 ## Example profiles
 

Sources/ProfileRecorderServer/Server.swift

@@ -585,6 +585,21 @@ public struct ProfileRecorderServer: Sendable {
                 ) != nil:
                 // Native Swift Profile Recorder Sampling server
                 sampleRequest = try JSONDecoder().decode(SampleRequest.self, from: request.body ?? ByteBuffer())
+            case (.GET, .some(let decodedURI))
+            where decodedURI.components.matches(prefix: [], oneOfPaths: [["health"]]) != nil:
+                // Health check endpoint
+                try await outbound.write(
+                    .head(
+                        HTTPResponseHead(
+                            version: .http1_1,
+                            status: .ok,
+                            headers: ["connection": "close"]
+                        )
+                    )
+                )
+                try await outbound.write(.body(ByteBuffer(string: "OK")))
+                try await outbound.write(.end(nil))
+                return
             case (let verb, .some(let decodedURI)):
                 let extraRouteHandlers = self.state.withLockedValue { state in
                     state.extraRouteHandlers

Tests/ProfileRecorderServerTests/ProfileRecorderServerTests.swift

@@ -58,6 +58,24 @@ final class ProfileRecorderServerTests: XCTestCase {
         }
     }
 
+    func testHealthEndpoint() async throws {
+        let server = ProfileRecorderServer(
+            configuration: try ProfileRecorderServerConfiguration.makeTCPListener(host: "127.0.0.1", port: 0)
+        )
+        try await server.withProfileRecordingServer(logger: Logger(label: "")) { server in
+            guard case .successful(let serverAddress) = server.startResult else {
+                XCTFail("failed to start server")
+                return
+            }
+
+            let response = try await HTTPClient.shared.get(
+                url: "http://127.0.0.1:\(serverAddress.port!)/health"
+            ).get()
+            XCTAssertEqual(.ok, response.status)
+            XCTAssertEqual(ByteBuffer(string: "OK"), response.body)
+        }
+    }
+
     func testUserExtraHandlerBasic() async throws {
         let server = ProfileRecorderServer(
             configuration: try ProfileRecorderServerConfiguration.makeTCPListener(host: "127.0.0.1", port: 0)