Add x-restate-server header in responses

build.gradle.kts

@@ -24,7 +24,7 @@ allprojects {
 
   configure<com.diffplug.gradle.spotless.SpotlessExtension> {
     java {
-      targetExclude("build/generated/**/*.java")
+      targetExclude("build/**/*.java")
 
       googleJavaFormat()
 

sdk-common/build.gradle.kts

@@ -16,3 +16,67 @@ dependencies {
   testImplementation(testingLibs.junit.jupiter)
   testImplementation(testingLibs.assertj)
 }
+
+val generatedVersionDir = layout.buildDirectory.dir("version")
+
+generatedVersionDir.get().asFile.mkdirs()
+
+sourceSets { main { java { srcDir(generatedVersionDir) } } }
+
+// Configure generation of version class
+
+// From https://discuss.kotlinlang.org/t/use-git-hash-as-version-number-in-build-gradle-kts/19818/4
+fun String.runCommand(
+    workingDir: File = File("."),
+    timeoutAmount: Long = 5,
+    timeoutUnit: TimeUnit = TimeUnit.SECONDS
+): String =
+    ProcessBuilder(split("\\s(?=(?:[^'\"`]*(['\"`])[^'\"`]*\\1)*[^'\"`]*$)".toRegex()))
+        .directory(workingDir)
+        .redirectOutput(ProcessBuilder.Redirect.PIPE)
+        .redirectError(ProcessBuilder.Redirect.PIPE)
+        .start()
+        .apply { waitFor(timeoutAmount, timeoutUnit) }
+        .run {
+          val error = errorStream.bufferedReader().readText().trim()
+          if (error.isNotEmpty()) {
+            throw IllegalStateException(error)
+          }
+          inputStream.bufferedReader().readText().trim()
+        }
+
+val generateVersionClass =
+    tasks.register("generateVersionClass") {
+      dependsOn(project.tasks.processResources)
+      outputs.dir(generatedVersionDir)
+
+      doFirst {
+        val gitHash = "git rev-parse --short=8 HEAD".runCommand(workingDir = rootDir)
+        val containingDir = generatedVersionDir.get().dir("dev/restate/sdk/version").asFile
+        assert(containingDir.exists() || containingDir.mkdirs())
+
+        file("$containingDir/Version.java")
+            .writeText(
+                """
+      package dev.restate.sdk.version;
+
+      public final class Version {
+          private Version() {}
+
+          public static final String VERSION = "$version";
+          public static final String GIT_HASH = "$gitHash";
+          public static final String X_RESTATE_SERVER = "restate-sdk-java/" + VERSION + "_" + GIT_HASH;
+      }
+      """
+                    .trimIndent())
+
+        check(file("${projectDir}/build/version/dev/restate/sdk/version/Version.java").exists()) {
+          "${projectDir}/build/version/dev/restate/sdk/version/Version.java doesn't exist?!"
+        }
+      }
+    }
+
+tasks {
+  withType<JavaCompile>().configureEach { dependsOn(generateVersionClass) }
+  withType<Jar>().configureEach { dependsOn(generateVersionClass) }
+}

sdk-core/build.gradle.kts

@@ -1,5 +1,3 @@
-import com.google.protobuf.gradle.id
-
 plugins {
   `java-library`
   `library-publishing-conventions`

sdk-http-vertx/src/main/java/dev/restate/sdk/http/vertx/RequestHttpServerHandler.java

@@ -18,6 +18,7 @@
 import dev.restate.sdk.core.ResolvedEndpointHandler;
 import dev.restate.sdk.core.RestateEndpoint;
 import dev.restate.sdk.core.manifest.DeploymentManifestSchema;
+import dev.restate.sdk.version.Version;
 import io.netty.util.AsciiString;
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.context.propagation.TextMapGetter;
@@ -41,6 +42,9 @@ class RequestHttpServerHandler implements Handler<HttpServerRequest> {
   private static final Logger LOG = LogManager.getLogger(RequestHttpServerHandler.class);
 
   private static final AsciiString APPLICATION_RESTATE = AsciiString.cached("application/restate");
+  private static final AsciiString X_RESTATE_SERVER_KEY = AsciiString.cached("x-restate-server");
+  private static final AsciiString X_RESTATE_SERVER_VALUE =
+      AsciiString.cached(Version.X_RESTATE_SERVER);
   private static final ObjectMapper MANIFEST_OBJECT_MAPPER = new ObjectMapper();
 
   private static final Pattern SLASH = Pattern.compile(Pattern.quote("/"));
@@ -127,7 +131,9 @@ public void handle(HttpServerRequest request) {
     // Vert.x will send them as soon as we send the first write
     HttpServerResponse response = request.response();
     response.setStatusCode(OK.code());
-    response.putHeader(CONTENT_TYPE, APPLICATION_RESTATE);
+    response
+        .putHeader(CONTENT_TYPE, APPLICATION_RESTATE)
+        .putHeader(X_RESTATE_SERVER_KEY, X_RESTATE_SERVER_VALUE);
     // This is No-op for HTTP2
     response.setChunked(true);
 
@@ -159,6 +165,7 @@ private void handleDiscoveryRequest(HttpServerRequest request) {
     request
         .response()
         .setStatusCode(OK.code())
+        .putHeader(X_RESTATE_SERVER_KEY, X_RESTATE_SERVER_VALUE)
         .putHeader(CONTENT_TYPE, APPLICATION_JSON)
         .end(responseBuffer);
   }

sdk-lambda/src/main/java/dev/restate/sdk/lambda/RestateLambdaEndpoint.java

@@ -19,6 +19,7 @@
 import dev.restate.sdk.core.ResolvedEndpointHandler;
 import dev.restate.sdk.core.RestateEndpoint;
 import dev.restate.sdk.core.manifest.DeploymentManifestSchema;
+import dev.restate.sdk.version.Version;
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.context.propagation.TextMapGetter;
 import java.nio.ByteBuffer;
@@ -39,9 +40,9 @@ public final class RestateLambdaEndpoint {
   private static final String INVOKE_PATH_SEGMENT = "invoke";
   private static final String DISCOVER_PATH = "/discover";
   private static final Map<String, String> INVOKE_RESPONSE_HEADERS =
-      Map.of("content-type", "application/restate");
+      Map.of("content-type", "application/restate", "x-restate-server", Version.X_RESTATE_SERVER);
   private static final Map<String, String> DISCOVER_RESPONSE_HEADERS =
-      Map.of("content-type", "application/json");
+      Map.of("content-type", "application/json", "x-restate-server", Version.X_RESTATE_SERVER);
 
   private static TextMapGetter<Map<String, String>> OTEL_HEADERS_GETTER =
       new TextMapGetter<>() {