From 8985eb9c757610aa94353573d73296ab8471a5e2 Mon Sep 17 00:00:00 2001
From: Jeff Hwang <jaehwang@squareup.com>
Date: Tue, 19 Aug 2025 13:59:04 -0400
Subject: [PATCH] add service name

---
 .../client/EnvoyCallbackConnectorProvider.kt  |  7 ++++---
 .../client/GrpcCallbackConnectorProvider.kt   |  2 ++
 .../client/HttpCallbackConnectorProvider.kt   |  1 +
 .../client/ServiceNameHeaderInterceptor.kt    | 21 +++++++++++++++++++
 4 files changed, 28 insertions(+), 3 deletions(-)
 create mode 100644 service/src/main/kotlin/app/cash/backfila/client/ServiceNameHeaderInterceptor.kt

diff --git a/service/src/main/kotlin/app/cash/backfila/client/EnvoyCallbackConnectorProvider.kt b/service/src/main/kotlin/app/cash/backfila/client/EnvoyCallbackConnectorProvider.kt
index 892f38a72..59d6967a5 100644
--- a/service/src/main/kotlin/app/cash/backfila/client/EnvoyCallbackConnectorProvider.kt
+++ b/service/src/main/kotlin/app/cash/backfila/client/EnvoyCallbackConnectorProvider.kt
@@ -58,11 +58,12 @@ class EnvoyCallbackConnectorProvider @Inject constructor(
     val httpClientEndpointConfig = httpClientsConfig[baseUrl]
 
     var okHttpClient = httpClientFactory.create(httpClientEndpointConfig)
+    val okHttpClientBuilder = okHttpClient.newBuilder()
+    okHttpClientBuilder.addInterceptor(ServiceNameHeaderInterceptor(serviceName))
     if (!headers.isNullOrEmpty()) {
-      okHttpClient = okHttpClient.newBuilder()
-        .addInterceptor(OkHttpClientSpecifiedHeadersInterceptor(headers))
-        .build()
+      okHttpClientBuilder.addInterceptor(OkHttpClientSpecifiedHeadersInterceptor(headers))
     }
+    okHttpClient = okHttpClientBuilder.build()
 
     val retrofit = Retrofit.Builder()
       .baseUrl(baseUrl)
diff --git a/service/src/main/kotlin/app/cash/backfila/client/GrpcCallbackConnectorProvider.kt b/service/src/main/kotlin/app/cash/backfila/client/GrpcCallbackConnectorProvider.kt
index fa84d3cf1..c7aed4a74 100644
--- a/service/src/main/kotlin/app/cash/backfila/client/GrpcCallbackConnectorProvider.kt
+++ b/service/src/main/kotlin/app/cash/backfila/client/GrpcCallbackConnectorProvider.kt
@@ -53,6 +53,8 @@ class GrpcCallbackConnectorProvider @Inject constructor(
     val baseUrl = httpClientConfigUrlProvider.getUrl(httpClientEndpointConfig)
 
     val okHttpClientBuilder = httpClientFactory.create(httpClientEndpointConfig).newBuilder()
+
+    okHttpClientBuilder.addInterceptor(ServiceNameHeaderInterceptor(serviceName))
     if (!headers.isNullOrEmpty()) {
       okHttpClientBuilder.addInterceptor(OkHttpClientSpecifiedHeadersInterceptor(headers))
     }
diff --git a/service/src/main/kotlin/app/cash/backfila/client/HttpCallbackConnectorProvider.kt b/service/src/main/kotlin/app/cash/backfila/client/HttpCallbackConnectorProvider.kt
index 5b861db41..d2be6bf7e 100644
--- a/service/src/main/kotlin/app/cash/backfila/client/HttpCallbackConnectorProvider.kt
+++ b/service/src/main/kotlin/app/cash/backfila/client/HttpCallbackConnectorProvider.kt
@@ -57,6 +57,7 @@ class HttpCallbackConnectorProvider @Inject constructor(
           addNetworkInterceptor(it)
         }
       }
+    okHttpClientBuilder.addInterceptor(ServiceNameHeaderInterceptor(serviceName))
     if (!headers.isNullOrEmpty()) {
       okHttpClientBuilder.addInterceptor(OkHttpClientSpecifiedHeadersInterceptor(headers))
     }
diff --git a/service/src/main/kotlin/app/cash/backfila/client/ServiceNameHeaderInterceptor.kt b/service/src/main/kotlin/app/cash/backfila/client/ServiceNameHeaderInterceptor.kt
new file mode 100644
index 000000000..566306b6b
--- /dev/null
+++ b/service/src/main/kotlin/app/cash/backfila/client/ServiceNameHeaderInterceptor.kt
@@ -0,0 +1,21 @@
+package app.cash.backfila.client
+
+import okhttp3.Interceptor
+import okhttp3.Response
+
+/**
+ * Adds service name header to HTTP requests for service identification.
+ * This allows downstream systems to identify which service made the request.
+ */
+class ServiceNameHeaderInterceptor(
+  private val serviceName: String,
+) : Interceptor {
+  override fun intercept(chain: Interceptor.Chain): Response {
+    val request = chain.request()
+      .newBuilder()
+      .header("X-Forwarded-Service", serviceName)
+      .build()
+
+    return chain.proceed(request)
+  }
+}