From db529b7eeeef506ac6c4f0209e0ddf8f59b2743f Mon Sep 17 00:00:00 2001
From: Siim Kallas <siimkallas@gmail.com>
Date: Mon, 7 Jun 2021 15:49:30 +0300
Subject: [PATCH] fix: service name precedence

---
 src/options.ts       | 32 +++++++++++++-------------------
 test/options.test.ts |  2 +-
 2 files changed, 14 insertions(+), 20 deletions(-)

diff --git a/src/options.ts b/src/options.ts
index 90113b08..d658baa1 100644
--- a/src/options.ts
+++ b/src/options.ts
@@ -82,17 +82,25 @@ export function _setDefaultOptions(options: Partial<Options> = {}): Options {
     options.logInjectionEnabled = getEnvBoolean('SPLUNK_LOGS_INJECTION', false);
   }
 
-  options.serviceName =
-    options.serviceName || env.SPLUNK_SERVICE_NAME || defaultServiceName;
   options.endpoint =
     options.endpoint || env.OTEL_EXPORTER_JAEGER_ENDPOINT || defaultEndpoint;
 
   const extraTracerConfig = options.tracerConfig || {};
 
+  const resource = new EnvResourceDetector().detect();
+
+  options.serviceName =
+    options.serviceName ||
+    env.SPLUNK_SERVICE_NAME ||
+    resource.attributes[ResourceAttributes.SERVICE_NAME]?.toString() ||
+    defaultServiceName;
+
   const tracerConfig = {
-    resource: configureResource({
-      serviceName: options.serviceName,
-    }),
+    resource: resource.merge(
+      new Resource({
+        [ResourceAttributes.SERVICE_NAME]: options.serviceName,
+      })
+    ),
     ...extraTracerConfig,
   };
 
@@ -168,17 +176,3 @@ function getEnvBoolean(key: string, defaultValue = true) {
 
   return true;
 }
-
-function configureResource(options: { serviceName: string }): Resource {
-  const resource = new EnvResourceDetector().detect();
-
-  if (resource.attributes[ResourceAttributes.SERVICE_NAME] !== undefined) {
-    return resource;
-  }
-
-  return resource.merge(
-    new Resource({
-      [ResourceAttributes.SERVICE_NAME]: options.serviceName,
-    })
-  );
-}
diff --git a/test/options.test.ts b/test/options.test.ts
index 42b8a324..b2758b84 100644
--- a/test/options.test.ts
+++ b/test/options.test.ts
@@ -105,7 +105,7 @@ describe('options', () => {
     });
   });
 
-  it('prefers resource information loaded from the environment', () => {
+  it('prefers service name from env resource info over the default service name', () => {
     process.env.OTEL_RESOURCE_ATTRIBUTES = 'service.name=foobar';
     const options = _setDefaultOptions();
     delete process.env.OTEL_RESOURCE_ATTRIBUTES;