From 08a0ca09162c367384cac0995af99db3cb28235d Mon Sep 17 00:00:00 2001
From: Matthew Wear <matthew.wear@gmail.com>
Date: Wed, 7 Oct 2020 17:38:34 -0700
Subject: [PATCH] chore!: remove duplicate hostname resource attribute

---
 .../resource/detectors/google_cloud_platform.rb     | 13 +++++++------
 .../detectors/google_cloud_platform_test.rb         |  1 -
 sdk/lib/opentelemetry/sdk/resources/constants.rb    |  4 ----
 3 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/resource_detectors/lib/opentelemetry/resource/detectors/google_cloud_platform.rb b/resource_detectors/lib/opentelemetry/resource/detectors/google_cloud_platform.rb
index 95ab24eac..dbcef2cf1 100644
--- a/resource_detectors/lib/opentelemetry/resource/detectors/google_cloud_platform.rb
+++ b/resource_detectors/lib/opentelemetry/resource/detectors/google_cloud_platform.rb
@@ -13,7 +13,7 @@ module Detectors
       module GoogleCloudPlatform
         extend self
 
-        def detect # rubocop:disable Metrics/AbcSize
+        def detect # rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/MethodLength
           gcp_env = Google::Cloud::Env.new
           resource_attributes = {}
           resource_constants = OpenTelemetry::SDK::Resources::Constants
@@ -24,15 +24,16 @@ def detect # rubocop:disable Metrics/AbcSize
             resource_attributes[resource_constants::CLOUD_RESOURCE[:region]] = gcp_env.instance_attribute('cluster-location')
             resource_attributes[resource_constants::CLOUD_RESOURCE[:zone]] = gcp_env.instance_zone
 
-            resource_attributes[resource_constants::HOST_RESOURCE[:hostname]] = hostname
             resource_attributes[resource_constants::HOST_RESOURCE[:id]] = gcp_env.lookup_metadata('instance', 'id')
-            resource_attributes[resource_constants::HOST_RESOURCE[:name]] = gcp_env.lookup_metadata('instance', 'hostname')
+            resource_attributes[resource_constants::HOST_RESOURCE[:name]] = ENV['HOSTNAME'] ||
+                                                                            gcp_env.lookup_metadata('instance', 'hostname') ||
+                                                                            safe_gethostname
           end
 
           if gcp_env.kubernetes_engine?
             resource_attributes[resource_constants::K8S_RESOURCE[:cluster_name]] = gcp_env.instance_attribute('cluster-name')
             resource_attributes[resource_constants::K8S_RESOURCE[:namespace_name]] = gcp_env.kubernetes_engine_namespace_id
-            resource_attributes[resource_constants::K8S_RESOURCE[:pod_name]] = hostname
+            resource_attributes[resource_constants::K8S_RESOURCE[:pod_name]] = ENV['HOSTNAME'] || safe_gethostname
 
             resource_attributes[resource_constants::CONTAINER_RESOURCE[:name]] = ENV['CONTAINER_NAME']
           end
@@ -43,8 +44,8 @@ def detect # rubocop:disable Metrics/AbcSize
 
         private
 
-        def hostname
-          ENV['HOSTNAME'] || Socket.gethostname
+        def safe_gethostname
+          Socket.gethostname
         rescue StandardError
           ''
         end
diff --git a/resource_detectors/test/opentelemetry/detectors/google_cloud_platform_test.rb b/resource_detectors/test/opentelemetry/detectors/google_cloud_platform_test.rb
index f2cede721..0e026f914 100644
--- a/resource_detectors/test/opentelemetry/detectors/google_cloud_platform_test.rb
+++ b/resource_detectors/test/opentelemetry/detectors/google_cloud_platform_test.rb
@@ -51,7 +51,6 @@
           'cloud.account.id' => 'opentelemetry',
           'cloud.region' => 'us-central1',
           'cloud.zone' => 'us-central1-a',
-          'host.hostname' => 'opentelemetry-test',
           'host.id' => 'opentelemetry-test',
           'host.name' => 'opentelemetry-test',
           'k8s.cluster.name' => 'opentelemetry-cluster',
diff --git a/sdk/lib/opentelemetry/sdk/resources/constants.rb b/sdk/lib/opentelemetry/sdk/resources/constants.rb
index 6f7637292..6182f53b4 100644
--- a/sdk/lib/opentelemetry/sdk/resources/constants.rb
+++ b/sdk/lib/opentelemetry/sdk/resources/constants.rb
@@ -79,10 +79,6 @@ module Constants
 
         # Attributes defining a computing instance (e.g. host).
         HOST_RESOURCE = {
-          # Hostname of the host. It contains what the hostname command returns on the
-          # host machine.
-          hostname: 'host.hostname',
-
           # Unique host id. For Cloud this must be the instance_id assigned by the
           # cloud provider
           id: 'host.id',