Fixed Kubernetes Engine names in some methods, and implemented an alt…

…ernate mechanism to get the kubernetes namespace (googleapis#2071)

google-cloud-env/lib/google/cloud/env.rb

@@ -25,7 +25,7 @@ module Cloud
     # This library provides access to information about the application's
     # hosting environment if it is running on Google Cloud Platform. You may
     # use this library to determine which Google Cloud product is hosting your
-    # application (e.g. app engine, container engine), information about the
+    # application (e.g. App Engine, Kubernetes Engine), information about the
     # Google Cloud project hosting the application, information about the
     # virtual machine instance, authentication information, and so forth.
     #
@@ -87,13 +87,15 @@ def app_engine?
       end
 
       ##
-      # Determine whether the application is running on Google Container Engine.
+      # Determine whether the application is running on Google Kubernetes
+      # Engine (GKE).
       #
       # @return [Boolean]
       #
-      def container_engine?
-        container_engine_cluster_name ? true : false
+      def kubernetes_engine?
+        kubernetes_engine_cluster_name ? true : false
       end
+      alias container_engine? kubernetes_engine?
 
       ##
       # Determine whether the application is running on Google Cloud Shell.
@@ -107,7 +109,7 @@ def cloud_shell?
       ##
       # Determine whether the application is running on Google Compute Engine.
       #
-      # Note that most other products (e.g. App Engine, Container Engine,
+      # Note that most other products (e.g. App Engine, Kubernetes Engine,
       # Cloud Shell) themselves use Compute Engine under the hood, so this
       # method will return true for all the above products. If you want to
       # determine whether the application is running on a "raw" Compute Engine
@@ -123,12 +125,12 @@ def compute_engine?
       ##
       # Determine whether the application is running on "raw" Google Compute
       # Engine without using a higher level hosting product such as App
-      # Engine or Container Engine.
+      # Engine or Kubernetes Engine.
       #
       # @return [Boolean]
       #
       def raw_compute_engine?
-        !app_engine? && !cloud_shell? && metadata? && !container_engine?
+        !app_engine? && !cloud_shell? && metadata? && !kubernetes_engine?
       end
 
       ##
@@ -273,26 +275,36 @@ def app_engine_memory_mb
       end
 
       ##
-      # Returns the name of the Container Engine cluster hosting the
+      # Returns the name of the Kubernetes Engine cluster hosting the
       # application, or `nil` if the current code is not running in
-      # Container Engine.
+      # Kubernetes Engine.
       #
       # @return [String,nil]
       #
-      def container_engine_cluster_name
+      def kubernetes_engine_cluster_name
         instance_attribute "cluster-name"
       end
+      alias container_engine_cluster_name kubernetes_engine_cluster_name
 
       ##
-      # Returns the name of the Container Engine namespace hosting the
+      # Returns the name of the Kubernetes Engine namespace hosting the
       # application, or `nil` if the current code is not running in
-      # Container Engine.
+      # Kubernetes Engine.
       #
       # @return [String,nil]
       #
-      def container_engine_namespace_id
-        env["GKE_NAMESPACE_ID"]
+      def kubernetes_engine_namespace_id
+        # The Kubernetes namespace is difficult to obtain without help from
+        # the application using the Downward API. The environment variable
+        # below is set in some older versions of GKE, and the file below is
+        # present in Kubernetes as of version 1.9, but it is possible that
+        # alternatives will need to be found in the future.
+        env["GKE_NAMESPACE_ID"] ||
+          ::IO.read("/var/run/secrets/kubernetes.io/serviceaccount/namespace")
+      rescue SystemCallError
+        nil
       end
+      alias container_engine_namespace_id kubernetes_engine_namespace_id
 
       ##
       # Determine whether the Google Compute Engine Metadata Service is running.

google-cloud-env/test/google/cloud/env_test.rb

@@ -112,7 +112,7 @@ def gce_stubs
     env = ::Google::Cloud::Env.new env: gae_env, connection: gce_conn
 
     env.app_engine?.must_equal true
-    env.container_engine?.must_equal false
+    env.kubernetes_engine?.must_equal false
     env.cloud_shell?.must_equal false
     env.compute_engine?.must_equal true
     env.raw_compute_engine?.must_equal false
@@ -128,15 +128,15 @@ def gce_stubs
     env.app_engine_service_version.must_equal gae_version
     env.app_engine_memory_mb.must_equal gae_memory_mb
 
-    env.container_engine_cluster_name.must_be_nil
-    env.container_engine_namespace_id.must_be_nil
+    env.kubernetes_engine_cluster_name.must_be_nil
+    env.kubernetes_engine_namespace_id.must_be_nil
   end
 
-  it "returns correct values when running on container engine" do
+  it "returns correct values when running on kubernetes engine" do
     env = ::Google::Cloud::Env.new env: gke_env, connection: gke_conn
 
     env.app_engine?.must_equal false
-    env.container_engine?.must_equal true
+    env.kubernetes_engine?.must_equal true
     env.cloud_shell?.must_equal false
     env.compute_engine?.must_equal true
     env.raw_compute_engine?.must_equal false
@@ -152,15 +152,15 @@ def gce_stubs
     env.app_engine_service_version.must_be_nil
     env.app_engine_memory_mb.must_be_nil
 
-    env.container_engine_cluster_name.must_equal gke_cluster
-    env.container_engine_namespace_id.must_equal gke_namespace
+    env.kubernetes_engine_cluster_name.must_equal gke_cluster
+    env.kubernetes_engine_namespace_id.must_equal gke_namespace
   end
 
   it "returns correct values when running on cloud shell" do
     env = ::Google::Cloud::Env.new env: cloud_shell_env, connection: gce_conn
 
     env.app_engine?.must_equal false
-    env.container_engine?.must_equal false
+    env.kubernetes_engine?.must_equal false
     env.cloud_shell?.must_equal true
     env.compute_engine?.must_equal true
     env.raw_compute_engine?.must_equal false
@@ -176,15 +176,15 @@ def gce_stubs
     env.app_engine_service_version.must_be_nil
     env.app_engine_memory_mb.must_be_nil
 
-    env.container_engine_cluster_name.must_be_nil
-    env.container_engine_namespace_id.must_be_nil
+    env.kubernetes_engine_cluster_name.must_be_nil
+    env.kubernetes_engine_namespace_id.must_be_nil
   end
 
   it "returns correct values when running on compute engine" do
     env = ::Google::Cloud::Env.new env: gce_env, connection: gce_conn
 
     env.app_engine?.must_equal false
-    env.container_engine?.must_equal false
+    env.kubernetes_engine?.must_equal false
     env.cloud_shell?.must_equal false
     env.compute_engine?.must_equal true
     env.raw_compute_engine?.must_equal true
@@ -200,15 +200,15 @@ def gce_stubs
     env.app_engine_service_version.must_be_nil
     env.app_engine_memory_mb.must_be_nil
 
-    env.container_engine_cluster_name.must_be_nil
-    env.container_engine_namespace_id.must_be_nil
+    env.kubernetes_engine_cluster_name.must_be_nil
+    env.kubernetes_engine_namespace_id.must_be_nil
   end
 
   it "returns correct values when not running on gcp" do
     env = ::Google::Cloud::Env.new env: ext_env, connection: ext_conn
 
     env.app_engine?.must_equal false
-    env.container_engine?.must_equal false
+    env.kubernetes_engine?.must_equal false
     env.cloud_shell?.must_equal false
     env.compute_engine?.must_equal false
     env.raw_compute_engine?.must_equal false
@@ -224,8 +224,8 @@ def gce_stubs
     env.app_engine_service_version.must_be_nil
     env.app_engine_memory_mb.must_be_nil
 
-    env.container_engine_cluster_name.must_be_nil
-    env.container_engine_namespace_id.must_be_nil
+    env.kubernetes_engine_cluster_name.must_be_nil
+    env.kubernetes_engine_namespace_id.must_be_nil
   end
 
 end