feat: Provide a query for whether a logging agent is expected in the …

…current environment

lib/google/cloud/env.rb

@@ -497,6 +497,19 @@ def kubernetes_engine_namespace_id
       end
       alias container_engine_namespace_id kubernetes_engine_namespace_id
 
+      ##
+      # Determine whether the application is running in an environment where a
+      # Google Cloud logging agent is expected to be running. In such an
+      # environment, we expect that the standard output and error streams are
+      # likely to be parsed by the logging agent and log entries are written to
+      # the Google Cloud Logging service.
+      #
+      # @return [boolean]
+      #
+      def logging_agent_expected?
+        compute_engine? && !cloud_shell? && (app_engine? || knative? || kubernetes_engine?)
+      end
+
       ##
       # Returns the global instance of {Google::Cloud::Env}.
       #

test/google/cloud/env_test.rb

@@ -160,6 +160,7 @@ def ext_conn failure_count: 0
     _(env.cloud_shell?).must_equal false
     _(env.compute_engine?).must_equal true
     _(env.raw_compute_engine?).must_equal false
+    _(env.logging_agent_expected?).must_equal true
 
     _(env.project_id).must_equal project_id
     _(env.numeric_project_id).must_equal numeric_project_id
@@ -189,6 +190,7 @@ def ext_conn failure_count: 0
     _(env.cloud_shell?).must_equal false
     _(env.compute_engine?).must_equal true
     _(env.raw_compute_engine?).must_equal false
+    _(env.logging_agent_expected?).must_equal true
 
     _(env.project_id).must_equal project_id
     _(env.numeric_project_id).must_equal numeric_project_id
@@ -218,6 +220,7 @@ def ext_conn failure_count: 0
     _(env.cloud_shell?).must_equal false
     _(env.compute_engine?).must_equal true
     _(env.raw_compute_engine?).must_equal false
+    _(env.logging_agent_expected?).must_equal true
 
     _(env.project_id).must_equal project_id
     _(env.numeric_project_id).must_equal numeric_project_id
@@ -247,6 +250,7 @@ def ext_conn failure_count: 0
     _(env.cloud_shell?).must_equal false
     _(env.compute_engine?).must_equal true
     _(env.raw_compute_engine?).must_equal false
+    _(env.logging_agent_expected?).must_equal true
 
     _(env.project_id).must_equal project_id
     _(env.numeric_project_id).must_equal numeric_project_id
@@ -276,6 +280,7 @@ def ext_conn failure_count: 0
     _(env.cloud_shell?).must_equal true
     _(env.compute_engine?).must_equal true
     _(env.raw_compute_engine?).must_equal false
+    _(env.logging_agent_expected?).must_equal false
 
     _(env.project_id).must_equal project_id
     _(env.numeric_project_id).must_be_nil
@@ -292,7 +297,7 @@ def ext_conn failure_count: 0
     _(env.kubernetes_engine_namespace_id).must_be_nil
   end
 
-  it "returns correct values when running on compute engine" do
+  it "returns correct values when running on raw compute engine" do
     env.variables.backing_data = gce_variables
     env.compute_smbios.override_product_name = "Google"
     env.compute_metadata.overrides = gce_metadata_overrides
@@ -305,6 +310,7 @@ def ext_conn failure_count: 0
     _(env.cloud_shell?).must_equal false
     _(env.compute_engine?).must_equal true
     _(env.raw_compute_engine?).must_equal true
+    _(env.logging_agent_expected?).must_equal false
 
     _(env.project_id).must_equal project_id
     _(env.numeric_project_id).must_equal numeric_project_id
@@ -334,6 +340,7 @@ def ext_conn failure_count: 0
     _(env.cloud_shell?).must_equal false
     _(env.compute_engine?).must_equal false
     _(env.raw_compute_engine?).must_equal false
+    _(env.logging_agent_expected?).must_equal false
 
     _(env.project_id).must_be_nil
     _(env.numeric_project_id).must_be_nil