Fix OVERWRITE option bug when source file is symlink and destination file exists

Author: americanomin

lib/instance_agent/plugins/codedeploy/install_instruction.rb

@@ -232,7 +232,7 @@ def execute(cleanup_file)
           # the CopyCommand entry should not even be created by Installer
           cleanup_file.puts(@destination)
           if File.symlink?(@source)
-            FileUtils.symlink(File.readlink(@source), @destination)
+            FileUtils.symlink(File.readlink(@source), @destination, :force => true)
           else
             FileUtils.copy(@source, @destination, :preserve => true)
           end

lib/instance_agent/plugins/codedeploy/installer.rb

@@ -123,6 +123,9 @@ def generate_normal_copy(i, absolute_source_path, destination)
             when "DISALLOW"
               raise "The deployment failed because a specified file already exists at this location: #{destination}"
             when "OVERWRITE"
+              if File.directory?(destination)
+                raise "The deployment failed because a directory already exists at this location: #{destination}"
+              end
               i.copy(absolute_source_path, destination)
             when "RETAIN"
               # neither generate copy command or fail the deployment

test/instance_agent/plugins/codedeploy/installer_test.rb

@@ -157,17 +157,31 @@ class CodeDeployPluginInstallerTest < InstanceAgentTestCase
             end
           end
 
-          should "generate a copy command if the file already exists and @file_exists_behavior is set to 'OVERWRITE'" do
-            @app_spec
-              .stubs(:files)
-              .returns([stub(:source => "src1",
-                             :destination => "dst1")])
-            File.stubs(:exists?).with("dst1/src1").returns(true)
-            @instruction_builder
-              .expects(:copy)
-              .with("deploy-archive-dir/src1", "dst1/src1")
-            @installer.file_exists_behavior = "OVERWRITE"
-            @installer.install(@deployment_group_id, @app_spec)
+          context "if the file already exists and @file_exists_behavior is set to 'OVERWRITE'" do
+            setup do
+              @app_spec
+                  .stubs(:files)
+                  .returns([stub(:source => "src1",
+                                 :destination => "dst1")])
+              File.stubs(:exists?).with("dst1/src1").returns(true)
+              @installer.file_exists_behavior = "OVERWRITE"
+            end
+
+            should "generate a copy command if destination is regular file" do
+              File.stubs(:directory?).with("dst1/src1").returns(false)
+              @instruction_builder
+                  .expects(:copy)
+                  .with("deploy-archive-dir/src1", "dst1/src1")
+              @installer.install(@deployment_group_id, @app_spec)
+            end
+
+            should "raise an error if destination is directory" do
+              File.stubs(:directory?).with("dst1/src1").returns(true)
+              File.stubs(:symlink?).with("dst1/src1").returns(false)
+              assert_raised_with_message("The deployment failed because a directory already exists at this location: dst1/src1") do
+                @installer.install(@deployment_group_id, @app_spec)
+              end
+            end
           end
 
           should "neither generate a copy command nor raise an error if the file already exists and @file_exists_behavior is set to 'RETAIN'" do