Revert "Revert "Preprocess application package in temp dir, then move atomically to d…""

1 files changed, 25 insertions, 10 deletions

diff --git a/config-application-package/src/main/java/com/yahoo/config/model/application/provider/FilesApplicationPackage.java b/config-application-package/src/main/java/com/yahoo/config/model/application/provider/FilesApplicationPackage.java
index 28bf8e10a93..df62f762c40 100644
--- a/config-application-package/src/main/java/com/yahoo/config/model/application/provider/FilesApplicationPackage.java
+++ b/config-application-package/src/main/java/com/yahoo/config/model/application/provider/FilesApplicationPackage.java
@@ -52,6 +52,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.Reader;
 import java.io.StringReader;
+import java.nio.file.AccessDeniedException;
 import java.nio.file.Files;
 import java.security.MessageDigest;
 import java.util.ArrayList;
@@ -613,24 +614,38 @@ public class FilesApplicationPackage extends AbstractApplicationPackage {
 
     @Override
     public ApplicationPackage preprocess(Zone zone, DeployLogger logger) throws IOException {
-        IOUtils.recursiveDeleteDir(preprocessedDir);
-        IOUtils.copyDirectory(appDir, preprocessedDir, -1,
+        try {
+            java.nio.file.Path tempDir = Files.createTempDirectory(appDir.getParentFile().toPath(), "preprocess-tempdir");
+            preprocess(appDir, tempDir.toFile(), zone);
+            IOUtils.recursiveDeleteDir(preprocessedDir);
+            // Use 'move' to make sure we do this atomically, important to avoid writing only partial content e.g.
+            // when shutting down.
+            // Temp directory needs to be on the same file system as appDir for 'move' to work,
+            // if it fails (with DirectoryNotEmptyException (!)) we need to use 'copy' instead
+            // (this will always be the case for the application package for a standalone container).
+            Files.move(tempDir, preprocessedDir.toPath());
+        } catch (AccessDeniedException e) {
+            preprocess(appDir, preprocessedDir, zone);
+        }
+        FilesApplicationPackage preprocessedApp = fromFile(preprocessedDir, includeSourceFiles);
+        preprocessedApp.copyUserDefsIntoApplication();
+        return preprocessedApp;
+    }
+
+    private void preprocess(File appDir, File dir, Zone zone) throws IOException {
+        validateServicesFile();
+        IOUtils.copyDirectory(appDir, dir, - 1,
                               (__, name) -> ! List.of(preprocessed, SERVICES, HOSTS, CONFIG_DEFINITIONS_DIR).contains(name));
-        File servicesFile = validateServicesFile();
-        preprocessXML(applicationFile(preprocessedDir, SERVICES), servicesFile, zone);
-        preprocessXML(applicationFile(preprocessedDir, HOSTS), getHostsFile(), zone);
-        FilesApplicationPackage preprocessed = fromFile(preprocessedDir, includeSourceFiles);
-        preprocessed.copyUserDefsIntoApplication();
-        return preprocessed;
+        preprocessXML(applicationFile(dir, SERVICES), getServicesFile(), zone);
+        preprocessXML(applicationFile(dir, HOSTS), getHostsFile(), zone);
     }
 
-    private File validateServicesFile() throws IOException {
+    private void validateServicesFile() throws IOException {
         File servicesFile = getServicesFile();
         if ( ! servicesFile.exists())
             throw new IllegalArgumentException(SERVICES + " does not exist in application package");
         if (IOUtils.readFile(servicesFile).isEmpty())
             throw new IllegalArgumentException(SERVICES + " in application package is empty");
-        return servicesFile;
     }
 
     private void copyUserDefsIntoApplication() {