GoogleContainerTools/jib · error · NotDirectoryException

rootDir + " is not a directory"

Error message

rootDir + " is not a directory"

What it means

The DirectoryWalker constructor validates that the given rootDir is actually a directory before walking it. If Files.isDirectory(rootDir) is false, it throws NotDirectoryException('<rootDir> is not a directory'). Jib requires a real directory to enumerate layered files.

Source

Thrown at jib-core/src/main/java/com/google/cloud/tools/jib/filesystem/DirectoryWalker.java:42

import java.util.function.Predicate;
import java.util.stream.Stream;

/** Recursively applies a function to each file in a directory. */
public class DirectoryWalker {

  private final Path rootDir;

  private Predicate<Path> pathFilter = path -> true;

  /**
   * Initialize with a root directory to walk.
   *
   * @param rootDir the root directory.
   * @throws NotDirectoryException if the root directory is not a directory.
   */
  public DirectoryWalker(Path rootDir) throws NotDirectoryException {
    if (!Files.isDirectory(rootDir)) {
      throw new NotDirectoryException(rootDir + " is not a directory");
    }
    this.rootDir = rootDir;
  }

  /**
   * Adds a filter to the walked paths.
   *
   * @param pathFilter the filter. {@code pathFilter} returns {@code true} if the path should be
   *     accepted and {@code false} otherwise.
   * @return this
   */
  public DirectoryWalker filter(Predicate<Path> pathFilter) {
    this.pathFilter = this.pathFilter.and(pathFilter);
    return this;
  }

  /**
   * Filters away the {@code rootDir}.

View on GitHub (pinned to fb949e2676)

Solutions

1. Check the path in the message: confirm it exists and is a directory (ls -ld <path>)
2. Fix the configured path to point at the intended directory
3. Create the directory if it is missing (Files.createDirectories(path))
4. If you intended to include a single file, use a file-based layer/entry instead of DirectoryWalker

Example fix

// before
new DirectoryWalker(Path.of("config/app.yaml")); // NotDirectoryException
// after
Path dir = Path.of("config");
if (!Files.isDirectory(dir)) {
  throw new IllegalArgumentException("Expected a directory: " + dir);
}
new DirectoryWalker(dir);

// Java
if (!Files.isDirectory(rootDir)) {
  throw new IllegalArgumentException("Not a directory: " + rootDir);
}

static boolean isDirectoryOrNull(Path p) {
  return p != null && Files.isDirectory(p);
}
// use: if (isDirectoryOrNull(rootDir)) new DirectoryWalker(rootDir);

try {
  new DirectoryWalker(rootDir);
} catch (NotDirectoryException e) {
  throw new BadConfigException("Layer source must be a directory: " + e.getMessage(), e);
}

When it happens

Trigger: new DirectoryWalker(path) where path points to a regular file, a symlink target that is a file, or a nonexistent path (Files.isDirectory returns false for both).

Common situations: Configuring a jib layer's extra-files/directory to a file by mistake, typos in the configured path, or the path being deleted/replaced by a file before the build runs.

Related errors

• octalPermissions must be a 3-digit octal number (000-777)
• The class file (${jarEntry}) is of an invalid format.
• Reached end of class file (${jarEntry}) before being able to
• Invalid hash: ${hash}
• Invalid digest: ${digest}

AI-assisted analysis of GoogleContainerTools/jib@fb949e2676 (2026-09-06). Data as JSON: /api/errors/733be826de5482bf. Report an issue: GitHub.