public static boolean isDockerInstalled(Path dockerExecutable) {
    return Files.exists(dockerExecutable);
  }
Checks if Docker is installed on the user's system and by verifying if the executable path
provided has the appropriate permissions.

@param dockerExecutable path to the executable to test running
@return {@code true} if Docker is installed on the user's system and accessible
jib-core/src/main/java/com/google/cloud/tools/jib/docker/CliDockerClient.java