Why is this Change Important & Necessary?

Docker UI has been failing. The reason is that the tests run too fast. Look at the following snippet to see reason:

root@vagrant:/usr/local/submitty/config# stat autograding_containers.json 
  File: autograding_containers.json
  Size: 681       	Blocks: 8          IO Block: 4096   regular file
Device: fd00h/64768d	Inode: 2274614     Links: 1
Access: (0660/-rw-rw----)  Uid: ( 1001/submitty_php)   Gid: ( 1001/submitty_daemonphp)
Access: 2025-11-23 22:22:11.833514610 -0500
Modify: 2025-11-23 22:22:11.781514464 -0500
Change: 2025-11-23 22:22:11.781514464 -0500
 Birth: 2025-11-17 18:44:18.299287221 -0500
root@vagrant:/usr/local/submitty/config# fil^C
root@vagrant:/usr/local/submitty/config# stat /var/local/submitty/logs/docker/20251123.txt 
  File: /var/local/submitty/logs/docker/20251123.txt
  Size: 95008     	Blocks: 200        IO Block: 4096   regular file
Device: fd00h/64768d	Inode: 736155      Links: 1
Access: (0755/-rwxr-xr-x)  Uid: ( 1003/submitty_daemon)   Gid: ( 1001/submitty_daemonphp)
Access: 2025-11-23 22:22:11.513513716 -0500
Modify: 2025-11-23 22:22:11.029512364 -0500
Change: 2025-11-23 22:22:11.029512364 -0500
 Birth: 2025-11-23 22:12:50.427670218 -0500
root@vagrant:/usr/local/submitty/config#

Modify: 2025-11-23 22:22:11.781514464 -0500
Modify: 2025-11-23 22:22:11.029512364 -0500

With nanosecond precision, we can see this error clearly. However, PHP's filemtime stops at the seconds level, as shown by the code below

                $containers_mtime = filemtime($containers_config_path);
                $last_update_mtime = filemtime($last_update_logpath);

                echo "Containers mtime: " . $containers_mtime . "\n";
                echo "Last update mtime: " . $last_update_mtime . "\n";
                // If the containers config is older than or the same age as the last log, it's up to date.
                if ($containers_mtime <= $last_update_mtime) {
                    $this->update_needed = false;
                }

Containers mtime: 1763954531
Last update mtime: 1763954531

What is the New Behavior?

The most simple fix would be to change the docker test to introduce a one second delay. However, this would only fix the test and not the production grade issue that it can cause. However, since PHP does not have a built in function to get file time by the nanoseconds (if the operating system has nanoseconds in the first place), this would be pretty hard to implement. Furthermore, this should rarely pop up as instructors are usually not updating docker / remove docker / adding docker images in the same nanosecond. Would be open to feedback, but as of now, I will add a one second wait to the docker test to fix this issue.

What steps should a reviewer take to reproduce or test the bug or new feature?

Look above

Automated Testing & Documentation

Other information