Make express app Path Aware

[hyst3ric41]

** PLEASE ONLY USE THIS ISSUE TRACKER TO SUBMIT ISSUES WITH THE DOCKER SWARM VISUALIZER **

• If you have a bug working with Docker itself, not related to these labs, please file the bug on the Docker repo *
• If you would like general support figuring out how to do something with Docker, please use the Docker Slack channel. If you're not on that channel, sign up for the Docker Community and you'll get an invite. *
• Or go to the Docker Forums *

Please provide the following information so we can assess the issue you're having

Description

Image dockersamples/visualizer not working using traefik image as reverse proxy. I've done Docker Swarm deployed properly. I put dockersamples/visualizer image running as expected but proxied by traefik under the my.domain.com/my-path/ and I'm only getting the index.tpl file and not the Javascript file that makes app funcion properly. File index.tpl calls the script directly (="app.js") rather use relative path syntax (="./app.js"). When I call that Javascript file using a relative path the behavior it's as expected, and config traefik to proxy to the root path (/) works as well.

Steps to reproduce the issue, if relevant:
1.
2.
3.

Describe the results you received:

Being able to watch in live my swarm nodes under a proxied path by traefik.

Describe the results you expected:

I just get the HTML index page, but not the other elements that make app functions properly.

Additional information you deem important (e.g. issue happens only occasionally):

Output of docker version:

Docker version 24.0.7, build afdd53b

Output of docker info:

Client: Docker Engine - Community
 Version:    24.0.7
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.11.2
    Path:     /usr/libexec/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.21.0
    Path:     /usr/libexec/docker/cli-plugins/docker-compose

Server:
 Containers: 3
  Running: 3
  Paused: 0
  Stopped: 0
 Images: 4
 Server Version: 24.0.7
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Using metacopy: false
  Native Overlay Diff: true
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: systemd
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: active
  NodeID: yhoz1r5afnieivhetnheh51kz
  Is Manager: true
  ClusterID: zfjfz9e19646kknrpxp265r9x
  Managers: 1
  Nodes: 3
  Default Address Pool: 10.0.0.0/8  
  SubnetSize: 24
  Data Path Port: 4789
  Orchestration:
   Task History Retention Limit: 5
  Raft:
   Snapshot Interval: 10000
   Number of Old Snapshots to Retain: 0
   Heartbeat Tick: 1
   Election Tick: 10
  Dispatcher:
   Heartbeat Period: 5 seconds
  CA Configuration:
   Expiry Duration: 3 months
   Force Rotate: 0
  Autolock Managers: false
  Root Rotation In Progress: false
  Node Address: 34.70.254.180
  Manager Addresses:
   34.70.254.180:2377
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: a1496014c916f9e62104b33d1bb5bd03b0858e59
 runc version: v1.1.11-0-g4bccb38
 init version: de40ad0
 Security Options:
  apparmor
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 5.10.0-27-cloud-amd64
 Operating System: Debian GNU/Linux 11 (bullseye)
 OSType: linux
 Architecture: x86_64
 CPUs: 2
 Total Memory: 975.6MiB
 Name: swarm-node-1
 ID: 4f0f76d6-72fb-4afe-8c8f-2a0dd65cad53
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Username: pssatechies
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false

Additional environment details (AWS, Docker for Mac, Docker for Windows, VirtualBox, physical, etc.):