[🐛 Bug]: Disabling VNC does not quite work

[MJB222398]

What happened?

I have to use a poverty spec machine so need to conserve resources. I do not need VNC so I want to disable that to save memory etc. I set the following environment variables:

SE_START_VNC=false
SE_START_NO_VNC=false

This does seem to disable VNC in the sense that I can longer connect using my VNC client. However if I look at the Selenium Grid web UI at http://localhost:4444/ui/# this doesn't appear to reflect this properly.

Hovering over the '1' icon for my Chrome Node I can see the following:

{"browserName":"chrome","browserVersion":"127.0","goog:chromeOptions":{"binary":"/usr/bin/google-chrome"},"platformName":"linux","se:containerName":"","se:noVncPort":7900,"se:vncEnabled":true}

Why is it saying "se:vncEnabled":true? And also why is it saying "se:noVncPort":7900 for that matter?

Furthermore if I go to the sessions page (http://localhost:4444/ui/#/sessions) then I can see a camera/video icon next to my session to launch the VNC viewer. If I click this it doesn't work but I would expect that this icon/button should not be there at all.

Have I managed to disable VNC or not? Am I saving resources or not? Do I need to set START_VNC and START__NO_VNC too? Its just unclear and doesn't fill me with confidence that it is doing what I want it to.

As well as the variables above do I also need to set SE_START_XVFB=false? If I do then I get catastrophic issues so assume not.

Command used to start Selenium Grid with Docker (or Kubernetes)

# To execute this docker-compose yml file use `docker-compose -f docker-compose.yml up`
# Add the `-d` flag at the end for detached execution
# To stop the execution, hit Ctrl+C, and then `docker-compose -f docker-compose.yml down`
version: "3"
services:
  chrome:
    image: selenium/node-chrome:4.23.0-20240727
    container_name: chrome-node
    shm_size: 2gb
    privileged: true
    depends_on:
      - selenium-hub
    environment:
      - HUB_HOST=selenium-hub
      - SE_EVENT_BUS_HOST=selenium-hub
      - SE_START_VNC=false
      - SE_START_NO_VNC=false
      - SE_EVENT_BUS_PUBLISH_PORT=4442
      - SE_EVENT_BUS_SUBSCRIBE_PORT=4443
      - SE_NODE_MAX_SESSIONS=1
      - SE_NODE_GRID_URL=http://localhost:4444
      - SE_NODE_SESSION_TIMEOUT=180
    ports:
      - "6900:5900"
    networks:
      - selenium_grid_internal

  chrome_video:
    image: selenium/video:ffmpeg-7.0.1-20240727
    container_name: chrome-video
    privileged: true
    volumes:
      - ${VIDEOS_DIRECTORY:-./videos}:/videos
    depends_on:
      - chrome
    environment:
      - DISPLAY_CONTAINER_NAME=chrome
      - FILE_NAME=chrome_video.mp4
    networks:
      - selenium_grid_internal

  selenium-hub:
    image: selenium/hub:4.23.0-20240727
    privileged: true
    container_name: selenium-hub
    hostname: selenium-hub
    ports:
      - "4442:4442"
      - "4443:4443"
      - "4444:4444"
    environment:
      - GRID_TIMEOUT=120000
      - GRID_BROWSER_TIMEOUT=120000
    networks:
      - selenium_grid_internal

networks:
  selenium_grid_internal:

Relevant log output

2024-12-10 19:14:29,438 INFO spawned: 'vnc' with pid 1412
2024-12-10 19:14:29,439 INFO spawned: 'novnc' with pid 1413
2024-12-10 19:14:29,441 WARN exited: vnc (exit status 0; not expected)
2024-12-10 19:14:29,442 WARN exited: novnc (exit status 0; not expected)
2024-12-10 19:14:32,446 INFO spawned: 'vnc' with pid 1425
2024-12-10 19:14:32,447 INFO spawned: 'novnc' with pid 1426
2024-12-10 19:14:32,449 WARN exited: vnc (exit status 0; not expected)
2024-12-10 19:14:32,449 INFO gave up: vnc entered FATAL state, too many start retries too quickly
2024-12-10 19:14:32,450 WARN exited: novnc (exit status 0; not expected)
2024-12-10 19:14:33,451 INFO gave up: novnc entered FATAL state, too many start retries too quickly

Operating System

Ubuntu 20.04

Docker Selenium version (image tag)

4.23.0-20240727

Selenium Grid chart version (chart version)

No response

[github-actions]

@MJB222398, thank you for creating this issue. We will troubleshoot it as soon as we can.

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Thank you!

[VietND96]

Try to use Node version 4.26.0+, I think it will be fixed by SeleniumHQ/selenium#14584

[MJB222398]

@VietND96 Thanks, unfortunately I cannot update right now due to other bugs/deprecations/limitations so I will take your word for it. Looking at your PR though I see it only deals with the SE_ prefixed versions of the variables. My understanding from reading other code was that these SE_ prefixed ones are only used as fallbacks if the unprefixed ones are not set. So I suppose my questions is, if I were to upgrade to 4.26+ could you be explicit about which variables (out of START_VNC, START_NO_VNC, START_XVFB, SE_START_VNC, SE_START_NO_VNC, SE_START_XVFB) I need to set to disable any and all VNC servers for my peace of mind?

[VietND96]

It's AND logic, so just one env var is false e.g SE_START_VNC=false, the recorder icon should be disabled (in the container, VNC will not start, and noVNC as well).
List env vars can be configured - https://www.selenium.dev/documentation/grid/configuration/cli_options/#node
Via SE_OPTS, set --vnc-env-var START_XVFB START_VNC START_NO_VNC.

[MJB222398]

@VietND96 Ok thanks, I just noticed also in the logs that I get this:

2024-12-10 19:14:29,438 INFO spawned: 'vnc' with pid 1412
2024-12-10 19:14:29,439 INFO spawned: 'novnc' with pid 1413
2024-12-10 19:14:29,441 WARN exited: vnc (exit status 0; not expected)
2024-12-10 19:14:29,442 WARN exited: novnc (exit status 0; not expected)
2024-12-10 19:14:32,446 INFO spawned: 'vnc' with pid 1425
2024-12-10 19:14:32,447 INFO spawned: 'novnc' with pid 1426
2024-12-10 19:14:32,449 WARN exited: vnc (exit status 0; not expected)
2024-12-10 19:14:32,449 INFO gave up: vnc entered FATAL state, too many start retries too quickly
2024-12-10 19:14:32,450 WARN exited: novnc (exit status 0; not expected)
2024-12-10 19:14:33,451 INFO gave up: novnc entered FATAL state, too many start retries too quickly

Doesn't seem right?

[VietND96]

Let me check it. It should not spawn pid again with a confused message.