Docker-selenium nodes do not connect to hub - no route to host

Question

I recently migrated our grid RHEL7 server to RHEL8 server. While running run docker-compose on machine, the nodes do not connect to the hub.

docker-compose.yml

version: "3"

services:

  selenium-hub:

    image: selenium/hub:3.141.59-20200525

    container_name: selenium-hub

    ports:

      - "4444:4444"

  chrome:

    depends_on:

      - selenium-hub

    environment:

      - HUB_HOST=selenium-hub

      - HUB_PORT=4444

    image: selenium/node-chrome-debug:3.141.59-20200525

    volumes:

      - "/dev/shm:/dev/shm"

  firefox:

    depends_on:

      - selenium-hub

    environment:

      - HUB_HOST=selenium-hub

      - HUB_PORT=4444

    image: selenium/node-firefox-debug:3.141.59-20200525

    volumes:

      - "/dev/shm:/dev/shm"

  

test command:

$ docker-compose up --scale chrome=1 --scale firefox=0

terminal out:

selenium-hub    | 18:25:12.271 INFO [Hub.start] - Selenium Grid hub is up and running

selenium-hub    | 18:25:12.272 INFO [Hub.start] - Nodes should register to http://172.18.0.2:4444/grid/register/

selenium-hub    | 18:25:12.272 INFO [Hub.start] - Clients should connect to http://172.18.0.2:4444/wd/hub

chrome_1        | 2020-07-29 18:25:12,302 INFO success: fluxbox entered RUNNING state, process has stayed up for > than 0 seconds (startsecs)

chrome_1        | 18:25:12.472 INFO [GridLauncherV3.parse] - Selenium server version: 3.141.59, revision: e82be7d358

chrome_1        | 18:25:12.564 INFO [GridLauncherV3.lambda$buildLaunchers$7] - Launching a Selenium Grid node on port 5555

chrome_1        | 2020-07-29 18:25:12.632:INFO::main: Logging initialized @345ms to org.seleniumhq.jetty9.util.log.StdErrLog

chrome_1        | 18:25:12.789 INFO [WebDriverServlet.<init>] - Initialising WebDriverServlet

chrome_1        | 18:25:12.850 INFO [SeleniumServer.boot] - Selenium Server is up and running on port 5555

chrome_1        | 18:25:12.850 INFO [GridLauncherV3.lambda$buildLaunchers$7] - Selenium Grid node is up and ready to register to the hub

chrome_1        | 18:25:12.895 INFO [SelfRegisteringRemote$1.run] - Starting auto registration thread. Will try to register every 5000 ms.

chrome_1        | 18:25:14.130 WARN [SelfRegisteringRemote.registerToHub] - Error getting the parameters from the hub. The node may end up with wrong timeouts.No route to host (Host unreachable)

chrome_1        | 18:25:14.130 INFO [SelfRegisteringRemote.registerToHub] - Registering the node to the hub: http://selenium-hub:4444/grid/register

chrome_1        | 18:25:15.153 INFO [SelfRegisteringRemote$1.run] - Couldn't register this node: Error sending the registration request: No route to host (Host unreachable)

chrome_1        | 18:25:21.169 INFO [SelfRegisteringRemote$1.run] - Couldn't register this node: The hub is down or not responding: No route to host (Host unreachable)

Answer 1

Follow these steps:

  Install IpTables

$ yum install iptables-services

$ systemctl start iptables

$ systemctl enable iptables

Then, configure IpTables to allow the hub's port

$ sudo iptables -A INPUT -p tcp --dport 4444 -j ACCEPT

Now,shut down the firewall daemon

$ systemctl stop firewalld

Start or restart the docker daemon

$ systemctl restart docker

Want to learn Selenium, checkout our Selenium training.