Selenium.WebDriverException: Message: unknown error: net::ERR_NAME_NOT_RESOLVED

Question

I am trying to user latest selenium hub in docker and try to run pytests in docker or without it for debug. I set up selenium according to official documentation. I used 3 version for docker compose: https://github.com/SeleniumHQ/docker-selenium/blob/trunk/docker-compose-v3.yml

Containers started fine:

Also health check is ok:

{
  "value": {
    "ready": true,
    "message": "Selenium Grid ready.",
    "nodes": [
      {
        "id": "9b050c95-76e1-4ed3-be7e-a320630fdf1e",
        "uri": "http:\u002f\u002f192.168.32.4:5555",
        "maxSessions": 8,
        "stereotypes": [
          {
            "capabilities": {
              "browserName": "chrome"
            },
            "count": 8
          }
        ],
        "sessions": [
        ]
      },
      {
        "id": "d4e6d3a1-140d-41c9-b9c6-38fd5b6677b5",
        "uri": "http:\u002f\u002f192.168.32.5:5555",
        "maxSessions": 8,
        "stereotypes": [
          {
            "capabilities": {
              "browserName": "firefox"
            },
            "count": 8
          }
        ],
        "sessions": [
        ]
      }
    ]
  }
}

I am trying to start tests via pycharm (not in docker) on localhost:4444 and receive next error:

self = <selenium.webdriver.remote.errorhandler.ErrorHandler object at 0x7fe353e9c0d0>
response = {'status': 500, 'value': '{"value":{"error":"unknown error","message":"unknown error: net::ERR_NAME_NOT_RESOLVED\\n  (Session info: chrome=85.0.4183.83)","stacktrace":"#0 0x56398a84caa9 \\u003Cunknown>\\n"}}'}

Browser version for chrome is 85.0.4183.83 I start browser in conftest.py:

browser = webdriver.Remote(
            command_executor=f"http://{os.environ['SE_EVENT_BUS_HOST']}:4444/wd/hub",
            desired_capabilities={
                'browserName': browser_name
            }
        )

I tried to set localhost there as well as selenium-hub. In docker compose I also added pytests section to try set up tests in docker:

  pytests:
    container_name: selenium_pytests
    #    network_mode: host
    command: /bin/sleep infinity
    build: .
    environment:
      - SE_EVENT_BUS_HOST=selenium-hub
    volumes:
      - ./reports:/opt/app/reports

While running pytests in docker I do not see hub. Trying to check by selenium-hub and localhost as well:

My wait-for-it.sh:

#!/bin/bash
# wait-for-grid.sh

set -e

cmd="$@"

while ! curl -sSL "http://selenium-hub:4444/wd/hub/status" 2>&1 \
        | jq -r '.value.ready' 2>&1 | grep "true" >/dev/null; do
    echo 'Waiting for the Grid'
    sleep 1
done

>&2 echo "Selenium Grid is up - executing tests"

Tried curl there: localhost, selenium-hub.

Previously I was using environment HUB_HOST=hub. That works for me for running tests in docker but I got same error ERR_NAME_NOT_RESOLVED for running tests out of docker.

Answer 1

Please try running docker selenium hub with mode:global also instead of using hub try with HUB_HOST=selenium-hub once.

Chart working for me

version: "3.6"
services:
  selenium-hub:
    restart: always
    image: selenium/hub:3.14.0
    container_name: selenium-hub
    ports:
      - "4444:4444"

 chrome:
    restart: always
    image: selenium/node-chrome-debug:3.14.0
    ports:
      - "5900-5999:5900"
    depends_on:
      - selenium-hub
    environment:
      HUB_HOST: selenium-hub
      HUB_PORT_4444_TCP_ADDR: selenium-hub
      HUB_PORT_4444_TCP_PORT: 4444
      DBUS_SESSION_BUS_ADDRESS: "/dev/null"
    links:
      - selenium-hub:hub