Parallel execution of tests using Selenoid and Python

Learn how to swiftly set up a Selenium test cluster using Docker and Selenoid. Selenoid is a powerful tool that launches browsers in isolated Docker containers, making it ideal for automating web application testing. It serves as a Selenium WebDriver protocol implementation and is the primary tool for real browser-based automated testing.

Follow the provided instructions to install and configure Docker, upload the Selenoid Configuration Manager, and run Python tests in parallel with ease. By following these steps, you can quickly set up a cluster for Selenium tests and streamline your web application testing process.

Selenoid source code and documentation: Selenoid


Selenoid Docker Python

To get started with running Python tests in parallel using Docker and Selenoid, follow these steps:

  1. Install Docker on macOS.
  2. Upload Selenoid, which is a Configuration Manager for Dockerized browsers.
  3. Start the web-UI and Hub components of Selenoid.
  4. Execute your Python tests in parallel using the configured Selenoid setup.

In order to install and configure Docker, please refer to the instructions provided HERE. In summary, the process involves creating a profile on Docker Hub, uploading and installing the Docker Desktop application, and logging in through the terminal.

By following these steps, you will be able to successfully install and configure Docker, allowing you to leverage its capabilities for your development and deployment needs.

After installing and setting up Docker, the next step is to upload the Configuration Manager utility. This utility is responsible for managing the configuration of your Docker environment.

To upload the Configuration Manager, follow these steps:

curl -s | bash

On Linux and Mac OS
./cm selenoid start --vnc

To override Selenoid listen port add --port flag:
./cm selenoid start --port 4445
Selenoid help / stop
./cm selenoid --help
./cm selenoid stop
$ ./cm selenoid stop
Using Docker
- Your Docker API version is 1.39
Stopping Selenoid...
Successfully stopped Selenoid
$ ./cm selenoid-ui stop
Using Docker
- Your Docker API version is 1.39
Stopping Selenoid UI...
Successfully stopped Selenoid UI
docker --version
docker image ls
docker ps -a
ipconfig getifaddr en0

ls – command list, return all Dockers tom
ps -a – show Docker containers that are currently running
ipconfig – command shows IP address on MacOs

“ls” – Lists files and directories. (Note: For Docker, use “docker ps” to list running containers or “docker images” to list available images.)

“ps -a” – Displays information about all processes, including Docker containers. Shows running and stopped containers.

“ipconfig” – Displays IP configuration on Windows. (For macOS, use “ifconfig” or “ip addr show” for network interface information.)

Selenoid Web version, default:

./cm selenoid-ui start

Test code example:

from selenium import webdriver
from selenium.webdriver.common.keys import Keys
capabilities = {
    "browserName": "chrome",
    "version": "90.0",
    "platform": "LINUX"
driver = webdriver.Remote(
print 'Session ID is: %s' % driver.session_id
print 'Opening the page...'
 assert "Python" in driver.title
 elem = driver.find_element_by_name("q")
 assert "No results found." not in driver.page_source
print 'Taking screenshot...'
driver.get_screenshot_as_file(driver.session_id + '.png')

To add or change browser versions, you need to edit the browsers.json configuration file (PATH: .aerokube / selenoid)

    "chrome": {
        "default": "91.0",
        "versions": {
            "90.0": {
                "image": "selenoid/chrome:90.0",
                "port": "4444",
                "path": "/"
            "91.0": {
                "image": "selenoid/chrome:91.0",
                "port": "4444",
                "path": "/"
    "firefox": {
        "default": "89.0",
        "versions": {
            "88.0": {
                "image": "selenoid/firefox:88.0",
                "port": "4444",
                "path": "/wd/hub"
            "89.0": {
                "image": "selenoid/firefox:89.0",
                "port": "4444",
                "path": "/wd/hub"
    "opera": {
        "default": "76.0",
        "versions": {
            "75.0": {
                "image": "selenoid/opera:75.0",
                "port": "4444",
                "path": "/"
            "76.0": {
                "image": "selenoid/opera:76.0",
                "port": "4444",
                "path": "/"
    "safari": {
        "default": "14.0",
        "versions": {
            "14.0": {
                "image": "browsers/safari:14.0",
                "port": "4444",
                "path": "/"

Also upload new browser image:

docker pull browsers/safari:13.0
docker pull browsers/safari:14.0
 % docker image ls                 
REPOSITORY                TAG              IMAGE ID       CREATED         SIZE
selenoid/firefox          89.0             aa32a7fb78d4   8 days ago      1.1GB
selenoid/chrome           91.0             8f9abf8b7783   2 weeks ago     1.09GB
selenoid/opera            76.0             0d581d76417b   5 weeks ago     1.06GB
selenoid/firefox          88.0             76d9488c8ee8   7 weeks ago     1.1GB
selenoid/chrome           90.0             0e14eff7be65   2 months ago    1.07GB
browsers/safari           14.0             4052e42b4cef   2 months ago    918MB
selenoid/opera            75.0             4a7ec014e6c0   2 months ago    1.06GB
aerokube/selenoid         1.10.3           cb9dc8b9ed2c   2 months ago    16.5MB
aerokube/selenoid-ui      1.10.3           8dfa15d6e0d4   3 months ago    17.5MB
browsers/edge             89.0             093b827792ac   5 months ago    972MB
browsers/edge             88.0             739f028bfc9c   6 months ago    1.62GB
browsers/safari           13.0             fec2bd5eda07   11 months ago   753MB
selenoid/video-recorder   latest-release   b7300761e77e   14 months ago   27.4MB

Congratulations on successfully setting up your Selenium test cluster with Docker and Selenoid! By leveraging Docker’s containerization and Selenoid’s browser launching capabilities, you can automate web application testing efficiently. The article covers the installation and configuration of Docker, uploading the Selenoid Configuration Manager, and executing Python tests in parallel. Enjoy the benefits of a streamlined testing workflow with Docker and Selenoid.

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