Sometimes it would be great to have a web browser in a specific version. Installing that on your machine may not be possible, but that is exactly the problem we can use dev containers for. Let’s look how Selenium and Docker can help us to get more flexibility (and additional features).
This post is part of my journey to learn Python. You can find the other parts of this series here. You find the code for this post in my PythonFriday repository on GitHub.
Preparation
Make sure that you have a working installation of Docker. If you run Docker on Windows, make sure that you install Docker as administrator – otherwise it may not work correctly.
Selenium Grid and Docker
Selenium Grid is a solution to run multiple browsers in parallel. That allows us to shorten the test runs and get more flexibility on the browser versions. We can install everything on our machine, but it is much faster to use an image for Docker that is ready to use.
We can tell Docker to fetch the image and run it in the deamon mode with this command:
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docker run -d -p 4444:4444 -p 7900:7900 --shm-size="2g" selenium/standalone-firefox:4.6.0-20221104 |
This gives us an image with Firefox for Selenium 4.6 that we can access on port 4444 on our machine.
Use the remote driver
In our Python code, we need to use the remote driver and point it to our running Docker container:
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import time from selenium import webdriver from selenium.webdriver.common.by import By firefox_options = webdriver.FirefoxOptions() driver = webdriver.Remote( command_executor='http://localhost:4444', options=firefox_options ) |
The rest of our code looks as before:
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# time.sleep(15) driver.get("https://duckduckgo.com/?t=ha&va=j") search_box = driver.find_element( by=By.ID, value="search_form_input_homepage") search_box.send_keys("Selenium web") search_button = driver.find_element( by=By.ID, value="search_button_homepage") search_button.click() title = driver.title print(title) results_div = driver.find_element( by=By.CLASS_NAME, value="results") results = results_div.find_elements( by=By.TAG_NAME, value="h2") for result in results: print(f"* {result.text}") time.sleep(15) driver.quit() |
Run the code
We can run our code and it will connect to Selenium Grid, run a Firefox browser, and interact with the DuckDuckGo.com site. If everything works, we should get an output like this:
Selenium web at DuckDuckGo
* Selenium
* WebDriver | Selenium
* Selenium WebDriver Tutorial – javatpoint
* Selenium Webdriver Tutorial with Examples | BrowserStack
* Selenium (software) – Wikipedia
* Complete Selenium WebDriver Tutorial with Examples – LambdaTest
* How Selenium WebDriver Works – c-sharpcorner.com
* Introduction to Web Scraping using Selenium – Medium
* Web Scraping with Selenium and Python – ScrapFly Blog
* Selenium IDE · Open source record and playback test automation for the web
See the browser in action
If you add a delay of 15 seconds before the driver navigates to DuckDuckGo, you have enough time to watch the Browser in the Docker container:
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time.sleep(15) driver.get("https://duckduckgo.com/?t=ha&va=j") ... |
Go to http://localhost:4444/ui#/sessions to see your current session (if it is not there yet, refresh the page until it appears):
Click on the video icon, enter “secret” as the password and you can watch the browser while it gets automated by Selenium:
Next
We now have the first part of Selenium Grid in working order. Next week we explore how we can add multiple browsers and run our tests in parallel.
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