Test automation: scalable Selenoid as an alternative for Selenium Grid

Since this article was published, Selenium Grid alternatives have significantly evolved. Read our updated comparison including Playwright and Cypress here.

Selenium Grid is a widely spread solution used by test automation engineers. It provides a distributed environment for parallel execution of multiple tests. However, QA engineers encounter bottlenecks when running large test suites or many parallel sessions on a Grid, which can be addressed in many cases using an open-source project named Selenoid.

This article will explore what Selenoid is, how it works as one of the practical approaches to scaling Selenium-based parallel testing, and how it can help you save time and streamline automated test performance, as well as provide a high-quality solution at short notice.

What is peculiar about Selenium Grid?

Traditional Selenium Grid is a cluster consisting of several Selenium servers. It allows users to create a distributed network for a simultaneous launch of tests in multiple browsers. It incorporates a central server (hub) and nodes connected to it that require careful setup and configuration.

Although the solution is in high demand, the following peculiarities are often encountered in classic Selenium Grid setups:

• Time-consuming deployment process

Engineers have to fulfill the following steps to deploy Selenium Grid:

• Complex launch commands

The commands to initiate server and node launch look as follows:

• Performance speed reduction

The hub decelerates if multiple browsers are run in different nodes.

• Compatibility issue

Browser and node versions should be compatible to avoid conflicts.

Is there a solution?

Some issues, such as a long deployment process, can be optimized by means of Docker. This software platform is developed for quick application build, debugging and deployment.

Engineers elaborate the image and after that proceed with the implementation of a container. It covers all aspects necessary for the application performance: libraries, system tools, code, and execution environment.

Even official Selenium images with multiple browser versions will not always fully eliminate browser launch bottlenecks since core Selenium Grid peculiarities remain constant.

Alternatively, teams may choose to rely on cloud-based testing services to eliminate the need for complex infrastructure setup and maintenance, especially when quick scalability and ready-to-use environments are required. However, for those who prefer to keep testing infrastructure under their control, there are other efficient solutions available.

Selenoid as an alternative to Selenium Grid

Quickly and easily customizable Selenoid can become a robust option. This tool helps to run browsers in Docker containers, offering an alternative to traditional Grid infrastructure as well as cloud-based services such as BrowserStack. The process is different, although.

Selenoid focuses on providing scalable browser infrastructure for Selenium-based automation. At the same time, many teams today also consider opting for more modern testing frameworks such as Playwright and Cypress. Unlike Selenium, they provide built-in parallelization and simplified test APIs and are often chosen when teams prefer lightweight automation solutions without having to manage infrastructure themselves.

Returning to Selenoid’s core functionality, the tool launches a new container for each new browser request and stops it after the session is closed.

A certain browser version, the required version of the web driver or Selenium-server, which supports this browser and all necessary dependencies (for instance, graphics libraries) form each container.

All browser processes are fully isolated. This allows launching an unhindered number of multiple browser versions concurrently.

Selenoid is written in the Go programming language and supports all popular browsers.

Do you want to make the life of your team easier? Consider test automation. It will come as a relief to both Dev and QA teams. 

Selenoid vs. Selenium Grid

Both solutions pursue one objective, which is the elaboration of a single environment for a parallel launch of automated tests. However, these solutions differ a lot.

Selenoid advanced features

Selenoid comprises a number of additional functions that contribute to workflow optimization.

• Data storage in RAM

Selenoid stores all temporary files in tmpfs.

Tmpfs is a temporary file repository that allows storing files in RAM, access to which is performed much faster than to the file system of the hard drive.

• Various screen resolution types

QA engineers can configure the appropriate screen resolution for a running container on their own by setting the required parameters in the Browser Capabilities.

• Browser screen display

Selenoid enables engineers to connect to the VNC port during tests execution and access the screen of the desired browser. It’s even possible to interfere in the process of running the automated test using the mouse.

• Video recording of tests

It’s possible to record the video of the tests performed.

For instance, the activation in the Google Chrome browser is implemented by setting the parameter true in the Browser Capabilities:

ChromeOptions options = new ChromeOptions ();

options.setCapability (“enableVideo”, true).

Summarizing

Due to multiple benefits, Selenoid is a robust solution for teams relying on Selenium-based automation and self-hosted infrastructure.

This scalable alternative helps to change configuration settings seamlessly according to the preferences and needs of your team, cut corners on resource consumption, and perform tests in due course.

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