what is selenium grid
November 11, 2019

How to Use Selenium Grid in the Selenium Cloud

Continuous Testing

Selenium has been the leading web framework for automation for years--and for good reason. Selenium enables developers to automate web browser testing and releases frequently in order to offer the most up-to-date capabilities for its users. 

The new Selenium Grid makes it easier than ever to run tests in parallel on multiple devices or browsers, offering significant relief for heavy test loads, among numerous other benefits.

If your team is using Selenium, you need to know how to set up Selenium Grid in the cloud. 

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What Is Selenium Grid?

Selenium Grid is part of the Selenium testing suite. It enables parallel testing on different machines against different operating systems and browsers. This type of testing is referred to as distributed test execution.

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What Is the Purpose of Selenium Grid?

Selenium Grid offers significant relief for heavy test loads. Software development lifecycle becomes more demanding and complex. Finding ways to manage large test suites and long-running test suites is essential. 

The Grid works well with Agile software development. It allows test results to be delivered much faster, giving valuable feedback to development teams for the next cycle.

Selenium Grid Runs in Parallel

Selenium Grid runs in parallel:

  • Allows for a distributed test execution environment.
  • Reduces the total time it takes for a test suite to achieve a complete pass.
  • Accelerates the time to test pass by enabling parallel testing. 

With the Grid, you can set up multiple machines, either virtual machines or physical machines, to run a suite of tests. Because of the multiple machines the test suite will complete in a fraction of the time.

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How to Set Up Selenium Grid

Selenium Grid is based on a hub and node structure. At a high level, a grid includes a single hub and one or more nodes. The hub receives the test information to be executed. This includes specifications about the platform and browser where the test should be run.

The hub is programmed to “know” the configuration details of its registered nodes. The hub can use this information to identify an available node with the appropriate platform-browser combination.

When a node has been identified, Selenium commands are initiated by the hub to the specified node for the test. The node enacts the test in the browser against the application being tested.

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Why Use a Local Selenium Grid?

When choosing to implement a local Selenium Grid, there are certain considerations.

The biggest benefit is the amount of time it can save testing teams by allowing distributed parallel testing. The test automation framework is well-equipped to execute tests. More importantly, if tests fail, Selenium Grid provides diagnostic tools that shed light on the issue so it can be resolved.

Selenium Grid also supports focused testing, allowing particular tests to be assigned to specific computers. This leads to valuable flexibility in the test automation process.

There are also drawbacks.

Performance can be an issue, especially when there are many node servers. Another limitation is that the initial stages of Selenium Grid setup can be difficult. Especially for organizations that have not leveraged parallel testing before.

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How to Use a Selenium Test Environment

In more detail, let’s talk about the requirements to set up a Selenium test environment. The hub is the center of the Selenium Grid. It’s important to note that there can only be one hub. It is the master component of the entire architecture.

1. Download the Selenium Server Jar

Start by downloading the Selenium Server jar which can be found on the Selenium official website. Configure the hub (java -jar selenium-server-standalone-x.x.x.jar -role hub).

2. Configure the Hub

The hub uses port 4444 by default and can be modified using the configuration option.

Validation To validate your hub configuration, open a browser and navigate to

3. Set Up the Nodes

When your hub is confirmed, you then set up the nodes. Use the following command on the terminal:

java -jar selenium-server-standalone-3.9.1.jar -role node -hub http:///grid/register/ -browser "browserName=firefox,maxinstance=1,platform=WINDOWS" –port

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5 Advantages of Selenium Cloud

When teams consider a testing grid, there will be a choice required between building and maintaining on-premises testing or moving to the cloud.

In-house, on-premises infrastructure is managed and maintained by your IT team. The Selenium cloud testing setup is managed by a third-party vendor. A cloud-based testing platform enables functional testing of web apps completely free of physical infrastructure.

Choosing Selenium Grid in the cloud helps teams address challenges like scale, test reporting, version updates, stability, and cost. Let’s dive into these benefits.

1. Scalability

The software delivery landscape has changed dramatically in the last decade. Scalability is now essential as rapid growth is the norm in software development.

A cloud testing solution is made to scale. When an enterprise needs to expand, an enterprise cloud solution can flex as needed.

2. Reliability

In-house testing architecture inevitably falls prey to downtime. This could be because of network clogging. Or it could be other unforeseen issues. Either way, this can be a major issue when deadlines are tight.

Cloud servers have near-perfect availability so there is low risk of interruption.

3. Hardware Maintenance

On-prem solutions must be maintained. The maintenance includes configuring servers, maintaining desktops, and continually adding updated mobile devices. For organizations that don’t have sufficient resources for maintenance, a cloud solution is highly valuable.

SMBs may have it easy at the start, but once the team grows and testing needs become more complex, hardware becomes harder to maintain and scale.

4. Software Maintenance

Maintaining a testing stack is almost impossible today with the incredible number of browser and OS combinations being introduced every month. Without a cloud, infrastructure management and root cause analysis are required. These tasks can be resource intensive.

A cloud product has all this functionality built-in.

5. Consider True Cost of Ownership

To get to the root of the true cost of cloud vs. on-prem, start by considering the total cost of ownership (TCO). This involves reviewing the annual costs of building and maintaining an in-house testing architecture.

On-site factors in TCO include:

  • Annual salaries of your team resources.
  • Annual data center costs.
  • Cost per device used for testing activities.

Cloud factors include: 

  • Cost of mobile emulators and real devices.
  • Software licensing fees.

Both options are an investment. The key is to analyze which investment makes the most sense for your budget and resources.

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Use Selenium Grid With Perfecto

For fully optimized test automation, the infrastructure is crucial. Each framework has its benefits and limitations. When testing architecture is not chosen or implemented strategically, it can affect your product and bottom line.

Single server implementations are certainly a solid place to start. But in the long term, maintenance of a high-performance testing operation on-prem is expensive.

With a test cloud solution like Perfecto, you have powerful and flexible support in the cloud. Perfecto makes testing with Selenium cloud extremely effective with end-to-end continuous testing support.

Give it a try today.

Try Perfecto


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