Suppose you are to setup test automation. Building and maintaining a whole test infrastructure all by your team can be painful. Although some cloud services like Sauce Labs do cover DevOps, you may have hesitated to use them due to security issues or budget concerns in your company. Docker is a good tool for you to setup and maintain servers for test automation, especially if you are just starting to build an automation test infrastructure with open source solutions.
Of the open source solutions, Selenium is an open source framework for automating UI tests. It allows you to simulate user flow by executing scripts on different browsers. Selenium-Grid consists of hub servers and node servers to let you execute tests in parallel to speed up testing. When a hub receives requests from clients, the requests are rerouted to an appropriate node server, based on the capability parameters.