Part 3 - Set up Selenium Grid with Docker compose

#automated #testing #selenium #grid #docker #framework #tool

#selenium_grid_with_docker_series #part3

As listed in main post and continue to Part 2, we will focus on setting up Selenium Grid using Docker compose in this Part 3 post.

Introduction

Docker Compose is a tool that was developed to help define and share multi-container applications. With Compose, we can create a YAML file to define the services and with a single command, can spin everything up or tear it all down.

So with Docker Compose, we can start Hub and all Nodes in one time run, instead of typing long command for each container start-up. It will ultimately save up a lot of time configuring those containers from scratch.

docker-compose-v3.yml

version: "3"
services:
  chrome:
    image: selenium/node-chrome:4.7.2-20221219
    shm_size: 2gb
    depends_on:
      - selenium-hub
    environment:
      - SE_EVENT_BUS_HOST=selenium-hub
      - SE_EVENT_BUS_PUBLISH_PORT=4442
      - SE_EVENT_BUS_SUBSCRIBE_PORT=4443

  firefox:
    image: selenium/node-firefox:4.7.2-20221219
    shm_size: 2gb
    depends_on:
      - selenium-hub
    environment:
      - SE_EVENT_BUS_HOST=selenium-hub
      - SE_EVENT_BUS_PUBLISH_PORT=4442
      - SE_EVENT_BUS_SUBSCRIBE_PORT=4443
      
  edge:
    image: selenium/node-edge:4.7.2-20221219
    shm_size: 2gb
    depends_on:
      - selenium-hub
    environment:
      - SE_EVENT_BUS_HOST=selenium-hub
      - SE_EVENT_BUS_PUBLISH_PORT=4442
      - SE_EVENT_BUS_SUBSCRIBE_PORT=4443

  selenium-hub:
    image: selenium/hub:4.7.2-20221219
    container_name: selenium-hub
    ports:
      - "4442:4442"
      - "4443:4443"
      - "4444:4444"

• version 3: It is the latest version of the docker-compose files.

• services(containers): This contains the list of the images and their configurations.

• image: It defines which image will be used to spin up container.

• shm_size: Use the host's shared memory.

• ports: Published ports in exposed port : container port format.

• container_name: Name of our containers.

• depends_on: This defines the required dependency before spinning up the container. In our docker-compose.yml file, containers Chrome and Firefox are dependent upon container hub to spin up.

• SE_EVENT_BUS_HOST: Hub host.

• SE_EVENT_BUS_PUBLISH_PORT and SE_EVENT_BUS_SUBCRIBE_PORT: Ports 4442 and 4443 are exposed by default for Event Bus ports to help them communicate with Hub.

Optional:

• SE_NODE_MAX_INSTANCES: This defines how many instances of same version of browser can run over the Remote System.

We can add more instance of Chrome to 4 instances by

docker compose -f docker-compose-v3.yml up --scale chrome=4

• SE_NODE_MAX_SESSIONS: This defines maximum number of concurrent sessions that will be allowed.

Run the docker compose file

• To execute this docker-compose yml file use

docker-compose -f docker-compose-v3.yml up

• Add the -d flag at the end for detached execution

docker-compose -f docker-compose-v3.yml up -d

• To stop the execution, hit Ctrl+C, and then

docker-compose -f docker-compose-v3.yml down

Execute compose file

And here is how they are in Docker Desktop (1 container for hub and 3 containers for 3 nodes)

And here is main page with 3 registered nodes

We can modify above yml to use noVNC by assign the default noVNC port of each node container (7900) to any port.

For example:

chrome:
    image: selenium/node-chrome:4.7.2-20221219
    shm_size: 2gb
    depends_on:
      - selenium-hub
    environment:
      - SE_EVENT_BUS_HOST=selenium-hub
      - SE_EVENT_BUS_PUBLISH_PORT=4442
      - SE_EVENT_BUS_SUBSCRIBE_PORT=4443
    ports:
      - "7901:7900"

Then we can inspect what runs inside browser of container by" http://localhost:7901/?autoconnect=1&resize=scale&password=secret

Or we can see that easily by clicking on video icon under Sessions tab.

Go to "View test run visually on browser" in Part 2 for more details.

Point test to exposed hub port

Point RemoteWebDriver in your test to http://localhost:4444

driver = new RemoteWebDriver(new URL("http://localhost:4444"),chromeOptions);

There is an example that I have already written in this repo: https://github.com/trongtuyen96/selenium-grid-docker-zalenium

Head to /test/java/DockerComposeTest.java for more details. To execute the test properly, you need to run the DockerCompose.xml file.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="DockerComposeTest_Suite">
    <test name="ChromeTest">
        <parameter name="browser" value="chrome"/>
        <classes>
            <class name="DockerComposeTest"/>
        </classes>
    </test>
    <test name="FirefoxTest">
        <parameter name="browser" value="firefox"/>
        <classes>
            <class name="DockerComposeTest"/>
        </classes>
    </test>
    <test name="EdgeTest">
        <parameter name="browser" value="edge"/>
        <classes>
            <class name="DockerComposeTest"/>
        </classes>
    </test>
</suite>

So the Chrome container will run test on Chrome browser, Firefox container will run test on Firefox and Edge container will run test on Edge.

Video recording for test execution

Tests execution can be recorded by using the selenium/video:ffmpeg-4.3.1-20221219 Docker image.

One container is needed per each container where a browser is running. This means if you are running 5 Nodes/Standalone containers, you will need 5 video containers, the mapping is 1-1.

Currently, the only way to do this mapping is manually (either starting the containers manually, or through docker-compose)

After the containers are stopped and removed, you should see a video file on your machine's /tmp/videos directory.

Please head to docker-compose-v3-video.yml for full details.

Summary

So it comes to an end now but we had a great series https://www.automatedtestingwithtuyen.com/post/selenium-grid-with-docker-series

here to learn and review.

I hope this series gives you a better understanding of Selenium Grid 4 in different modes with Docker and practically you can also set up the Grid and use it in your test automation.

Check out my repo: https://github.com/trongtuyen96/selenium-grid-docker-zalenium for more details.

Please drop your comments below if you have any queries, I will answer them as best as I can 😁.

Happy testing !!!