Exercise : 3 Local Selenium Grid Hub and Node Using Docker Compose - Raneesh02/ref_workshop_2 GitHub Wiki

This document explains the Docker Compose configuration for setting up Selenium with Chrome. The provided Docker Compose file defines services for Selenium Grid with Chrome as the browser for running tests.

Step 1 : Create a Docker Compose File with name : docker-compose-v3.yml

version: "3"
services:
  chrome:
    image: selenium/node-chrome:latest
    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"

Note : For Mac, change chrome Image to seleniarm/node-chromium:latest and hub image to seleniarm/hub

Configuration Breakdown

  • version: "3" -> Specifies the version of the Docker Compose file format. Version 3 is compatible with Docker Compose 1.13.0 and later.

  • services -> Defines the services that make up your application. In this file, there are two services: chrome and selenium-hub.

  • chrome image: selenium/node-chrome:latest -> Uses the selenium/node-chrome Docker image with the latest tag to run the Chrome browser within the Selenium Grid. This image includes a pre-configured Chrome node for Selenium.

  • shm_size: 2gb: Sets the shared memory size to 2 GB. This is crucial for browser performance, particularly for running tests with Chrome, as it needs more shared memory for proper functioning.

  • depends_on: selenium-hub -> Specifies that the chrome service depends on the selenium-hub service. Docker Compose will start selenium-hub before starting chrome.

  • environment:

    • SE_EVENT_BUS_HOST=selenium-hub: Configures the Chrome node to communicate with the Selenium Hub. The SE_EVENT_BUS_HOST environment variable specifies the host of the Selenium Hub.
    • SE_EVENT_BUS_PUBLISH_PORT=4442: Sets the port for publishing events to the Selenium Hub.
    • SE_EVENT_BUS_SUBSCRIBE_PORT=4443: Sets the port for subscribing to events from the Selenium Hub. selenium-hub
    • image: selenium/hub:4.7.2-20221219: Uses the selenium/hub Docker image with the specified version. This image runs the Selenium Hub, which acts as the central point for distributing tests to different browser nodes.
  • container_name: selenium-hub: Assigns the container a custom name (selenium-hub) for easier identification.
  • ports:
    • "4442:4442": Maps port 4442 on the host to port 4442 on the container for the event bus publish port.
    • "4443:4443": Maps port 4443 on the host to port 4443 on the container for the event bus subscribe port.
    • "4444:4444": Maps port 4444 on the host to port 4444 on the container for the Selenium Grid console and communication with nodes.

Syntax of a docker compose yml : https://docs.docker.com/reference/compose-file/services/

Step 2 : Run all the services using command line

Copy above code and create a new filer docker in the root and cd into it

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

Step 3 : Scaling the Chrome Service

To scale the number of Chrome nodes, you can use the docker-compose up command with the scale option. This allows you to specify the number of instances you want to run. For example, to run 3 instances of the Chrome node, you would use:

docker compose -f docker-compose-v3.yml scale chrome=3

Also you could do it while starting the grid for first time

docker compose -f docker-compose-v3.yml up --scale chrome=3 -d

This command starts the number of specified Chrome nodes and connects them to the Selenium Hub, allowing for parallel test execution.

Step 4: Change girl URL value to localhost

Go to src/main/resources/configuration.properties and write localhost for gridurl value

selenium.gridurl=localhost

Step 5: Do the execution

Do the execution via command mvn test

Step 6: Tear Down

Make sure after all the testing you execute this command to tear down the containers

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

Note : Double check in docker desktop . No containers should be running , otherwise they will continue to consume system resources