Selenium Docker: Testing public sites

Use Case

As a developer I would like to run functional tests against my public site and use docker-selenium as my testing environment.

What is docker-selenium?

Selenium team maintains a repository of Selenium stand-alone servers bundled with either Chrome or Firefox browser and packaged inside a Docker container. More info can be found on their public git page here.

Test process flow explained

1. wdio-docker-service will start a Selenium Docker image of your choice (ex. selenium/standalone-chrome).
2. Once service is running (normally on port 4444), tests will run (inside a container).
3. Once tests are finished wdio will report back results.

How do I configure that?

Assuming you have already setup wdio.conf.js, all you need to do is add docker configuration.

Example:

//wdio.conf.js
exports.config = {
    host: 'localhost',
    path: '/wd/hub', // Required to work with wdio v6
    specs: [
        './test/*.js'
    ],

    capabilities: [{
        browserName: 'chrome'
    }],

    sync: true,
    logLevel: 'debug',

    baseUrl: 'http://webdriver.io',

    waitforTimeout: 10000,
    connectionRetryTimeout: 90000,
    connectionRetryCount: 3,

    framework: 'mocha',
    mochaOpts: {
        ui: 'bdd'
    },

    services: ['docker'],
    dockerLogs: './',
    dockerOptions: {
        image: 'selenium/standalone-chrome',
        healthCheck: 'http://localhost:4444',
        options: {
            p: ['4444:4444'],
            shmSize: '2g'
        }
    }
};

Important parts above are host, services, dockerOptions.

• host - points to a Selenium running inside a container.
• service - here we specify that we want to use docker service (this project).
• dockerOptions - is what makes whole thing work :)
  • image - selenium-docker image for Chrome (service will "pull" it from DockerHUB)
  • healthCheck - here we specify URL of a Selenium server running inside a Docker container.
  • options - these are used to configure how Docker image is going to run
    • p - docker command used to map internal port of the service (running inside a container) to an outside port (on localhost). So what that means is that internally Selenium runs on port 4444 and we want to map it to the same port when accessing outside of the container.
    • shmSize - this is a recommended setting for this particular image. It configures shared memory needed to run Chrome browser.