Important: This documentation is about an older version. It's relevant only to the release noted, many of the features and functions have been updated or replaced. Please view the current version.

Using k6 browser

Browser options

Open source

Browser options

To enable browser testing, add the browser configuration within the options property of the Scenario options.

export const options = {
  scenarios: {
    foo: {
      executor: 'shared-iterations',
      options: {
        browser: {
          type: 'chromium',
        },
      },
    },
  },
};

Script options

Option	Description
type^(required)	Name of the browser running the test. Options include `'chromium'`.

Environment variable options

You can customize the behavior of the browser module by passing environment variables.

Note
Customizing browser options via environment variables is unsupported when running browser tests in Grafana Cloud k6.

Environment Variable	Description
K6_BROWSER_ARGS	Extra command line arguments to include when launching browser process. See this link for a list of Chromium arguments. Note that arguments should not start with `--` (see the command example below).
K6_BROWSER_DEBUG	All CDP messages and internal fine grained logs will be logged if set to `true`.
K6_BROWSER_EXECUTABLE_PATH	Override search for browser executable in favor of specified absolute path.
K6_BROWSER_HEADLESS	Show browser GUI or not. `true` by default.
K6_BROWSER_IGNORE_DEFAULT_ARGS	Ignore any of the default arguments included when launching a browser process.
K6_BROWSER_TIMEOUT	Default timeout for initializing the connection to the browser instance. `'30s'` if not set.
K6_BROWSER_TRACES_METADATA	Sets additional key-value metadata that is included as attributes in every span generated from browser module traces. Example: `K6_BROWSER_TRACES_METADATA=attr1=val1,attr2=val2`. This only applies if traces generation is enabled, refer to Traces output for more details.

The following command passes the browser options as environment variables to launch a headful browser with custom arguments.

$ K6_BROWSER_HEADLESS=false K6_BROWSER_ARGS='show-property-changed-rects' k6 run script.js

# WARNING!
# The grafana/k6:master-with-browser image launches a Chrome browser by setting the
# 'no-sandbox' argument. Only use it with trustworthy websites.
#
# As an alternative, you can use a Docker SECCOMP profile instead, and overwrite the
# Chrome arguments to not use 'no-sandbox' such as:
# docker container run --rm -i -e K6_BROWSER_ARGS='' --security-opt seccomp=$(pwd)/chrome.json grafana/k6:master-with-browser run - <script.js
#
# You can find an example of a hardened SECCOMP profile in:
# https://raw.githubusercontent.com/jfrazelle/dotfiles/master/etc/docker/seccomp/chrome.json.
docker run --rm -i -e K6_BROWSER_HEADLESS=false -e K6_BROWSER_ARGS='show-property-changed-rects' grafana/k6:master-with-browser run - <script.js

C:\k6> set "K6_BROWSER_HEADLESS=false" && set "K6_BROWSER_ARGS='show-property-changed-rects' " && k6 run script.js

PS C:\k6> $env:K6_BROWSER_HEADLESS="false" ; $env:K6_BROWSER_ARGS='show-property-changed-rects' ; k6 run script.js

Default arguments

List of default arguments included when launching the browser process. You can pass one or more of the arguments to the K6_BROWSER_IGNORE_DEFAULT_ARGS environment variable when starting a test for the ones you want to ignore.

Note
The starting ‘–’ have been omitted from the argument names in these lists.

Argument	Value	Description
disable-background-networking	`true`	Disables several subsystems which run network requests in the background. This is used during network performance testing to avoid measurement noise.
enable-features	NetworkService, NetworkServiceInProcess	Comma-separated list of feature names to enable.
disable-background-timer-throttling	`true`	Disables task throttling of timer tasks from background pages.
disable-backgrounding-occluded-windows	`true`	Disables backgrounding renders for occluded windows. Done for tests to avoid nondeterministic behavior.
disable-breakpad	`true`	Disables the crash reporting.
disable-component-extensions -with-background-pages	`true`	Disables default component extensions with background pages. Useful for performance tests where these pages may interfere with results.
disable-default-apps	`true`	Disables the installation of default apps on the first run. This is used during automated testing.
disable-dev-shm-usage	`true`	The /dev/shm partition is too small in certain VM environments, causing Chrome to fail or crash. This flag provides a work-around for this issue (a temporary directory will always be used to create anonymous shared memory files).
disable-extensions	`true`	Disables extensions.
disable-features	ImprovedCookieControls, LazyFrameLoading, GlobalMediaControls, DestroyProfileOnBrowserClose, MediaRouter, AcceptCHFrame	Comma-separated list of feature names to disable.
disable-hang-monitor	`true`	Suppresses hang monitor dialogs in renderer processes. This may allow slow unload handlers on a page to prevent the tab from closing, but the Task Manager can be used to terminate the offending process in this case.
disable-ipc-flooding-protection	`true`	Disables the IPC flooding protection. It is activated by default. Some javascript functions can be used to flood the browser process with IPC. This protection limits the rate at which they can be used.
disable-popup-blocking	`true`	Disables pop-up blocking.
disable-prompt-on-repost	`true`	Usually, when the user attempts to navigate to a page that was the result of a post request, the browser prompts to make sure that’s the intention of the user. This switch may be used to disable that check during automated testing.
disable-renderer-backgrounding	`true`	Prevents renderer process backgrounding when set.
force-color-profile	`srgb`	Forces all monitors to be treated as though they have the specified color profile. Accepted values are “srgb” and “generic-rgb” (currently used by Mac layout tests) and “color-spin-gamma24” (used by layout tests).
metrics-recording-only	`true`	Enables the recording of metrics reports but disables reporting. This executes all the code that a normal client would use for reporting, except the report is dropped rather than sent to the server. This is useful for finding issues in the metrics code during UI and performance tests.
no-first-run	`true`	Skips the “First Run” tasks, whether or not it’s the first run, and the “What’s New” page. This does not drop the “First Run” sentinel and thus doesn’t prevent “First Run” from occurring the next time Chromium is launched without this flag. It also does not update the last “What’s New” milestone, so it does not prevent “What’s New” from occurring the next time Chromium is launched without this flag.
enable-automation	`true`	Enables indication that the browser is controlled by automation.
password-store	`basic`	Specifies which encryption storage backend to use. The possible values are kwallet, kwallet5, gnome, gnome-keyring, gnome-libsecret, and basic. Any other value will lead to Chromium detecting the best backend automatically.
use-mock-keychain	`true`	Uses mock keychain on Mac to prevent the blocking permissions dialog about: “Chrome wants to use your confidential information stored in your keychain.”
no-service-autorun	`true`	Disables the service process from adding itself as an autorun process. This does not delete existing autorun registrations, it just prevents the service from registering a new one.
no-startup-window	`true`	Does not automatically open a browser window on startup (used when launching Chrome for the purpose of hosting background apps).
no-default-browser-check	`true`	Disables the default browser check. Useful for UI/browser tests where we want to avoid having the default browser info-bar displayed.
headless	`true`/`false`	Run in headless mode, i.e., without a UI or display server dependencies. Set by `K6_BROWSER_HEADLESS` environment variable (default true).
window-size	`800,600`	Sets the initial window size. Provided as string in the format “800,600”.

Additionally, the following arguments are set in headless mode (when K6_BROWSER_HEADLESS is true, which is the default option):

Argument	Value	Description
hide-scrollbars	`true`	Prevents creating scrollbars for web content. Useful for taking consistent screenshots.
mute-audio	`true`	Mutes audio sent to the audio device so it is not audible during automated testing.
blink-settings	primaryHoverType=2,availableHoverTypes=2, primaryPointerType=4,availablePointerTypes=4	Sets blink settings. Format is <name>[=<value>],<name>[=<value>],… The names are declared in settings.json5 from chromium project. For boolean type, use “true”, “false”, or omit ‘=<value>’ part to set to true. For enum type, use the int value of the enum value.