Skip to content
WebSummoner

Capabilities

Capabilities are per-session settings passed with your Selenium new-session request. Any client that can send custom capabilities works; for clients that only allow W3C-standard capabilities, use the websummoner:options protocol extension (see below).

Quick reference

Section titled “Quick reference”
CapabilityTypeDefaultWhat it does
enableVNCbooleanfalseExpose the live browser screen over WebSocket
screenResolutionstring1920x1080x24Screen resolution, <width>x<height>x<depth>
enableVideobooleanfalseRecord the session to an H.264 video file
videoNamestring<session-id>.mp4Output video file name (keep the extension; plain file name only, no folders)
videoScreenSizestringscreen sizeVideo resolution, e.g. 1024x768 (trims from top-left)
videoFrameRateint12Video frames per second
videoCodecstringlibx264ffmpeg codec name (lower CPU alternatives exist)
enableAudiobooleantrueInclude the audio track in recordings (set false for video-only)

| enableLog | boolean | false | Save session log to a file | | logName | string | <session-id>.log | Log file name (keep the extension; plain file name only, no folders) | | name | string | — | Human-readable test name, shown in the UI | | sessionTimeout | duration | -timeout flag | Idle timeout, e.g. 30m or 10s; capped by -max-timeout | | timeZone | string | host time zone | IANA zone, e.g. Europe/Moscow | | env | array | — | Extra env vars for the browser container, ["K=V"] | | applicationContainers | array | — | Containers to link, ["name:alias"] | | hostsEntries | array | — | Extra /etc/hosts entries, ["host:ip"] | | dnsServers | array | Docker defaults | Custom DNS servers, ["192.168.0.1"] | | additionalNetworks | array | -container-network | Extra Docker networks to attach | | labels | map | — | Container labels, {"env": "testing"} | | containerHostname | string | container ID | Custom hostname inside the container | | s3KeyPattern | string | -s3-key-pattern | Override the S3 upload key pattern |

Session features

Section titled “Session features”

Live browser screen — enableVNC

Section titled “Live browser screen — enableVNC”
{ "enableVNC": true }

Works with images that ship a VNC server (the VNC column of Browser images). The screen is proxied to http://<host>:4444/vnc/<session-id> as a WebSocket — open it via WebSummoner UI for a point-and-click view.

Custom screen resolution — screenResolution

Section titled “Custom screen resolution — screenResolution”
{ "screenResolution": "1280x1024x24" }

This sets the screen resolution, not the browser window size. Browsers have a default window size, so screenshots can be smaller than the screen. Resize the window explicitly in your test. Because containers run headless browsers in Xvfb without a window manager, maximize does not work — use setSize instead.

Video recording — enableVideo and friends

Section titled “Video recording — enableVideo and friends”
{
  "enableVideo": true,
  "videoName": "my-cool-video.mp4",
  "videoScreenSize": "1024x768",
  "videoFrameRate": 24,
  "videoCodec": "mpeg4",
  "enableAudio": false
}

enableAudio is true by default — recordings capture the browser’s sound (see Recording audio). Set it to false explicitly when you want video-only recordings (privacy, CPU or file size reasons).

Requires a video recorder image — WebSummoner defaults to websummoner/video-recorder:latest-release, so recording works out of the box with the standard images. See the Video recording guide for retrieving and deleting files, codecs and disk planning.

Session logs — enableLog, logName

Section titled “Session logs — enableLog, logName”
{ "enableLog": true, "logName": "my-cool-log.log" }

To save logs for all sessions without asking per test, start WebSummoner with -save-all-logs. See Session logs for the retrieval API — and keep the log extension in logName.

Test name — name

Section titled “Test name — name”
{ "name": "myCoolTestName" }

Shown per session in the UI; makes debugging parallel runs much easier. Also added as a container label automatically.

Session environment

Section titled “Session environment”

Idle timeout — sessionTimeout

Section titled “Idle timeout — sessionTimeout”
{ "sessionTimeout": "30m" }

Go duration format (30m, 10s, 1h5m); values above the -max-timeout flag are clamped to it.

Time zone — timeZone

Section titled “Time zone — timeZone”
{ "timeZone": "Europe/Moscow" }

Any IANA zone. Without it, containers inherit the WebSummoner host time zone.

Environment variables — env

Section titled “Environment variables — env”
{ "env": ["LANG=ru_RU.UTF-8", "LANGUAGE=ru:en", "LC_ALL=ru_RU.UTF-8"] }

Appended to the variables set in browsers.json — useful for locale tests.

Networking

Section titled “Networking”

Linked application containers — applicationContainers

Section titled “Linked application containers — applicationContainers”
{ "applicationContainers": ["spring-application-main:my-cool-app", "spring-application-gateway"] }

Lets tests use URLs like http://my-cool-app/ against app containers on the same host.

Hosts entries — hostsEntries

Section titled “Hosts entries — hostsEntries”
{ "hostsEntries": ["example.com:192.168.0.1", "test.com:192.168.0.2"] }

Inserted before the entries from browsers.json, so capability entries win on conflicts.

DNS servers — dnsServers

Section titled “DNS servers — dnsServers”
{ "dnsServers": ["192.168.0.1", "192.168.0.2"] }

Overrides the Docker daemon DNS defaults for this session’s container.

Additional networks — additionalNetworks

Section titled “Additional networks — additionalNetworks”
{ "additionalNetworks": ["my-custom-net-1", "my-custom-net-2"] }

Containers always join the -container-network network; add more when the tested application lives elsewhere.

Metadata

Section titled “Metadata”

Container labels — labels

Section titled “Container labels — labels”
{ "labels": { "environment": "testing", "build-number": "14353" } }

Useful in clusters to enrich centralized logs (environment, VCS revision, build number). Overrides same-named labels from browsers.json.

S3 key pattern — s3KeyPattern

Section titled “S3 key pattern — s3KeyPattern”
{ "s3KeyPattern": "$quota/$fileType$fileExtension" }

Overrides the -s3-key-pattern flag for this session. Supported placeholders are listed in Uploading files to S3.

Passing capabilities as protocol extensions

Section titled “Passing capabilities as protocol extensions”

Some Selenium clients only accept W3C-standard capabilities. For those, WebSummoner reads the WebDriver protocol-extensions block under the websummoner:options key. These two requests are equivalent:

{ "browserName": "firefox", "version": "155.0.0", "screenResolution": "1280x1024x24" }
{
  "browserName": "firefox",
  "version": "154.0",
  "websummoner:options": { "screenResolution": "1280x1024x24" }
}