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4. Variables in VCL

These variables describe the HTTP request received by Fastly.

Device detection

Fastly exposes a number of VCL variables describing the client hardware and softwarebased on knownUser-Agent strings. The data is automatically updated on aregular basis.

The data in these variables is based on mapping client-providedUser-Agent headersto an open source dataset provided by Fastly. Fastly periodically updates the datasetto have the most recent data, but we cannot guarantee its accuracy.

Presence of data

It's possible for data to be not known for a particularUser-Agent. When notpresent, numerical variables are set to-1, booleans are setfalse, andstrings are set to the empty string.

It's possible to distinguish data being not known from data being explicitlysetfalse by making use of theclient.identified variable.client.identified is set when all features are identified, and so a falsevalue for a property can be seen to be meaningful.

To find out more about variables that provide device vendor, model, andmanufacturer details, contact your Fastly account manager or salesrepresentative, or contactsupport@fastly.com.

• client.bot.name —Client device bot name
• client.browser.name —Client device web browser name
• client.browser.version —Client device web browser version
• client.class.bot —Client device is non-human traffic
• client.class.browser —Client device is a web browser
• client.display.touchscreen —Whether the client device display is a touch screen
• client.identified —Client user agent identified for device detection
• client.os.name —Client device OS name
• client.os.version —Client device OS version
• client.platform.gameconsole —Client device is a games console
• client.platform.hwtype —Client device primary hardware type
• client.platform.mediaplayer —Client device is a media player
• client.platform.mobile —Client device is mobile
• client.platform.model —Model of the client device
• client.platform.smarttv —Client device is a smart TV
• client.platform.tablet —Client device is a tablet
• client.platform.vendor —Client device vendor organization
• fastly_info.h2.is_push —Whether the request is part of a HTTP/2 push request
• fastly_info.host_header —The host header sent by the client
• req.body —Request body
• req.body.base64 —Request body (Base64-encoded)
• req.body_bytes_read —Total HTTP body bytes read from the client during a request
• req.bytes_read —Total bytes read from the client during a request
• req.enable_range_on_pass —Apply range handling for responses on pass
• req.enable_segmented_caching —Assemble the response from individually cacheable block-aligned file segments
• req.hash_always_miss —Force a miss for cached objects
• req.hash_ignore_busy —Don't wait for an ongoing fetch
• req.header_bytes_read —Total HTTP header bytes read from the client during a request
• req.headers —Collection of HTTP headers for a request
• req.http.{NAME} —HTTP headers by name for the request
• req.is_background_fetch —Whether VCL is being evaluated for astale while revalidate request to a backend
• req.is_purge —Whether the current request is a purge request
• req.method —HTTP method for the request
• req.postbody —Alias ofreq.body
• req.proto —HTTP protocol and version of the request
• req.request —Alias ofreq.method
• req.url —HTTP URL for the request (URL-encoded)
• req.url.basename —File trailing name component ofreq.url (URL-encoded)
• req.url.dirname —Directory name component ofreq.url (URL-encoded)
• req.url.ext —File extension component ofreq.url (URL-encoded)
• req.url.path —Path component ofreq.url (URL-encoded)
• req.url.qs —Query string name component ofreq.url (URL-encoded)
• req.xid —Request ID
• time.elapsed —Time since the request started
• time.elapsed.msec —Time since the request started (milliseconds)
• time.elapsed.msec_frac —Fraction of the millisecond portion of the time since the request started
• time.elapsed.sec —Time since the request started (seconds)
• time.elapsed.usec —Time since the request started (microseconds since Epoch)
• time.elapsed.usec_frac —Fraction of the microsecond portion of the time since the request started
• time.end —Time the request ended
• time.end.msec —Time the request ended (milliseconds since Epoch)
• time.end.msec_frac —Fraction of the millisecond portion of the time the request ended
• time.end.sec —Time the request ended (seconds since Epoch)
• time.end.usec —Time the request ended (microseconds since Epoch)
• time.end.usec_frac —Fraction of the microsecond portion of the time the request ended
• time.start —Time the request started
• time.start.msec —Time the request started (milliseconds since Epoch)
• time.start.msec_frac —Fraction of the millisecond portion of the time the request started
• time.start.sec —Time the request started (seconds since Epoch)
• time.start.usec —Time the request started (microseconds since Epoch)
• time.start.usec_frac —Fraction of the microsecond portion of the time the request started