uap-vcl

Description

uap-vcl is a VCL module which parses a User-Agent string. It returns the user agent family, major version, minor version and patch version.

Why do this in VCL? This module follows the same rules as ua-parser, an open-source and community-driven, regexp-based user-agent parser. It has been ported to many different programming languages all of which share the same parser.

If you are already using a ua-parser-based parser on your origin then this module provides an easy migration path to moving User-Agent-based logic to VCL.

You can view the output for your current browser as HTML at: https://uap-vcl.freetls.fastly.net/

Or as JSON using:

$ curl https://uap-vcl.freetls.fastly.net/ -Haccept:application/json
{
  "ua_family": "curl",
  "ua_major": "7",
  "ua_minor": "50",
  "ua_patch": "3"
}

Installation

The module consists of a library, uap.vcl which you can include in your Fastly service.

This sets the following variables:

req.http.ua_family
req.http.ua_major
req.http.ua_minor
req.http.ua_patch

For example, it might return the following:

ua_family: "Chrome"
ua_major:  "67"
ua_minor:  "0"
ua_patch:  "3396"

Not all variables are set for every user agent. For example, Firefox might show:

ua_family: "Firefox"
ua_major:  "60"
ua_minor:  "0"
ua_patch:  "null"

Development

This works by parsing the ua-parser ruleset and generating VCL which follows its matching rules. It also includes a full test suite from ua-parser.

You should have access to the Fastly GitHub organization. Then run:

$ git clone git@github.com:fastly/uap-vcl.git
Cloning into 'uap-vcl'...
$ npm install
$ npm run generate

This generates uap.vcl.

Contributing

Send a pull request, but don't forget to:

$ npm run eslint
$ npm run prettier
$ npm run generate
$ npm run test

License

This code is available as open source under the terms of the Apache 2 License.

Copyright

Copyright 2018 Fastly, Inc.

Future

Is this useful? Let me know! Léon Brocard <leon@fastly.com>