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Configure Local Testing with a PAC file
Use a Proxy Auto-Configuration (PAC) file to route BrowserStack Local traffic through your organization’s proxy, with example rules and supported PAC functions.
If your organization uses a PAC file to decide which requests go through a proxy, point BrowserStack Local at the same file. Local Testing then follows your organization’s proxy rules for every product, including Automate, App Automate, Live, and App Live.
Configure a proxy using a PAC file
A Proxy Auto-Configuration (PAC) file contains a JavaScript function, FindProxyForURL, that decides whether each request goes directly to its destination or through a proxy server. Point BrowserStack Local at your PAC file to apply the same rules to Local Testing traffic.
PAC files don’t support proxy authentication. If your proxy returns HTTP error 407, see Troubleshoot PAC file issues.
Sample PAC file
The following PAC file sends requests for plain hostnames, such as localhost, directly. All other requests go through the proxy:
If you aren’t sure what your PAC file does, or you aren’t allowed to change it, contact your network or IT team. For more examples and the list of supported PAC functions, see Example PAC file rules.
Add the PAC file to BrowserStack Local
The PAC file must be on the machine that runs BrowserStack Local. If your PAC file is hosted at a URL, download it and use the absolute path of the downloaded file.
Choose how you run BrowserStack Local and complete the steps:
Add the absolute path of your PAC file to your browserstack.yml file:
Example PAC file rules
BrowserStack Local evaluates the FindProxyForURL(url, host) function in your PAC file for each request. Write your rules using the host parameter, because rules based on the url parameter aren’t supported. Use the following examples as a starting point.
Route requests for one domain through a proxy, and send all other requests directly:
Route requests for two domains through different proxies, and send all other requests directly:
Route requests for private network addresses through a proxy, and send all other requests directly:
Supported PAC functions
BrowserStack Local supports the following functions in PAC files:
| Function | Supported | Notes |
|---|---|---|
dateRange |
Yes | N/A |
dnsDomainIs |
Yes | N/A |
dnsDomainLevels |
Yes | N/A |
dnsResolve |
Yes | N/A |
isInNet |
Yes | N/A |
isPlainHostName |
Yes | N/A |
isResolvable |
Yes | N/A |
localHostOrDomainIs |
Yes | N/A |
myIpAddress |
Yes | N/A |
shExpMatch |
Yes | N/A |
timeRange |
Yes | N/A |
weekdayRange |
Yes | N/A |
split |
Yes | Not part of the PAC specification. Implemented as String.prototype.split. |
alert |
No | N/A |
Limitations
The following features don’t work with PAC files:
| Not supported | Alternative |
|---|---|
Rules based on the url parameter of FindProxyForURL
|
Write rules based on the host parameter. |
| Proxy authentication, including implicit methods such as Kerberos and NTLM | Use a proxy that doesn’t require authentication, or contact your network or IT team for alternatives. |
Debug Utility (--debug-utility, --debug-url) |
Find the proxy that your PAC file returns, and test it directly with the --proxy-host and --proxy-port flags. |
Troubleshoot PAC file issues
BrowserStack Local returns Unable to parse the supplied PAC file
Make sure that your PAC file is valid JavaScript and isn’t minified. In a minified file, comments can merge with the code, which stops BrowserStack Local from parsing the file.
Debug Utility doesn't work with a PAC file
Debug Utility (--debug-utility, --debug-url) doesn’t work with the --pac-file flag. To test connectivity, find the proxy that your PAC file returns for the site, and run the Local binary with the --proxy-host and --proxy-port flags instead.
To find the proxy, run the Local binary with your PAC file and verbose logging, --verbose 3. The logs show the proxy used for each host, for example:
[Pac Resolver] Proxy to use for example.com is proxy.example.com:8080
If these log lines don’t appear, add the --force-local and --force-proxy flags so that all traffic goes through the proxy.
The proxy returns HTTP error 407
PAC files don’t support authentication. If you get HTTP error 407 with BrowserStack Local but not in your browser, your network might use implicit authentication, such as Kerberos, NTLM, or a custom method. BrowserStack Local doesn’t support authentication with PAC files, so contact your network or IT team for alternatives.
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