Container Sentry

Container Sentry is a Firefox extension to open any URL (not just those with a specific domain) in a multi-account container. It also allows to specify regular expressions for urls which are allowed to be loaded outside a container.

This was needed because the VPN provider used by my employer opens a local html page which redirects to the authentication page. The Always in Container extension intercepts this request and breaks the context which in the end fails the logon to VPN.

The extension consists of a settings page (src/settings/) built with Vue.js, and a background script (src/background/). The settings page allows users to define regex patterns that, when matched against a URL loaded in the browser, will open that URL in a specified container tab. The background script listens for update events in browser tabs and performs the regex matching and opening of container tabs.

Firefox's Multi-Account Containers extension provides similar functionality out of the box, but only allows for matching URLs based on a domain. This extension allows for regex matching against the whole URL as opposed to exact matches based on domain.

How to use

Any url patterns which are to be used with this extension should not have their hostnames assigned to the MAC addon.

Exceptions

Use the settings page to define url pattern exceptions for which the extension should not try to contain them. However if the MAC addon has the host configured to open in a container it may still try to open it in the assigned container.

Pattern Container Mappings

Use the settings page to define url pattern to container mappings. It is possible that some of the intermediate pages may have to either added to the exceptions list. For example, for opening a corporate github repo in a work container, the github login page may redirect to the corporate login page. In this case, the itermediate github.com/enterprises page has to be added to the exceptions list.

Here is the configuration which worked for me:

• Exceptions
• .+github.com/enterprises+
• .+corporate_login_page_url.+ # This was needed for the VPN to work anyway.
• Pattern Container Mappings
• .+github.com.+corporate_github_org.+ -> Work
• .+github.com.+ -> Code