Manual:$wgShellboxUrls

Shell and process control: $wgShellboxUrls
Shell commands can be run on a remote server using Shellbox .
Introduced in version:1.37.0 (Gerrit change 700325; git #50888be5)
Removed in version:still in use
Allowed values:(array)
Default value:[ 'default' => null, ]

Details edit

Shell commands can be run on a remote server using Shellbox . To use this feature, set this to the URLs mapped by the service, and also configure $wgShellboxSecretKey . You can also disable a certain service by setting it to false or null.

'default' would be the default URL if no URL is defined for that service.

For more information about installing Shellbox, see Shellbox