Stephan Hochdörfer has shared a handy tip for the Composers users out there that may have to deal with username/password protected repositories as a part of your package install process. In his post he shows how to use a simple "expect" script to automatic the HTTP Basic Auth login.
A couple of months ago when we set-up our own internal Satis repository to host our custom Composer packages. We ran into an "unpleasant" issue with Composer that had this PR as an result. To sum things up: We are using HTTP Basic Auth to password-project our Satis repository. There was no way we could switch to an SSL client certificate to allow Composer to authenticate itself automatically without asking for a password. Asking for the password on a developer`s machine is no big thing, but it since we need an automated Composer run in our Jenkins environment, there was no way to set things up.
As Composer doesn't currently support this functionality, they had to find a way around it. They went with an expect script that is used to work with the prompts and send the username/password information when expected. He also points out that this could be useful for other situations and tools - like a Bower build.