Support Upstream Repository Basic Authentication

[abhisek]

Problem

The security gateway can be used to serve packages from private repositories. To support this, gateway must be able to support authenticating with the upstream repository.

Proposed Solution

Implement a basic authentication for upstream repository since almost all package managers or private repositories use this scheme of authentication. We can implement this in Tap Service:

• Prepare basic auth header based on configured authenticator
• Apply basic auth header in the request