Make the proxy redirect to an upstream download protocol (i.e. Olympus) with HTTP 301s

[arschles]

We voted in #423 (comment) to make the proxy issue HTTP 301 redirects to the CLI when the proxy datastore doesn't have the given module@version.

Note that we're going to do this for our first released version. We can add local caching/storage after that.

[arschles]

Also, this means that if you make the proxy "exclude" all modules in its exclude list, then it will act as if there is no upstream, fetch everything from the VCS (using go get on the backend), and store it all in its datastore.

[marwan-at-work]

@arschles did you mean "include" all modules? "excluding" all modules would return status forbidden.

[michalpristas]

exclude should break the communication.
Include goes upstream (whatever it is, for proxy its olympus, for olympus it's VCS)
direct goes to VCS without caring about upstream

[fedepaol]

Can I take this one?

[michalpristas]

This was discussed as post-MVP but sure @fedepaol

[michalpristas]

@marwan-at-work you self-assigned this few days ago, are you ok with @fedepaol working on this?

[marwan-at-work]

This is already done through the filter middleware and the global switch. Will close the issue and open a new one for cache filling.