Nginx never sends the body with the auth_request sub-request, but
keeps the original Content-Length header by default. Without some
config tweaks, this results in the request to /oauth2/auth hanging.
/oauth2/auth is not more sensitive than other /oauth2/ paths,
does not need "internal" protection
"spdy" protocol is obsolete, http2 is the thing to enable now.
But it's orthogonal anyway.
No need for two separate content/upstream location blocks in
this example, reduce to just one, with a comment that it could
be serving files instead of proxying.
golang.org/x/oauth2/google is same repo as golang.org/x/oauth2
- this sometimes confused gpm/git
cloud.google.com/go/compute/metadata is a missing dependency
of golang.org/x/oauth2