oauth2_proxy + nginx auth_requstのサンプルだよ

oauth2_proxy.conf

# please include in server context
# ref: https://github.com/bitly/oauth2_proxy#endpoint-documentation

# for checking login status.
# only returns a 202 Accepted response or a 401 Unauthorized response;
location = /oauth2/auth {
  internal;

  # return 202 if local request, for inftataster test
  set $local 0;
  if ($remote_addr =  "127.0.0.1")  { set $local 1; }
  if ($remote_addr ~* "^172\.17\.") { set $local 1; }
  if ($remote_addr ~* "^192\.168")  { set $local 1; }
  if ($local = 1) { return 202; }

  proxy_pass http://127.0.0.1:4190;
  proxy_set_header Host $host;
  proxy_pass_request_body off;
  proxy_set_header Content-Length "";
}

# to start oauth cycle
location = /oauth2/start {
  internal;
  proxy_pass http://127.0.0.1:4190;
  proxy_set_header Host $host;
  proxy_pass_request_body off;
  proxy_set_header Content-Length "";
}

# to complete oauth cycle
location = /oauth2/callback {
  auth_request off;
  proxy_pass http://127.0.0.1:4190;
  proxy_set_header Host $host;
}

great document 💯