This conforms to the NGINX subrequest result authentication protocol[1]
using the NGINX module `ngx_http_auth_request_module`. This is based on
the example that @peterkeen provided on Twitter[2], but with several
changes to make things more tightly locked down:
* This listens over a UNIX socket instead of a TCP socket to prevent
leakage to the network
* This uses systemd socket activation so that systemd owns the socket
and can then lock down the service to the bare minimum required to do
its job without having to worry about dropping permissions
* This provides additional information in HTTP response headers that can
be useful for integrating with various services
* This has a script to automagically create debian and redhat packages
for easier distribution
This will be written about on the Tailscale blog. There is more
information in README.md.
[1]: https://docs.nginx.com/nginx/admin-guide/security-controls/configuring-subrequest-authentication/
[2]: https://github.com/peterkeen/tailscale/blob/main/cmd/nginx-auth-proxy/nginx-auth-proxy.go
Signed-off-by: Xe Iaso <xe@tailscale.com>
