epub manuals are holding back the transition away from docbook, and
cursory research does not suggest that they are used very much. it's
still very early in the 23.11 release cycle, so if we're going to find
out just how many people do use the epub manuals it should be now.
this need not be the end of epub manuals. nixos-render-docs could be
extended to also export epubs, but that has not been done yet since it's
going to be some effort with unknown real-world usefulness.
The nixos/caddy module is somewhat old by now
and has undergone quite some refactors.
This specific module option (originally named
`ca`) used to make a bit more sense when
Caddy did not have multiple ACME CAs as
fallback (LE & ZeroSSL) by configured by
default yet (ZeroSSL came with v2.3.0).
I also rephrased the description slightly,
to mention Caddy's automatic issuer fallback
and a note which this option maps to in the
Caddyfile, to provide a bit more context and
a more up-to-date recommendation.
Specifically that "fine-grained configuration"
section comes from a time when this module did
some custom tls/issuer config json merging
with the templated Caddyfile using `jq`.
The "The URL to the ACME CA's directory"
section is a word-for-word copy from the
official Caddy docs, which also include a link
to LE's docs to the referenced staging
endpoint. So I added that as well.
PROXY protocol is a convenient way to carry information about the
originating address/port of a TCP connection across multiple layers of
proxies/NAT, etc.
Currently, it is possible to make use of it in NGINX's NixOS module, but
is painful when we want to enable it "globally".
Technically, this is achieved by reworking the defaultListen options and
the objective is to have a coherent way to specify default listeners in
the current API design.
See `mkDefaultListenVhost` and `defaultListen` for the details.
It adds a safeguard against running a NGINX with no HTTP listeners (e.g.
only PROXY listeners) while asking for ACME certificates over HTTP-01.
An interesting usecase of PROXY protocol is to enable seamless IPv4 to
IPv6 proxy with origin IPv4 address for IPv6-only NGINX servers, it is
demonstrated how to achieve this in the tests, using sniproxy.
Finally, the tests covers:
- NGINX `defaultListen` mechanisms are not broken by these changes;
- NGINX PROXY protocol listeners are working in a final usecase
(sniproxy);
- uses snakeoil TLS certs from ACME setup with wildcard certificates;
In the future, it is desirable to spoof-attack NGINX in this scenario to
ascertain that `set_real_ip_from` and all the layers are working as
intended and preventing any user from setting their origin IP address to
any arbitrary, opening up the NixOS module to bad™ vulnerabilities.
For now, it is quite hard to achieve while being minimalistic about the
tests dependencies.
