Long story short: the SSH agent protocol doesn't support telling from
which tty the request is coming from, so the the pinentry curses prompt
appears on the login tty and messes up the output and may hang.
The current trick to workaround this is informing the gnupg agent every
time you start a shell: this assumes you will run `ssh` in the latest
tty, if you don't the latest tty will be messed up this time.
The ideal solution would be updating the tty exactly when (and where)
you run `ssh`. This is actually possible using a catch-all Match block
in ssh_config and using the `exec` feature that hooks a command to the
current shell.
Source for the new trick: https://unix.stackexchange.com/a/499133/110465
the conversion procedure is simple:
- find all things that look like options, ie calls to either `mkOption`
or `lib.mkOption` that take an attrset. remember the attrset as the
option
- for all options, find a `description` attribute who's value is not a
call to `mdDoc` or `lib.mdDoc`
- textually convert the entire value of the attribute to MD with a few
simple regexes (the set from mdize-module.sh)
- if the change produced a change in the manual output, discard
- if the change kept the manual unchanged, add some text to the
description to make sure we've actually found an option. if the
manual changes this time, keep the converted description
this procedure converts 80% of nixos options to markdown. around 2000
options remain to be inspected, but most of those fail the "does not
change the manual output check": currently the MD conversion process
does not faithfully convert docbook tags like <code> and <package>, so
any option using such tags will not be converted at all.
most modules can be evaluated for their documentation in a very
restricted environment that doesn't include all of nixpkgs. this
evaluation can then be cached and reused for subsequent builds, merging
only documentation that has changed into the cached set. since nixos
ships with a large number of modules of which only a few are used in any
given config this can save evaluation a huge percentage of nixos
options available in any given config.
in tests of this caching, despite having to copy most of nixos/, saves
about 80% of the time needed to build the system manual, or about two
second on the machine used for testing. build time for a full system
config shrank from 9.4s to 7.4s, while turning documentation off
entirely shortened the build to 7.1s.
some options have default that are best described in prose, such as
defaults that depend on the system stateVersion, defaults that are
derivations specific to the surrounding context, or those where the
expression is much longer and harder to understand than a simple text
snippet.
This adds yubikey-agent as a package and a nixos module.
On macOS, we use `wrapProgram` to set pinentry_mac as default in PATH;
on Linux we rely on the user to set their preferred pinentry in PATH.
In particular, we use a systemd override to prefix PATH to select a
chosen pinentry program if specified.
On Linux, we need libnotify to provide the notify-send utility for
desktop notifications (such as "Waiting for Yubikey touch...").
This might work on other flavors of unix, but I haven't tested.
We reuse the programs.gnupg.agent.pinentryFlavor option for
yubikey-agent, but in doing so I hit a problem: pinentryFlavour's
default value is specified in a mkDefault, but only conditionally. We
ought to be able to pick up the pinentryFlavour whether or not gpg-agent
is running. As a result, this commit moves the default value to the
definition of programs.gnupg.agent.enable.
This solves the dependency cycle in gcr alternatively so there won't be
two gnupg store paths in a standard NixOS system which has udisks2 enabled
by default.
NixOS users are expected to use the gpg-agent user service to pull in the
appropriate pinentry flavour or install it on their systemPackages and set
it in their local gnupg agent config instead.
Co-authored-by: Florian Klink <flokli@flokli.de>
