Since I’m trying to use org-agenda more, I spent a bit of time setting it up to show my CalDAV calendars (usually work meetings) using vdirsyncer, khal, khalel and nix/home-manager. I didn’t find any HOWTO on the web, so I had to read the documentation of the tools (yes, I know, the horror :D) to set it up, hence this write-up.
Let’s start with home-manager to install and configure vdirsyncer (which sync CalDAV calendars locally) and khal (which is an interface for the local calendars).
This has been resolved on GnuPG version 2.4.4, it still is interesting to see how nix could help find an easy workaround to this issue.
Some time ago, I upgraded Emacs to version 29.1 which has some issues with GnuPG >= 2.4.1. At first, I simply fell back to GnuPG 2.2.x using pkgs.gnupg22 in my Nix configuration but since it is insecure, Nix refused to build without me setting the NIXPKGS_ALLOW_INSECURE environment variable to 1.