Still struggling with a container deployment, this time with bind mounts and file ownership.
What I want: Mount a file into a container and have it be owned by a specific user
I found this relevant issue: https://github.com/NixOS/nixpkgs/issues/329530

I'm trying to follow a workaround that was posted there:

bindMounts.localConfig = {
  mountPoint = "/run/canteendle/config.local.edn:idmap";
  hostPath = "/run/agenix.d/canteendle/config.local.edn";
  isReadOnly = true;
};

The file in question on the host is owned by canteendle:canteendle.

Starting this container fails with the following error:
Failed to map ids for bind mount /tmp/nspawn-root-TVO12v/run/canteendle/config.local.edn: Invalid argument

I'm wondering why idmap doesn't work