Taskserver fails to start on NixOS - nixos

Question

I have a NixOS 17.03 server with the taskserver package. The taskserver service do not start anymore (it used to start, but I can't track the precise moment when it stopped working).
Here is the portion of my configuration.nix related to taskserver :
services.taskserver.enable = true;
services.taskserver.fqdn = config.networking.hostName;
services.taskserver.listenHost = config.networking.hostName;
services.taskserver.organisations.myorga.users = [ "henri" ];
Ande the error details :
systemctl status taskserver
● taskserver.service - Taskwarrior Server
Loaded: loaded (/nix/store/dy9rz3al85s6rxifrwqmm6sf3nsnb6wz-unit-taskserver.service/taskserver.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Sat 2017-05-27 19:52:27 CEST; 15min ago
Process: 5241 ExecStart=taskd server --ca.cert=/var/lib/taskserver/keys/ca.cert --ciphers= --client.allow= --client.deny= --confirmation=true --daemon=false --debug=false --extensions= --ip.log=false --log=- --queue.size=10 --request.limit=1048576 --server.cert=/var/lib/taskserver/keys/server.cert --server.crl=/var/lib/taskserver/keys/server.crl --server.key=/var/lib/taskserver/keys/server.key --server=myserver:53589 --trust=strict (code=exited, status=255)
Process: 5239 ExecStartPre=/nix/store/29h8k2nld3cwmvqiqml125jxm7ndl62j-unit-script/bin/taskserver-pre-start (code=exited, status=0/SUCCESS)
Main PID: 5241 (code=exited, status=255)
May 27 19:52:27 myserver systemd[1]: taskserver.service: Main process exited, code=exited, status=255/n/a
May 27 19:52:27 myserver systemd[1]: taskserver.service: Unit entered failed state.
May 27 19:52:27 myserver systemd[1]: taskserver.service: Failed with result 'exit-code'.
May 27 19:52:27 myserver systemd[1]: taskserver.service: Service hold-off time over, scheduling restart.
May 27 19:52:27 myserver systemd[1]: Stopped Taskwarrior Server.
May 27 19:52:27 myserver systemd[1]: taskserver.service: Start request repeated too quickly.
May 27 19:52:27 myserver systemd[1]: Failed to start Taskwarrior Server.
May 27 19:52:27 myserver systemd[1]: taskserver.service: Unit entered failed state.
May 27 19:52:27 myserver systemd[1]: taskserver.service: Failed with result 'exit-code'.
journalctl :
May 27 19:52:27 myserver systemd[1]: Starting Initialize CA for TaskServer...
May 27 19:52:27 myserver systemd[1]: Started Initialize CA for TaskServer.
May 27 19:52:27 myserver systemd[1]: Starting Taskwarrior Server...
May 27 19:52:27 myserver systemd[1]: Started Taskwarrior Server.
May 27 19:52:27 myserver taskd[5241]: ERROR: Could not read include file '/nix/store/8g6zs5xf1yvbkv8nzjgjqc3zgwjfy8a8-taskdrc'.
May 27 19:52:27 myserver systemd[1]: taskserver.service: Main process exited, code=exited, status=255/n/a
May 27 19:52:27 myserver systemd[1]: taskserver.service: Unit entered failed state.
May 27 19:52:27 myserver systemd[1]: taskserver.service: Failed with result 'exit-code'.
May 27 19:52:27 myserver systemd[1]: taskserver.service: Service hold-off time over, scheduling restart.
May 27 19:52:27 myserver systemd[1]: Stopped Taskwarrior Server.
May 27 19:52:27 myserver systemd[1]: taskserver-ca.service: Start request repeated too quickly.
May 27 19:52:27 myserver systemd[1]: Failed to start Initialize CA for TaskServer.
May 27 19:52:27 myserver systemd[1]: taskserver-ca.service: Unit entered failed state.
May 27 19:52:27 myserver systemd[1]: taskserver-ca.service: Failed with result 'start-limit-hit'.
May 27 19:52:27 myserver systemd[1]: taskserver.service: Start request repeated too quickly.
May 27 19:52:27 myserver systemd[1]: Failed to start Taskwarrior Server.
May 27 19:52:27 myserver systemd[1]: taskserver.service: Unit entered failed state.
May 27 19:52:27 myserver systemd[1]: taskserver.service: Failed with result 'exit-code'.
The /nix/store/8g6zs5xf1yvbkv8nzjgjqc3zgwjfy8a8-taskdrc does not exists indeed. I tried to clean the store, to update and rebuild the packages, and even to upgrade to nixos-unstable, to no avail.
Technical details
System: NixOS 17.03.1203.58e227052d (Gorilla)
Nix version: 1.11.8
Nixpkgs version: 17.03.1203.58e227052d
Sandboxing enabled: false

Answer 1

The latest 17.03 branch has no references to taskdrc, because that file was removed.
But, reading that commit we can see, that reference to taskdrc file is written to ${cfg.dataDir}/config file. So, most likely, you should remove that include /nix/store/...-tasdrc line from your config for service to start.
The reason, why you have experienced such a breakage is that Hydra (NixOS CI) doesn't assume currently, that NixOS is sometimes upgraded and such migrations should be tested too.