How do I increase the limit on the number of open files in NixOS?

Question

I'm testing out IPFS on NixOS and I'm seeing errors due to "too many open files" in the journalctl -u ipfs logs. ulimit -n shows the limit on the number of open files is set at 1024. How do I increase the file descriptor limit in configuration.nix?

Answer 1

I was able to increase the number of open files by adding the following to configuration.nix.

  security.pam.loginLimits = [{
    domain = "*";
    type = "soft";
    item = "nofile";
    value = "8192";
  }];

After running nixos-rebuild switch and reboot, ulimit -n reported 8192.

More specifically, it's also possible to limit the number of file handles used by the IPFS service by adding the following to configuration.nix.

services.ipfs.serviceFdlimit = 32768;