What is the proper way to configure systemd-journald on NixOS? There seems to be no relevant configuration options. On Ubuntu, for example, I could edit /etc/systemd/journald.conf.

Context: I have recently discovered that by default systemd-journald can use gigabytes of disk space for its journal, unless limited by SystemMaxUse configuration option.

2 Answers 2


The file /etc/systemd/journald.conf is produced by the NixOS systemd module.

There are configuration options for journald, but not one specifically for SystemMaxUse. What you can do is use the services.journald.extraConfig option to append whatever else you need to journald.conf.


This should be the option when there is no other extraConfig

services.journald.extraConfig = "SystemMaxUse=100M";

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